Hello gentlemen, Im ripping out the 8.2 Chevelle c-clip rear which is in my 71 skylark race car now, due to a slipping posi. The car has a built 430 engine with a hyd 240/253 542 lift Scott Brown Cam but with solid Chevy Lifters, rev limiter set at 6000. I was driving this car on the quatermile, but the th350 transmission and rear was slipping badly, so I dont have quatermile times that are helpful to choose a proper rear end gearing. 13.1 at 92mph at 6000.... with 4.10 gears ou: the skylark is empty, has lexan windows and the fiberglass hood will be installed soon, no exakt weight of the car. rear tire size is 28x10.5x15, but will go to 30x10.5. this is a low budget race car only, i have a 8.5 BOP rear here to start with. Im going with a Motive gear full spool, but which rear gear would you guys recommend me? Was thinking about 3.73? thank you! Bastian
If its a race only car, I would put the lowest gear in that will get you through the traps in your power band. Of course your tire height will also dictate what you want to run. If its a street/strip car, then you will want to be a bit more conservative, and gear selection would also selected on either the emphasis being street or strip.
Guten tag Bastian. Your right about something slipping if your only going 92mph at 6000uzzled: Unless you are spinning the tires through the traps, it sounds like the trannies fault. On the gears, if its a race only car 3.73s sound to high. I would go with 4.11s or 3.90s. I hate to give advice on a setup Ive never seen run, but 3.73s are what you would use in a street/strip car, not a race car.
You can play with some of the calculators here and maybe get petty close.. http://www.wallaceracing.com/Calculators.htm
Thanks for the replies so far. Its a race only car. The problem really is, I have NO clue what this engine/weight combination is capable in mph?! Guten Tag Madman: No there was no tire spin at 92mph! :grin:
My Skylark is set up about the same as you stated yours to be and until I got a good converter in it I was running about the same times. Once I got a good converter thoes times dropped to low 12's and with some more weight loss it would be in the high 11's. I have video taken from inside the car and you can hear the slip in the drive train.
The trans is already apart and will be rebuilt, converter will be replaced also. so hopefully i can bring all the power down to the ground in 2013. ---------- Post added at 01:55 PM ---------- Previous post was at 12:44 PM ---------- here the 430 powerhouse which killed the trans and posi...
500 HP would cross the traps between 110 and 120 MPH depending on the actual weight of course.. 6000 rpm 30 inch tire 115mph = 4.66:1 gear I dont think the calculator allows for TC slippage, so you better stay below that.. http://www.wallaceracing.com/calcrgr.php
I dont want to go through the traps with 6000rpm (due to stock rods), so with the 30in tire the 4.10 sounds better, with a 28in tire a 3.90 gearing sounds even better.
30" tire I would try a 4.10 gear since you wanna keep the revs down. Keep your eye on that 8.5. You start punishing it with slicks and a healthy mill and bad things might start happening.
I know the 8.5 BOP will be the weak link, but I have to work with it since the rear is what I have and theres no budget for a 12 bolt or 9". And finding one here in Germany is even harder...
Didn't realize you were so far away. Getting the converter right will be the key. I think the 4.10 will be about right assuming the converter is close.
As I read some threads about the right torque converter, a lot of people are recommending Jim Weise. But I think it would be helpful to know the exact race ready weight of the car, to find the perfect converter?!
We went to 4:10's and went back to 3:42. Our race cars liked that much better. No real effect on times, kept the revs down. We had a 28" tire, same as you have now.
Yes you definitely need actual weight for the converter. This is the most important piece of the car and needs to be as close as possible. The more information you can give the converter guy the better. In regards to the 3.42's I know you guys were spraying the black car right? Nitrous cars like less gear as do blower cars.
Yes, as far as I know Tylers race car has been running on juice. I have a complete nitrous setup ready to go, but Ive decided not to spray the engine.
We had 100 shot for a while. We have a bunch of 1/8th mile tracks and thought the 4:10's would be fine. But even without spray, times were better on the 3:42. Never tried 3:73's
Thats the big question.... Its really just a guess, I can give you the engine specs but no numbers. Its a 1968 430 Block .030 over and decked, Ive done the oil mods and blocked of the oil passage to the rockers, smoothed the whole lifter gallery, 1971 Heads with std valve sizes, decked and ported. Dual valve springs with 325 open pressure. After decking and cutting valve reliefs into the pistons, I came out with real 10 to 1 CR. Rod and mains are Standard size, stock rods shot peened at work and re-sized with ARP rod bolts. Sp1 Intake ported and matched to heads, 2in open Spacer, 1000cfm Troy Patterson Holley Carb 76/86 jetting. 1 7/8 open headers. Custom grind hyd cam : Dur @ .050 Int 240 Exh 253 Lift 1.6 Int 542 Exh 542 Advert. Duration Int 283 Exh 304 Lobe Centerline Int 105 Exh 113 Lobe Separation 109 Intake Lobe came out at 105,5 after degreeing the cam. Im running Chevy Solid Lifters 2900-16, lash set at .006 ! TA 1.6 roller rockers. maybe a 440hp? The car will go to my friend for weighing when the new rear end is installed, but he thinks it will be around 3000 to 3100.
