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TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 427 SBC Questions Reply to this post

I'm trying to build a 427 SBC in the coming months. I have a virgin 2-bolt block 400 block that I'm going to stroke. I'm looking at the following rotating kit-- http://www.theengineshop.com/sbkits3.shtml

I'm planning on just using ARP studs on the mains, and not splaying it. I really don't have the cash for that. I wanted to know if I needed to partially fill the block (to the bottom of freeze plugs) for clearancing. I was thinking this would make sure I don't hit the water jackets. This should keep the block really strong, and I think I will still be able to cool the motor off, as long as I don't fill too much.

What do you guys think of this so far? I'm hoping to order the rotating kit in the next couple of weeks (waiting on graduation money).

I plan on using my existing heads, but I might pockt port them first. I will also be using a big solid roller cam. The bottom end shold be up for 7,000RPM shifts right?

Any input is appreciated.
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

74vetteman
Senior Member


303 posts [100%]
Calgary

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

How much horsepower do you plan to make? I don't think you will need to spin that high of rpm. Even with a studded two bolt, I wouldn't go over 6500 rpm.

Before you spend any money on machining your block you should have the cylinder walls sonic checked to see how much iron you have (considering that you will need a 0.030" overbore). I would also have the block cleaned using the oven and shot peen method which also stress relieves the block as well as making it look like new. Then have it crack checked.

There are a few things that you should do prior to having the block machined. Port the oil passages in the rear main cap (get rid of sharp corners, chamfer oil ports, etc.), where the oil enters the block, and the filter mounting passages. Use a carbide burr on a high speed die grinder.

Fill the block to the bottom of the front side frost plugs (by the motor mounts). Before you start, install and torque the main bearing caps.It is fairly difficult to fill the block evenly. Use a slightly runny mixture and tap the block to help the fill settle. Start at the lifter side holes by the distributor and work your way to the front. make yourself a depth gauge so that you know when the fill is high enough. When you are finished filling one side, install and torque a head on. This, and torqing the mains, will re-create the stresses normally seen in the block, and is worth a few horsepower. Let dry over night and do the other side.

There are three large cooling holes on the lifter side of the deck (each side)that should be tapped for maximum deck strength. Use a 3/4 npt tap and use a solid pipe plug to thread into the hole. When your deck is machined flat ("decked"),use your head gasket for a template and drill the required cooling holes into the pipe plug (3/16" drill).

Use your die grinder to enlarge the oil drain back holes at the back of the block to get rid of the casting flash, etc. You can also smooth the valley walls where the oil drains out of the heads.

Since you are going solid roller, you may consider oil restrictors to meter the supply to the valvetrain. You may also want to plug the round valley holes that allow oil to splash on the cam (1/4" npt plugs).

Make sure you drill steam holes in your heads. You don't need a whole lot of cam to make big hp. I made the hp and torque in my sig with a mild hydraulic roller (222in and 230 exhaust @0.050"). Nothing worse than a over cammed engine on the street (IMO). I use a Edelbrock Victor water pump to keep it cool.

Good luck!!
_______

74 4-speed 406ci. 494lb/ft, 476 hp.

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

As 74vetteman asked, what is your power goal?

You mention 7000rpm shift point, if that was the optimum shift point , then you would need a relatively large cam and heads. My NA SBC 427 made a peak of 650hp at 6800 rpm, so my optimum shift point would probably be in the low 7000's. To get that from a 427, I used a 256/264 mech roller cam and my 18* heads have 255cc intake ports. My adivice for building these big strokers it to think of them in terms of small big blocks, because that's basically what they are, only you're handicapped by cylinder heads. Even with 18* heads that flow 355 cfm, I feel my engine was held back by cylidner head flow.

As you guys have already mentioned, filling th eblock to just below the freeze plugs is as good idea. It won't hurt your cooling since there's quite a difference in cylinder and block temperature at the bottom of the bore versus the top and combustion chamber.

A 17 year old with a 600hp SBC 427 Vette...I can only imagine the possibilities .


_______

1982 Coupe
Twin Turbo SBC 427

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (Monty) Reply to this post

I would love to reach close to 600hp, but I don't think it's going to be possible with my heads. I just don't have the cash to get them fully ported. I plan on running a cam with lift up in the mid-to high .600's. It will definately be a custom grind.

People always say cams this big aren't streetable, but I run about .540 lift (1.6 rockers) in a 350 with only a cheap 3000 stall. My car will idle at 850RPM in neutral. I am hoping to get an ATI 8 inch treemaster stall.

I think it will be a high 10 or low 11 second street car.

All of your help is definately appreciated.
Jay

PS--Monty, do you still have your headers, I can get adapter plates to use the on my heads. I would of emailed you, but I'm at school right now.
Thanks,
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

What heads do you have? Do you have flow bench numbers for them? A 300cfm head has the potential to make 600hp.

Lift really doesn't ahve much to do with whether a cam is "streetable" or not, it's more a matter of duration and overlap. If it were possible to run .700" lift with a 220 duration lobe, it would be totally streetable, idle well, and pull decent vacuum. The only problem would be the valve springs necessary to accomodate that lift would also typically be very stiff. Lift should be matched more to the flow characteristics of the cylinder head.

I don't have my NA headers in my possession, but I can possibly get them back. I gave/sold them back to the guy who built them for me and he was going to sell them to another customer of his. As far as I know, the guy never really got his project going, so he may not be using the headers afterall. I'll find out for you.

Jay, just keep in mind that what was appropriate for your 350 engine is going to be restrictive or too small for a 427. Don't be afraid to run a cam with 240+ degrees of duration at .050". I went through several cams on the dyno, and each time I swapped in a larger cam, I picked up horspower and torque all the way across the rpm range. The largest cam I tried actuall made more low rpm torque than the smaller one. We never did get to the point where we were sacrificing low/mid-range torque for high rpm power. As I mentioned earlier, I ended up sticking with a 256/264 duration cam, but I feel like I could have gone to 260/268 or so before I saw a loss of low end torque. Of course every application is different, and is dependent on many things such as static compression ratio and cylinder head flow, but it's still an indicator of how the extra cubic inches require more cam and head.


_______

1982 Coupe
Twin Turbo SBC 427

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (Monty) Reply to this post

I'm planning on using the heads that are on my 350 now. They are Dart Pro 215cc 64cc chambers with 2.05/1.60 valves. The runners have been polished, but no real porting. They should flow about 265 @ 0.50in lift.

I'm not scared of a little duration either. I currently have 240/246 duration, and it isn't bad at all.

Please keep me informed on those headers Monty.
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

I'd guess you're probably looking at around 500hp @ 5500rpm and 540 tq @ 4500rpm, with those heads, a 240/246 cam and 10.5 compression ratio, along with headers and your current carb and intake.
_______

1982 Coupe
Twin Turbo SBC 427

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (Monty) Reply to this post

You don't think the 427 could hold more duration? I was also thinking of switching intakes, and definately a bigger carb. I would love to get more horsepower, but I know it takes better heads. I'll have to try and get some work done to my current heads. Now, where to find the $$$................
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

A 427 could definitely use more duration, I was just offering you a guess on what I thought it would make based on the components you listed in your profile and the cylinder eheads you have. However, I would n't get too wild with the cam without working the heads first. In my opinion, always start with the cylinder heads, as the saying goes "cylinder heads make power." A set of good heads with a small cam will make more power and offer better drivability than a set of mediocre heads with a killer cam.
_______

1982 Coupe
Twin Turbo SBC 427

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (Monty) Reply to this post

Ok, I understand now.

What intake should use? I know my intake is pretty decent, but is it good enough?

I wanted to thank you Monty for all of your help so far, I've followed your engine build-up from the beginning. It's always real nice to see a guy with a killer motor THAT ACTUALLY DOES IT HIMSELF!

Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

MoMo
Moderator
Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

Jeeze. That's a lot of motor for a street car.
I agree that the heads will hold you back. What I might suggest if you really want mid-600 hp numbers is to stick a roller cam in it with a strong midrange, fuel inject it, and then put a blower on it. Probably a good intercooled centrifugal supercharger, or maybe a screw-type supercharger.
Then you will definitely have a streetable engine that'll make the serious power numbers for dragrace time at the strip.

If you go monster huge on the cam and build the engine for a shift point of 7000 rpm, think about the massive amount of stall you'll need to be able to launch at or close to your torque peak. I have run a 3800 stall on a big block Firebird for a few years now and that's about as large as I'd want on the street. If you end up needing a 4500 or 5000 stall, you can kiss streetability goodbye. Especially with an enormous cam. Partial throttle would be hell in that thing.
Anyway, that's just my opinion.

If you do keep it naturally aspirated and 500 to 550 hp and tq is not enough, then another option is to get a nitrous system. That'll get you the power numbers you're after too, despite small block Chevy head flow limitations. That way, you can "put away" that last 150 hp until you need it at the track, and when you have race gas in the tank, and at all other times, you have a very torquey, very streetable engine.

But I agree that you just will not need 7000 rpm on such a torquey street motor. Besides that, I wouldn't spin those kind of rpm's on a two-bolt main. Especially not without the very best and longest forged H-beam connecting rods and forged crank and 4-bolt splayed mains.
You'll find like I did, that building up a trick 400-based stroker is far more expensive than an equally powerful big block that will always breathe better.

My suggestion is to lower your operating rpm band a bit, and get that extra power with nitrous or a blower maybe. And if carbed, the Edelbrock Performer RPM Air Gap is about the best intake I've ever seen.

IMHO...
_______

1968 Corvette Roadster
Receiving 630 hp 427 upgrade!
Muncie w/Hurst pkg, 3.36 posi (so far)
Bronze/Dark Orange w/white top

1968 Pontiac Firebird
505 hp/522 lb-ft 465
TH400, 3800 rpm stall, 3.08 gears (soon to be 4.10 9-inch)
Purple/Black interior

Daily Drivers:
86 Shelby Charger, 86 IROC-Z Camaro

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

The kit includes top of the line Eagle H-beams and forged crank. It should be good for whatever I throw at it within reason.

What do you think about the rings being so high? I know it would be able to hold a little Nitrous, but how much is the question. I am not building this motor for Nitrous, but I might (big might) use it later.

My friends spray everything, but I prefer to keep it all motor.
Jay

autoxer
Senior Member


1245 posts [100%]
St. Petersburg FL

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

I'm basically building the same motor, I'm looking at about 550-560 HP. I'm gonna use the Dart Pro 230cc's with 2.08 and 1.65's, those valves will also fit in your head for a little bit more flow. I'm going to use the Comp cams 12-443-8 (242-248 .540-.562) with 1.6's for .576-.599 and have them grind it with a small base circle and 112 lobe separation. This should be a very streetable and torquey cam up to about 6500,,not gonna go too much above that with the 400 2 bolt. For an intake I'm using the new demon Mighty Mouse 825 CFM with an air gap RPM intake, American Speed builds some great high HP 400 SBC's with this intake and they said on the dyno up to about 6500 it only gives up 7HP to the Victor Jr. with a lot better torque numbers down below, and since I'm running an auto, I feel the dual plane will give me better streetabilty. So that's my recipe,,basically everything's the same except I'm not filling the block, it's already been decked, line bored, lifter valleys done, bead blasted, baked oil restrictors and everything else you can do to a 400 after sonic testing good. I plan on giving this motor a 200 shot with a plate system. So I'll be watching your build to see how everything goes. I'm about 2 months away from completion of the motor (too many other things on agenda).
_______

Autoxer (NCCC)
88 Auto Coupe

MoMo
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Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (autoxer) Reply to this post

You two guys, please use 6-inch rods. Even with that, the rod/stroke ratio of the 427 SB won't be too good. But it will help. The high pin location of the pistons if anything will help control piston rock and increase stability. There isn't much room for rings, that's true. But you'll be okay. This won't be a real eager revver, as compared to a 350 for example. So I'm not too sure about building it for a power peak so high that you'll be pushing some dangerous piston speeds to reach it. Even with modern metallurgy, 6500 rpm will be pushing it on those motors. I'd be very concerned about someday having a rod exit the block or getting sideways in the bore.
I know more and more engine builders are less and less concerned about piston speeds and rod/stroke ratios than in the old days. This is no doubt because of some very good metallurgical advances in recent years.

In otherwords, it'll work great and make buttloads of power and torque, but if there's one little flaw or hairline crack, BOOM...no warning.
Maybe I'm a little old fashioned, but that worries me about these monster big blocks.

One thing's for sure though, you'll run with big blocks and handle like small blocks. Just watch those stratospheric rpm's on these giant SBC strokers.

MoMo
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Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (MoMo) Reply to this post

One more comment. Call me nuts, but what I plan to do with my 400 SBC that I decided not to stroke is to DESTROKE it. That's right. Forged 350 crank and 6-inch forged H-beam rods. That gives a rod/stroke ratio of 1.724. Very close to the famous rpm-happy 327's. Except 50 more cubic inches at 377. Then cam it with a modern solid roller cam, set it up for low compression with some dished pistons, and twin turbocharge and intercool it.

That'll probably make some similar power numbers that you guys will be at, except by going the opposite way with the stroke and using turbos. It'll be softer on the bottom end, but no worse than your average street 350 with a healthy build up. However, in the midrange, things start getting interesting real quick. You'll hear a pair of turbos whistle as they "come on line" and then BAMMMMM!!!! Just like a freight train ramming you in the back.

I know how I'm going to build it up, just not exactly what I'm going to put it in. I'd love to find a 68-73 Corvette coupe to put it in, because of the great bod and plenty of room for turbos and a huge intercooler. That with a ZF-6 speed or ROD and some nice steep rear end gears, (3.90 would be good), would make that an interesting project.

And I'm sure except for the off-line response, it'll about run with my 427 Corvette, which will probably have the same power numbers.

There's more than one way to skin a cat. (Or a Viper).

HunterRose
Senior Member




92 posts [100%]
SouthWest MI

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 Re: 427 SBC Questions (MoMo) Reply to this post

This is a great thread, since I'm still running numbers to see how I want to build up my rocket block!

Momo, I thought about doing exactly that, destroking, but I'm not convinced that I'd really be taking advantage of the higher RPM potential by doing that.

Out of curiosity, what are the limitations on rod length? Monty's running 6.125's, which is pretty long, but a tall deck looks like it might even handle a BB rod at 6.325, or would that be cutting it too close?

Tony
_______

1976 L-48 Dark Green ---> Rocket Block project underway!

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (HunterRose) Reply to this post

Tony,

Your only limit to rod length is space. If you have a 9.325" deck height, with a 4.00" crank, that means you have 7.325" to fit in your rod, the piston compression height, and a deck distance if any (the distance between the piston top and the plane of the blcoks deck surface).

Deck height = 1/2 (stroke) + rod length + piston compression height + deck distance (if any)

We milled my Dart Iron Eagle/Rocket block deck down to 9.300 to standardize and square it. With a 4.00 stroke and 6.125" rods, I run pistons with a 1.175" compression height with leaves the piston .010" in the hole. With .029" gaskets, that gives me a .039" quench height which is in the optimum range. A longer rod would really pack the rings together, practically eliminating the possibility of N20 or forced induction since the top ring should be at least .300" down. You might be able to run a 6.200" rod, but I think that would be the longest with a 4.00 stroke and the 9.325" deck height. The aluminum Dart/Rocket blocks with a 9.500" deck would certainly allow a longer rod though.

With a 4.00" stroke and 6.125" rods, you end up with a 1.53 rod/stroke ratio whcih is identical to a 454 big block, and slightly better than the 1.52 rod/stroke ratio a 5.7" rod 383 has. We spun my SBC 427 up to 7500 rpm on the dyno during testin/tuning without worry. The Crower billet rods are rated to 8500+ rpm, so I never felt unfomfortable, and the engine accerlates very quickly, the guys at Fast Times commented on how "frisky" it was.

There seems to be many differing opinions on whether rod length and rod/stroke ratio is really that importnat. I've read articles and comments from many well-known engine builder snad it seems about half of them recoomend running the longest rod possible, while the other half consider the rod nothing more than just a means of connecting the piston to the crank. I tend to think that you should always strive for the best rod/stroke ratio possible, within reason, and keep it above 1.5. However, I wouldn't sacrifice displacement by running a shorter stroke just to get a better rod/stroke ratio. I just build street engines that don't see 8000+ rpms for extended periods of time. If I were building a road racing engine that would be spun that high for extedned periods of time, I'd defintely destroke it, run longer rods, as well as use small main and rod journal (Honda size) diameter to reduce bearing speed.

[Modified by Monty, 11:03 AM 5/7/2002]
_______

1982 Coupe
Twin Turbo SBC 427

MoMo
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2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (HunterRose) Reply to this post

Rod length is limited by compression height. That gets pretty tricky. But if you work with your machinist or a knowledgeable parts source rep, you can usually increase rod length by altering the piston design. You can get custom pistons too, but of course, price increases the more exotic you go.

A 6 inch rod can be put in about any small block Chevy and still use off the shelf pistons that are widely available. For over 6 inch lengths, you really need to work with someone who can calculate that and advise you. I've worked with PAW and Speedomotive in the past, as well as a decent machinist. But I find machinists tend to be impatient and less willing to help because you're taking time away from their machine work that they have stacked up. Call Speedomotive at (562)945-2758 and ask them. Tell them you want to get the longest rod possible and still use available pistons without having to go custom, and see what they can do for you.

Keep in mind that the higher the pin location and the smaller the compression height, the higher the resulting compression. You'll have to tell them your desired compression ratio, and the pistons will have an increasingly deep dish to compensate. In otherwords, you couldn't very easily build a stroker AND keep compression low enough to use forced induction. By building a stroker, you're pretty much dedicating yourself to naturally aspirated use.

I thought of destroking because then it's a lot easier to get a killer rod/stroke ratio and longer rods and still be able to easily lower compression with available pistons and heads. Then if I wanted to run it fuel injected and naturally aspirated for awhile, I could use a steel shim head gasket and still have 9.5:1 compression with a 72 cc combustion chamber. Then use a Felpro thick head gasket to drop it to 8.5 later and convert to forced induction. The only complication would be a cam change to run a supercharged or turbocharged cam grind.

A 377 with 9.5:1 compression with an LT1 or Miniram FI set up and full dual exhaust would still be no slouch as a street engine. The only thing I was worried about is, to run the kind of cam duration it would take to make full use of a 377's rpm potential, I'd have trouble passing emissions. So that's why I'd use it on a pre-'74 car.
I'd expect to make around 350 to 400 hp at the rear wheels with a high-revving, solid-roller 377, and probably pick up another 200 hp by twin turbocharging.

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (MoMo) Reply to this post

Momo,

Only 200 more hp from twin turbocharging? Yeah right . You'll get used to that real quick and you'll be turning the wick up in no time!
_______

1982 Coupe
Twin Turbo SBC 427

MoMo
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Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (MoMo) Reply to this post

Hi Monty! Long time no talk.
We must have been posting simultaneously.

The only comment on the rod/stroke ratio debate that I have is my own personal experience driving a 327 with a 1.73 rod/stroke ratio, and a 350 with a 1.64 rod/stroke ratio. They had a similar build up otherwise.

With the 327, the engine tended to climb in rpm's so much easier and more eagerly. It really was very noticeable. Plus with the shorter stroke, the piston speed is a lot less, and that's a fact. You really can go higher in rpm with identical rods as compared to an engine with a longer stroke, because the piston speed is a lot lower at a given rpm.

The 350 in comparison had much better torque, and still revved okay, but not as well as that 327.

Likewise, a 427 or 396 is going to rev noticeably better than a 454 or 502.
Some engine builders don't believe it, others do. I do because I've built both and compared them on the same car.

So that's part of the rationale for a destroked motor. The other part is the ability to more easily lower compression to used forced induction. As you say, a 4-inch stroke is not going to allow you to run forced induction with such a short compression height. I agree with you.
However, nitrous is another story. You can have high compression and still run nitrous. You have to have good high octane fuel in sufficient quantity and timing backed off to avoid detonation. But people do it all the time at the strip. Some people run a fuel cell and switch the fuel source over when they engage nitrous, which is an excellent idea.

By the way, your engine looks very nice.

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (MoMo) Reply to this post

It has been awhile. You must be real busy in "real life" cause I haven't seen you on the forum much lately, although if I had as many projects going on as it sounds like you do, I wouldn't be on the forum much either.

When I decided to turbocharge my SBC 427, there was some question as to whether I would be able to use my 6.125" rods(although I had a line on a brand new set of carillo titanium rods and wrist pins that were 6.100" long - they're still available if anyone wants them, $1600 brand new, plus $800 for the wrist pins) and still lower the Cr from 11.27 to 8.5 (my target CR). We were concerned that the 1.175" compression height would be too small and force the rings to be too close to the piston top, but JE managed to fit them all in and use a dish large enough to drop the CR down to 8.5. We even ended up witht he top ring .310" dwon, which is right where it needs to be. Of course I had to give up a bit of quench area for the dish, but there always seems to be a compromise.

Thanks for the compliment. I'm interested to hear about/see the 377 TT you're building/planning.

[Modified by Monty, 11:37 AM 5/7/2002]
_______

1982 Coupe
Twin Turbo SBC 427

MoMo
Moderator
Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (Monty) Reply to this post

Wow.

Members, Monty here is the person to see for all your small block stroker questions. I am very impressed with what you've been able to accomplish. I wouldn't have thought it was possible to lower compression enough in a 427 SBC to turbocharge.
Expensive...but NICE!!!

The 377 is not started yet. It is just planned.
I am busy with my 427 BBC conversion project right now. That's in the Shark.
In my 68 Firebird, I am busy getting the rusty cancerous panels off and getting it ready for a paint job, which I'm going to have to do myself.

I am on the forum, but much more in the background, kind of overseeing things more than commenting on posts. I'm more into the observer mode because of how busy I am.

Are you bringing your "Tiger Shark" to the Cruise In by any chance???

Monty
Senior Member




4399 posts [100%]
Park Ridge IL

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 Re: 427 SBC Questions (MoMo) Reply to this post

I was hoping to make the Cruise-in, but the guy who helped me with my headers, intercooler, and exhaust took 4 months to complete it, rather than the "3 to 4 weeks" he promised back in January . I'll probably be dyno testing/tuning that weekend. Next year I guess....

[Modified by Monty, 2:25 PM 5/7/2002]
_______

1982 Coupe
Twin Turbo SBC 427

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (Monty) Reply to this post

Thanks for all the help guys. I'm really excited about this engine build. Let the Graduation money come!!!

I'm going to try to get out to the track Friday. It just depends if I get back from fishing in time.

I've been running 12.6 with 235/60/15 Eagle tires, stock clutch fan, and 3.36 gears. I just went to 4.11s, elactric fans, and BFG drag radials. I'm really hoing for LOW 12s. What do you guys think?
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

thejaf
Senior Member




1813 posts [100%]
Roanoke Virginia

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 Re: 427 SBC Questions (MoMo) Reply to this post

This made for some interesting reading. I have a 406, that with the help of some forum members (Lars, Ruff71, mountainmotor, etc) is finally seeing the light of street use.

Let me ask you guys about timing for a second. I had SERIOUS detonation issues with my 406 when I bought it. ironing those issues out, I learned that timing these larger small blocks is not quite the same as the 350 or 327. That 36-38* is just too much, and that 32-34* is about perfect. Any input on that?

One of the mistakes made by whoever built my engine originally was putting ported and polished "041" 64cc heads on a 406 that had been zero decked with flat-top 2-releif pistons. That pushed comp ratio above 11:1, and there was no way I could run this on the street.

Now, the cam will be changed this summer. Currently it's a solid lifter, dual pattern long duration of unknown origin. From my measurements it's very similar but a hair more radical than the 1970 LT-1 cam. I have this car dialed in as best as I can currently, and it's still barely streetable. Cam gives me 8-10 inches Hg vacuum at idle, which is just barely enough to operate the lights and wiper door, because those systems are in 100% perfect working order. It is NOT enough to properly operate the power brakes. I had to buy a separate vacuum reservior, and even so, stopping when backing out of the driveway requires 2 feet.

The car currently has 3.73 rear end, with a TH-400. I'm also assuming it has a higher than normal torque converter, since I have some slippage, plus the cam would require it. This makes highway driving rather unpleasant to say the least. I'm spinning 3500 rpm just to keep up with traffic. Gets old after an hour or so.

Anyway, just keep in mind what type of driving you are going to do with your car. If you're ONLY taking this car to the track, have a good supply of 93+ gas (boosters don't do dick), then by all means go balls out. BUT....if you ever want to drive you car when you go out to eat, take trips in it, go to Carlisle, etc. i would seriously consider your engine package as a whole. This means a decent midrange cam, comp ratio under 9:1, mid-rangey rear end gears, etc. I'd rather have a 12-13 second car I could drive and enjoy than a 10 second car I could only do 1/4 mile runs in. Just depends on what you're after.
_______


1972 coupe with NOM 406 small block, Q-Jet, distributor, and heads by Lars. GM Mystery solid lifter cam, noisey but fun

My Homepage
My Music, Dang it!

clem zahrobsky
Cruise-In I Veteran
Cruise-In II Veteran




3550 posts [100%]
delmont pa

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

seem to me a waste of time and money to use a stock chevy 400 block to build a engine of this size and power. buy a HD block.
_______

a.k.a. MOTORMAN, 2002 torch red coupe, proud corvette owner since 1959
NCM member#5583
NCM ambassador from Corvette Club Of Western Pa
9TH-VETT vanity plate

HunterRose
Senior Member




92 posts [100%]
SouthWest MI

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 Re: 427 SBC Questions (Monty) Reply to this post

Thanks Monty & Momo for the excellent information!

Basically I'm going to stick with an NA setup for now, but may consider a centrifugal supercharger later on...

Just looking around and playing with numbers, theoretically if I can find 0.930 CH pistons (lowest stock ones I've seen is 1.000 CH), I could run a 6.385 rod.
That'd put the r/s ratio up to 1.600 and still have a good compression range for pump gas.

As for ring seal (which might be a problem with a piston like that), I should be pretty good since I have hopefully landed a good deal on a 5-stage pump which should generate some serious vacuum in the crankcase!

Tony

[Modified by HunterRose, 2:17 PM 5/7/2002]
_______

1976 L-48 Dark Green ---> Rocket Block project underway!

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (clem zahrobsky) Reply to this post

3.73-4.11 gears were the norm in the sixties. Most sportscars had them. That doesn't mean they didn't drive them, it just means they used more gas than everybody else.

I like having a motor that is on the verge of streetable. I drive my car all around (It's sitting in the school parking lot right now). It sure is nice to know that you can smoke just about anybody you'll see on the road.

I simply can't afford an aftermarket block, fuel injection, overdrive, and the like. But that doesn't mean I can't have a fast car. I just have to live with a less streetable car.

I wish I had the money to do an awesome build-up. But I don't. So I have to do it myself, and get suggestions from people that know what they're doing so I can get it right the first time.
Thanks,
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

MoMo
Moderator
Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

Well, a 12.6 on a 350 engine is very good performance. But if that's not quick enough, you may want to simply consider a 406 with 6-inch long rods. That'll give you the power to hit low-12's, possibly 11's, especially with the rear end you're running. Plus the 406 will be a very good street engine that won't need a huge cam to run those times. I doubt if you'd ever have to exceed 6500 rpm, so you could save yourself the trouble and go with a hydraulic roller cam. You won't even need to use a forged crank. You could go with a cast steel crank, or even an iron crank and be just fine. Go ahead and get good forged rods though, but I-beams would be sufficient.

Why a 406 instead of a 427 SB? Because it could be the difference between a $4000 build up and a $10,000 build up, and that's conservative. The 427 will make tons more power, sure. But if you want to play that hard, you gotta pay.

If you decide to spray nitrous on a 406, you'll definitely be buried very deep in the 11's. Plus you'll have an engine you can live with easily on the street. A 406 built right is a good motor. Might be something to think about.

3.73 and 4.11's were certainly available in the 60's, but they were not the norm. Transmissions of the day only had a 1:1 top gear, so rear ends tended to be 3.36 or numerically lower. In 1968, a 3.36 posi was the best rear end you could order. (Correct me if I'm wrong, but my research indicated that). You could get an aftermarket gear set, and racers did. But from the factory, I think 3.36 was the best you could do.

An option that a lot of people like to use is to keep their 3.08 or 3.36 gears the same, and get the extra low end gear using a Richmond 5 or 6 speed. That makes gears 1-4 the same as a Muncie with a performance rear end, but you still get the tall 1:1 or OD for the cruise.

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (MoMo) Reply to this post

The rotating kits that I have been pricing for a 406 would still run me $1200. The 427 is only $1800. Where sdoes all of the extra cost come in. I've never took on a project like this, so I may be forgetting about something. Even if I can't afford the best heads, My Dart Pro 1's should be decent.

I'm really hoping to hit 11's in my 355 before I put in the 427. I think I could hit 10s all motor eventually.

Thanks for all the help,
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

thejaf
Senior Member




1813 posts [100%]
Roanoke Virginia

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 Re: 427 SBC Questions (TeenagerWith74Vette) Reply to this post

not streetable (based on my not streetable 406) means that:

1. Idle is rough at best. put car in neutral at stop signs, lights, then BANG! back in gear. this gets old quick. of course, you can set the idle speed higher, but then you are banging into gears even harder when shifting, and you are also dieseling the car when you shut the engine off.

2. You have no lights or power brakes

3. You must buy race gas. which, when you can find it, is only allowed to be dispensed into 5 gallon containers, and not directly into the vehicle.

4. Say you actually fill up your gas tank, at 8 mpg with a 14 gallon tank, you can drive only about 50 miles from home before you have to turn around. unless you want to carry fuel containers in the storage compartment.

5. You have very poor cold starting

The whole advantage with using a 400+ CID small block is the displacement. Don't use similar 302/327/350 logic. Use big block logic. Get that torque curve starting low and going broad. Use what you have now (heads, gears, tranny converter) and contact somebody like Elgin or Schneider cams, and have them give you the #'s optimal for what you have.

When my 406 was 11.5:1, ported polished heads, single plane manifold, blah blah and all that crap, it was so horribly tuned down for street use that it was a DOG! No smoking tires, no pinned to the seat feeling. and I was getting 7 mpg I lowered compression to 9.7 by using stock 400 SBC heads, put on a Q-Jet, got my timing set up correctly, Edelbrock performer intake, and now it's one hell of a fun ride, at 14 mpg too!!! Now I have to be careful on dry roads. And this is with the current cam, which is not optimal, and the 2" dual exhaust. This summer I'm increasing exhaust to 2.5", installing a cam selected for me, and then I should have too much torque, thus I can go for a milder rear end gear.

I'm still learning, but trying not to repeat mistakes made by the previous owner of my car. keep in mind that old adage: "horsepower wins arguments, torque wins races"

MoMo
Moderator
Cruise-In III Veteran




2729 posts [100%]
Morrison CO

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 Re: 427 SBC Questions (thejaf) Reply to this post

Teen with 74, there is a lot of hidden cost. A good set of small block aluminum heads will pretty easily run you $1400. If you want to have any additional machine work to improve them further, add $500, or less-depending on what you do. Machine work on your block, should include align-honing the mains and honing the bores with a torque plate. Then you want it filled on the bottom, and machined for clearances. I think machining the block will cost you around $1500 give or take a few hundred. The intake manifold will cost a few hundred. The carb, if purchased new will cost $400 to $700, depending on what you get. The solid roller cam you propose to get is about an $1100 set up, including cam, roller lifters, roller rockers, and chrome-moly pushrods. Headers to flow what this beast will want to flow will run you $400 or so for a set of Hooker Supercomps. The rest of the exhaust, once optimized, could run you another grand, because no one makes a good enough aftermarket bolt-on exhaust system for a C3 Corvette. You'll need an electric fuel pump for a few hundred, and an upgraded radiator for around $500. New water pump for a hundred. A baffled oil pan with increased capacity is probably 2 or 3 hundred. You definitely need to upgrade all your U-joints at the very least, and will almost definitely need to upgrade your transmission yoke and driveshaft. About $600 for all that. And we haven't even gotten to improved tire traction.

So you see how it can add up? That $1200 kit has just become about $8,400 for everything I've just estimated. And that's IF you do all the work yourself. Additional labor for building up your engine should cost a few more thou.

It is just like the old adage, if you wanna play, you gotta pay.
Don't let that stop you. But don't be in too big of a hurry. And whatever you do, try not to add up how much you have left to spend. It can be disheartenning.

Other than that, if a 427 is what you want, then go for it.
But do read the post just before mine about living with a hipo engine. All those things can be true in your case. Your driver 350 Vette could easily be restricted to almost racing only with an upgrade to a super small block.
But a mildly built-up 406 on the other hand will give you the best of both worlds...without spending a buttload of cash on trick parts and machine work.

TeenagerWith74Vette
Senior Member


114 posts [100%]
Gonzales, La USA

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 Re: 427 SBC Questions (MoMo) Reply to this post

I have the good heads alredy, Dart Pro 1s. I talked my machinist the other day, the block work won't be too bad. I already have headers (though I'm looking at getting better ones) and a nice exhaust. I also have the intake, carb, electric pump, and so on. The oil pan I need is $200. I already talked to a cam ginder about a custom cam kit. I think I'll be ok on that.

I appreciate all of the help so far. I haven't made up my mind at all, I'm still weighing my options. I've also talked with someone that is iterested in my short-block, so that will give me some extra money. I'm just gona see how evrything goes. I'm not in hurry at all, I just get excited. Hehe
Thankn,
Jay
_______

350 4-bolt main .40 over
eagle rods
KB pistons
10.5 to 1 comp.
FluiD Dampener
284 Extreme Energy Cam Hydraulic
Harland & Sharp Roller Rockers
Dart Pro 1 Alum. heads 215 runners, 64cc chambers 2.05/1.60 valves
Air Gap Performer RPM intake
750 Holley Vac. secondaries
MSD Billet Distributor
MSD 6AL Box
Dynomax 1 5/8 ceramic coated headers
Turbo 400 "Built"
B&M 3000 stall
4.11 gears
Old 235 series tires
Best qtr mile time: 12.6 @ 106 with a 1.77 sixty-foot (With 3.36 gears)
3.36 Rear currently for sale.

17yrs old and lovin it!

bowtie racing
Senior Member


293 posts [95%]
HELSINKI FINLAND

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 Re: 427 SBC Questions Reply to this post


Monty awsome engine work!!! Best iv seen ever!

Could post pictures of those Carillo Ti rods you have?

Thanks ,Joni
_______

Joni http://www.bowtie-racing.com/

wheelsup
Senior Member


677 posts [100%]
Maryland

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 Re: 427 SBC Questions (MoMo) Reply to this post

MoMO,sound advise and insight when approaching a project like this.
Phil
_______

1991 Coupe L98,6spd,MiniRam
350cu,stock bottom end.N.A
NHRA/IHRA Legal 11.41/120 Bracket Racer

New for 2001: Th350 Trans.and 4-link rear suspension.New best
10.99@123.9 ...1.47 60'

2002: New best 10.98 @124.6...1.49 60'
Planning next engine.

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