327 or 377 for tube frame 1969 "Vintage Look" road race Vett

[hoffman900]

image.jpeg

Another traction data point:

SVRA Group 6 A-Production 427ci Corvette:

8" wide bias ply "vintage tread", stock suspension minus springs, sway bars, and shocks (bolt ons). Pushing well north of 700bhp

https://m.youtube.com/watch?v=lLrjOgtuzfE

A tube chassis car (3 or a 4 link) on 10" modern radials will have zero traction problems. Especially with a small block.

I attached a photo of the camera car.

[wyrmrider]

"Oil pans have been a worse problem than expected also."
I wonder if this is because of the ventilation between the crank and the track???

I thought I commented on this thread but do not see it
I built a 3 7/8 or 3 15/16 stroke 4 " bore motor for a Corvette Roadracer- So Cal many years ago- stock deck block
I do not think there is much to gain over 3 3/4 stroke compared to the worse rod ratio, less piston support at BDC (ring seal) - tall deck block is another whole issue
OP already has a block and rods
so without changing everything at once we're looking at a crank and pistons
I see no reason to limit to with a 3.5 stroke 377 (unless there is some rules reason) 3 3/4 gives about 400 cu inches I've built lots of 4 " stroke motors Drags- street- Class) but IDK about for Road Racing
Others have covered other aspects, the latest most wonderful heads etc
but you have to walk before you can run
as I said above I'd be tempted to run what you brung this season and get the chassis dialed in
I'd run the lash loop and advance/ retard drill and make carefull notes on where you could use more power, driveability (equally important)etc
I'd go here and fill out and also post all the info back to this thread- head flows etc
http://jonescams.com/road-race/
Mike will spec a different cam with different stroke and rod ratios even with same heads but he can give you an idea of what a cam change can do

BTW the vet ran several seasons then lost a chunk of mallory cutting the motor in half- my fault of course- took out the dry sump also
lots of ways to spend money- rockers etc

[MadBill]

...Another traction data point:

SVRA Group 6 A-Production 427ci Corvette:

8" wide bias ply "vintage tread", stock suspension minus springs, sway bars, and shocks (bolt ons). Pushing well north of 700bhp

https://m.youtube.com/watch?v=lLrjOgtuzfE

A tube chassis car (3 or a 4 link) on 10" modern radials will have zero traction problems. Especially with a small block.

I attached a photo of the camera car.

Nice car! I saw it at Mosport last weekend and meant to look it up in the pits. Seemed to be moving up fast in that big field Saturday, but I didn't see it Sunday (Maybe missed it; I got there mid-afternoon.) What sort of times did it run? I wrench on a Vintage-legal '86 Merkur but it turned out to be too fast to enjoy there so we run it in GT1.

[66Vette]

Mad Bill:

Thanks. Those aren't quite stock fenders....and I run a 5" back space on the stock trailing arms, that's about as far as I can stuff the tire inboard. I haven't really gone back to tuning the anti roll bars. I've been tweaking the spring rates to get the car more neutral. Fronts are now at 800 lbs/in, and the rear transverse leaf is around 480. That got the car balanced with no rear bar and a 1 1/8 up front. Maybe time to re look at the anti roll bars again. I race this weekend on the DOT200 tires. We'll see how much that upsets the car.

Cris

Hoffman900, very nice car!

[hoffman900]

The oiling issues are the fact they have to use a wet-sump. Bill-C shared they are seeing 1.5gs lateral, and 1g under braking. Hot oil is more like a solvent in viscosity then what we all think of.

Here is there not cheap solution: http://store.cobraautomotive.com/oil-pa ... mpetition/

MadBill, I mistakenly said it was a 427ci car, it's a 465ci car (revving to 7500rpm). Looks like it did 1:33s last weekend, but I'm not familiar with the new driver. The old driver (the shop owner's son of the outfit that built it) was typically a second or two faster than Peter Klutt is in vintage Corvette, if that serves as a reference to you.

The new owner posted pictures here: http://www.terrywatsonmotorsports129.com/343637966

[MadBill]

That's probably as fast/faster than anyone. I clocked a lot of 1:35s and higher..

Beautifully done in every detail!

BTW, I've had mixed results with those X-stream filter lids. If there's only room for a small conventional filter they can be a help, but if the cylindrical one is adequate, the lid filter seems to cause turbulence and often loses 10 or more HP...

Also, if legal, sealed cowl induction make a big difference on these cars...
<End hi-jack>
.......

[bosco]

I conversed with Mr. Woehrle from HSR when I started this project more than two years ago. He implied that I would likely fit in group nine with old IMSA cars, old and recent TA cars and the like. Maybe in the class with the old DEKON Monza. It could also run in SCCA GT-1 or SPO, but of course not competitively.

Bobby Kennedy one of our team drivers (sometime Trans Am 2 and Grand Am/IMSA driver) has lapped Daytona at 1:53 in a similar power to weight tube car with the same tire. Top speed in the tri-oval was 182.

The Hoosier 3035 is fast for about 5 laps then rapidly falls off about 1.5 seconds in a 30 minute race. The 3045 compound is a little slower initially but hangs on much better..it is the TA2 compound.

As I said, this motor has been sitting around for 4-5 years, I think I will just take it back to Byron Koury Racing Engines who built it and let them check it and redyno it. I know it is a good piece so it may just be a good idea to sort the car out with it, see what I have there and go from there. Certainly cheaper.

During the past 25 years I have gone from improved touring Datsun Z cars to E Production, to GTA stock cars, the tube frame C6 Corvette and now the old Camel GT look Corvette.

I love torque motors as they are so forgiving and relatively easy on the wallet as others have stated.

Again thanks to all, some very good and interesting points of view !

Bosco,

You should really determine what class you're building to. Is this a IMSA GT type build?

Jack Woehrle (HSR's Tech guy) has a forum here: http://www.vintageracerules.com Jack has and will pump cars for displacement.

If you don't know him, he's super friendly and will help you along.

The 10" wide tire can easily handle the power. The SVRA Group 6 (vintage SCCA B-Production and A-Production) cars are putting a lot more power than you through 7" wide tires. The suspensions are a lot more stock than what you should be using with a tube-frame set-up. It comes down to the driver and how good you are at setting it up too, ymmv.

Note: the 310ci BP Fords are pushing 595bhp+ with iron heads and a low rise intake, and have a fat powerband. They also redline about 700rpm beyond what your redline is. They're not cheap engines. Bill_C on here is involved with Cobra Automotive.

From Bill-C

dont think that it is fair to my customers to just give away all of the info and "secrets" that they paid dearly for, but I guess it would be ok to give a few general trends. I believe it is important to match the engine specs to the customers budget, the class that they are running, the skill level of the driver, the skill level of the mechanic, how much maintenance they are willing to put up with, and lastly, are they racing to win, or just have fun. Under ideal circumstances, 625 hp and 430 tq is "possible". To run at the front of the pack in the vintage road race world you're gonna need the highest compression ratio you are capable of tuning (at least 13-1), an agressive solid roller that has the best compromise of torque off the corner @ 5000 rpm and top end horsepower @ 8500 rpm. The heads need to have the highest velocity you can achieve and still flow 320 + cfm @ .750 lift. We're on our 5th revision to our head cnc program for the rhs castings for the sb fords and 3rd for the dart sb chevys. (I'm assuming you want to run B /P in svra with a vette). The performer rpm intake will need a huge ammount of work. You also have to make sure the valvetrain is very stable. The f@#$ing drivers ALWAYS come in from the track with tach tell-tales pinned.I'm told that a jerico trans will down shift from 4th to 1st gear @ 160 mph NO PROBLEM. Oil pans have been a worse problem than expected also.

In-car from CA's house car: https://www.youtube.com/watch?v=fB-1rEntau0 ... all purring along through an Elston built exhaust system.

[pamotorman]

Terrific looking car, and great work getting so much tire inside the fenders!

Have you tried stiffer on the ARBs?

when I ran autocross pretty successfully with a C-2 corvettes I loosened the ARB for quicker turn in which works well on tight courses. the foreign car clubs when they set up the courses always tried to handicap the corvettes with tight corners but I ended up with FTD more often than not.

[F-BIRD'88]

I would not cannibalize the 327 short block at all and going to just a 3.48" crank will not get you to your power goals anyway.
I'd build a simple and low cost 383 with a GM 350 block and a cast (scat or) 3.75" stroker crank.
Keep it simple and low cost. Keep the compression ratio 10.50:1 or a bit less.
Use the heads and top end from the 327 on the 383.
But get a cam for the 383. Now you can compare on track performance.
Keep the 327 as is as a spare. Now you got 2 good motors.
And no cannibalized stuff hanging around.

[cv67]

who cares about nostalgia there is not a nostalgic person out there to get warm and fuzzy about what he can't see inside your engine LOL

Agreed....better to remember your first romantic encounter than to have her today lol
Op at your age why hold back? There are good parts out today than can take a beating go big as you can afford. Winning is what its about create your nostalgic memories today!!

BTW that blue/white vette is drop dead perfect. wow.

[MadBill]

[quote="hoffman900"]...quote]


Here's a shot of "Frankie", a 1979 383" ex-Trans Am (sister to the '81 Series champ), ex IMSA, G70 VARAC racer I worked/consulted on for a number of years. Finished on the podium against contemporary GT1 cars in an AAGT event a few years back; best Mosport lap a 1:23.8.
.

[Alan Roehrich]

One of the best compromises is a 4.155"-4.165" bore and a 3.625" stroke, it makes plenty of torque without being too hard to hook up, and makes good HP. Seems to make cars really easy to drive. Will a more radical short stroke engine out run it? Maybe. Will more cubic inches beat it? Maybe. What you build depends on what your budget is, and what you're trying to accomplish, reasonably.

[crazyman]

OP, I'd keep the smaller motor that is rev happy for an SCCA car. Easier to pedal and better on a long straight as you can keep the same gear you need into the next turn.

[bosco]

After more than four years, the Outlaw Vintage C3 is making smoke. Should test this month... Went with the 327 I had. mhttps://www.facebook.com/photo.php?fbid=1021545 ... heateraybe at Sebring. [img]https://www.facebook.com/photo.php?fbid ... =3&theater

[mekilljoydammit]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.