TeenagerWith74Vette Senior Member
114 posts
[100%] Gonzales, La USA
|
427 SBC Questions |
5:09
PM 5/5/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
8:18
PM 5/5/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
8:52
AM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
11:36
AM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
12:12
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
12:28
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
12:39
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
12:47
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
1:10
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
2:38
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
3:27
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
4:02
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
4:34
PM 5/6/2002 |
| |
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 Moderator Cruise-In III Veteran
2729 posts
[100%] Morrison CO
|
Re: 427 SBC Questions
(autoxer) |
6:14
PM 5/6/2002 |
| |
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 Moderator Cruise-In III Veteran
2729 posts
[100%] Morrison CO
|
Re: 427 SBC Questions
(MoMo) |
6:24
PM 5/6/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
8:29
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(HunterRose) |
9:00
AM 5/7/2002 |
| |
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 Moderator Cruise-In III Veteran
2729 posts
[100%] Morrison CO
|
Re: 427 SBC Questions
(HunterRose) |
9:08
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
9:16
AM 5/7/2002 |
| |
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 Moderator Cruise-In III Veteran
2729 posts
[100%] Morrison CO
|
Re: 427 SBC Questions
(MoMo) |
9:21
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
9:35
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
9:52
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
10:03
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
10:18
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
10:22
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
11:08
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(Monty) |
11:14
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions (clem
zahrobsky) |
11:22
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
11:51
AM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
12:35
PM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(TeenagerWith74Vette) |
12:59
PM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(thejaf) |
3:26
PM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
3:52
PM 5/7/2002 |
| |
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
|
Re: 427 SBC Questions |
2:42
AM 5/8/2002 |
| |
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
|
Re: 427 SBC Questions
(MoMo) |
4:49
AM 5/8/2002 |
| |
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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