632C2

I recently removed the TH400 clutch setup from my car and went to a torque converter. I decided not to use a trans brake and instead I am foot braking the car. First time out (8/25/2022) I managed a 9.47 at 143.96 while pulling the front tires off the ground about 5” and the engine sputtering through 1st gear. After that race I talked with Will(rklessdriver) about these two issues. He came up with some ideas right away. I shared a few videos with him and he was able to give me shock settings and carb ideas that he thought would help. I went to work making these necessary changes.

On 9/22/2022 at Pacific Raceways the first run off the trailer was a 9.22. At the launch the tires didn't come off the ground and there was no sputtering. The next 5 runs were between 9.15 and 9.18. My best 60 ft was 1.289. I had never felt a car pull this hard in first gear! The next day I emailed Will to report my results and to emphatically thank him for his help. I once again sent him a few videos and after he examined them he gave me more recommendations for shock adjustments to use the next time I go out (next season). We are very fortunate to have someone in our Corvette community like Will that is exceptionally knowledgeable and extremely helpful!!


Here is some background on the car. It's a 1967 Corvette coupe. I am still using my same stock appearing motor that includes a factory Chevrolet Tri-Power intake with (3) two barrel carbs, factory cast iron exhaust manifolds, and a full exhaust with mufflers out the back of the car. It's a 582" naturally aspirated BBC using a Chevy Bow Tie block, 4.600” bore x 4.375” stroke. I have gone through a great deal of work to have the engine compartment appear the same as it did when the car was built in 1967. I went so far as to take a current set of Dart heads and make them look like the original factory cast iron heads. Since I have the car's original 427 I was able to make patterns of the factory heads and went to work with my grinder's on the Darts.

The rear-end setup is a Mike Dyer built Tom's 1480 12-bolt conversion with 3.73 gears. Mike did all the machining to get the 12-bolt in the case as well as setting up the gears, posi, and inner axles (is there anything Mike can't do?). Tom's 3.5” halfshafts, outer axles, frame reinforcement, upper control arms, and safety loops are also being used. I modified a pair of factory trailing arms to allow for 15 x 8 wheels with a 6” backspace. Dave Ogden supplied us with the jewelry-like diff caps and the u-joint caps.

I have been running a clutch turbo 400 transmission in this car since around 2016. For those not familiar with a clutch turbo 400, the torque converter is replaced with a clutch setup. The best times with the clutch turbo 400 were a 9.63 et and a 148.14 mph. The best 60 ft was a 1.585 but all others were in the high 1.6's, 1.7's, and worse. I could never get the car to launch consistently. I either left the line slipping the heck out of the clutch or the tires just spun.

Will was able to get me a set of double adjustable Viking shocks for all 4 corners of the car. He gave me detailed suggestions on where to start settings wise and what to do based on how the car was reacting. Unfortunately my inability to have any kind of consistency when leaving the line didn't allow his suggestions to be properly put to work.

Well I was finally done with the clutch turbo 400 and contacted Neal Chance Racing Converters for some ideas. I talked to Doug and my gosh does he know his stuff! We went through all of the data from the time slips, the Racepak data acquisition, and the DynoJet. He ended up suggesting a 9” bolt-together converter with approximately 6000 rpm stall. Doug made sure to tell me to call him once I got a few runs under my belt to go over the new data. When I told him I have a DynoJet at my house and that I use the crap out of it he told me to expect as much as a 100 rwhp loss vs a manual transmission! I told him I didn't care as long as the car would go quicker and I could get some consistency out of it. I also told him about the time I had the 632 in the car with a Coan PG and lost 100 rwhp. At that time I wasn't racing the car so I removed the PG and went back to a manual trans.

I immediately went to work and took the clutch turbo 400 apart, replaced the forward drum along with it's clutches, replaced the front pump, installed new teflon seals, set up all the clearances, installed a new JW UltraBell, and then installed everything back in the car.

I put the car on the DynoJet and instantly lost approximately 70 rwhp! The car was making around 740 rwhp with the clutch turbo 400 and it dropped to 670 rwhp with the new torque converter combination. Again, I didn't care because I was convinced the car would go quicker.

I am now on a mission to get in the high 8's. I think if I can find another 30 rwhp while keeping the stock appearance and apply Will's shock recommendations I might be able to get there!

leigh1322

Awesome car!
Please keep up the info for the rest of us.

76strokervette

Congrats Steve! I think you'll be able to tweak a little more out of the 67. Let me know if you need anything.

Rescue Rogers

How about pics of the car, your engine and the rear end setup...Sounds incredible. Is the inside gutted? how much does she weigh? Are you running slicks, wrinkle walls or street legal slicks????? Are you using a rectangle port or oval port intake? Stock tri power carbs?

427Hotrod

Wow Steve!! CONGRATUATIONS!! That thing is flying! You've got suspension working very well!!

One of these days I ought to put an auto behind my turbo combo....naww.......probably not!!

Again..fantastic work.....your car is amazing!

JIM

gkull

Very impressive, but what exactly was changed? Like higher pound rear springs.

Jim's seems to carry the front tires off the ground 🤪

BKbroiler

Wow that performance is amazing, especially considering the 3 two barrels and the stock appearing exhaust manifolds.
Five runs between 9.15 and 9.18 is surprisingly consistent. You could do well bracket racing that car. You just need to work on your reaction times, LOL.

7t9l82

When you consider the fact that in the mid 70s I ran a not very often competitive pro stock car that ran. 8:60s at 160 ish mph your car is astounding.
Jim Beaty at ATI BUILT several clutch turbos for me but the told me to hang it up and move to the Lenco like everyone else.i never looked back. Well now I do 😂.
Keep up the good work. Guys today have so much better stuff to work with. I didn't have to make my aluminum heads look factory. Because they were, with alot of work.
Good luck!

632C2

Thanks! Will do!

Thanks Dave! Nothing right now but I will let you know.

I will post some pics shortly. The inside is totally stock appearing with the unfortunate addition of an NHRA 8.50 certified roll cage. I haven't weighed it in a while but it was 3402 the last time had it weighed. It's definitely under that weight now. I am running Micket Thompson ET Street Radial Pro's. Rectangular port heads. The tri-power carbs are not stock. I am using a Holley 4412 center carb and 4365 or 4783 end carbs.

632C2

Thanks Jim! If I was half as good at shifting and controlling a manual trans car like you I would have stayed with a manual. What you do is truly amazing!

632C2

Will had me tighten up the extension on the front shocks by quite a bit while I was able to keep the rears where he had instructed me. Yes, Jim's car is on a whole different level that is far above mine!

Thanks! My reaction times do indeed need a lot of work. Hopefully next season.

Ah yes, I remember those good old days fondly. Thanks!

632C2

Here are a few pics.

rklessdriver

Car is absolutely amazing Steve. All the attention to detail.... the hindrances to going fast you purposely kept. Its the challenge of it, much like the class racing I do with my personal car.

Like I have said before many times, I really enjoy being able to help. You have a really good piece and honestly its a privilege to be a part of making it all it can be.

I'm looking forward to what you can do next season.
Will

ML67

Congratulations Steve! Your hard work, attention to detail and shrewd approach have resulted in an amazing result!

How does the TH400 shift lever fit in the console - has it been converted to the stock appearing auto console?

Last question - what are you looking at the get it in the 8s? I have little doubt that you'll achieve this.

Cheers!

Mark

Rescue Rogers

What type of exhaust are you running? Those manifolds and thats it or to a collector and out the sides?

A10pilot

WOW

632C2

Again thanks for all of your invaluable help. The car wouldn't have been this quick without you - period. I am looking forward to next season as well!

632C2

Thanks Mark! I have taken a Hurst Pro-Matic 2 and welded the factory 4-speed shift handle to it. I made brackets that allow the Hurst shift mechanism to remain under the console while the factory shift handle, ball, etc sticks out just like stock. I have left the clutch pedal in the car with springs to keep it from hitting the floor.

As far as changes to get in the 8's, that's a great question. I only like to work on one project at a time. A few months ago I bought a LS427 crate motor from Chevrolet and I am getting ready to put it in my red '67 convertible. That is going to be pretty time consuming so when that is done I will get back to this car.

632C2

I opened the outlet of each factory exhaust manifold to 3" on my mill. From there it transitions from 3" to 3.5" clear back to the transmission crossmember. Next is a 3.5" X-pipe followed by another transition back to 3". The mufflers are also 3".

gkull

So on those 8 inch wheels are you able to put on something like 10x28 slicks? I was also wondering if you are using a trans brake for launching up near the 6000 rpms?

I was surprised by the bolt together 9 inch TC. the only time I ever saw those was on a blown alki dragster and they were inspecting it after some runs. Th400 with an aluminium Rodic 410 class SBC.

I imagine that you have some kind of spragless billet stator in yours