I own a Stock '78 corvette as of now, but am working to build it up. I think it could possibly need a new torque converter because try as i might i cant get the wheels to spin [power breaking] and i know with the L-48 i should get about 280ft-lb torque. is this because of my converter? or could there be more. Anyways in replacing that i need to know my transmission type. i htink its the TH-350 but i really have noidea. im new at the whole car thing so to speak. any ideas?

 

has it had a "good" tune ???? you want to change it so you can spin the tire's ???? maybe you have good tire's that hook

 

as far as the tuning goes im not sure i just got the car about 6 mo ago. The tires at SIGMA SUPREME TRs.

 

The torque converter is waaaaay down on your list. First up is the exhaust system. Take a look under the car. Does it still have a single exhaust system with a big ole catalytic converter? If so, you need to go to true duals. Unless you have smog testing...in which case you'll simply want to replace the cat with a high flow unit.

Do this, then get back to us for the next steps!

 

What size tires...255-60-15, if so, it's very hard to spin them...even with more muscle...

 

I did open it up to true duals about 2 mo ago, and have Chrome ceramic long tube headers in the mail as of right now actually.

 

Lower rear gears will help more than anything. Trying to over power a 3.08 gear in order to smoke the tires will be more expensive than a gear change. Pick your poison.

 

big tires and high gears don't add up to wheel spinnin.

 

Okay...that's done! Heads and cam are next on the list...

 

on my old 77 L48, th350, 142 hp, 242 ft lbs i couldn't get those tires to spin unless i was going around a turn from a dead stop.....on sand...you are simply lacking the power to spin them....sorry...

 

ok my tire size is P225/70R15 100T. so i guess that may be the root of the problem. As so the 77, i doubt my car is in as bad shape as that. it has 78000 on it and the engine is in great condition. used to be a show car. im guessing it has around 200 hp and 290 or so torque although that is just me guestamating from what ive done to it from the stock specs.

What cam? i really dont know where to even start looking for something like that.

 

my figures were RWHP measured on a dyno....you would be surprised what a reality check the dyno is.....

 

ah ok i thought you meant engine hp. so would torque converter be a way to convert more of that hp into Rw ?

anyone ever run a stock c3 in the 1/4 mile ? mine did 15.3 the other night.

 

Some may be in your technique but most of it is that you don't have enough horsepressure (torque, really) to get the job done. The truth is that your static clamping force of your brakes is much higher than your applied axle torque.

If you insist on "power braking" then you might try varying your brake pedal pressure. Standing hard on the pedal makes it very difficult for a modestly-powered car like your to turn a tire. You might also try a hard stand, floor the throttle, slightly release the brakes so that the car rolls a couple feet then applying the brakes again. It's easier to get the tires to turn if you get them moving just a bit. But don't expect a Pro Mod, engine screaming off the limiter, up through the gears burnout. It's still going to be pretty pathetic. You'll make some smoke and noise but nothing to write home about.

If all you want to do is brake burnouts, a higher converter stall is the best method to get there. Up to the point of lockup, a converter multiplies torque by about 2:1. If you raise the brake stall to the point nearer your torque peak, you'll have a lot more torque to apply to turning the tires. Doing it by throwing engine parts at it is not only the hard way, but it's a lot more expensive. Now, this advice is based only upon your question about doing brake burnouts. It has nothing to do with improving combustion efficiency or pressure.

 

I feel your pain.
I've got a 74 L48 with a few mods.....Cam, intake, carb....blah blah blah....chambered exhaust, 2500 stall and still get little wheel spin.
My 255-60-15's really hook up.

 

anyways, anyone know what the transmission type is ?

 

Show us a picture of your trans pan. If it is square its a th350. I believe all L48 came with a th350. Your stock stall should be 1600-1800. Biggest bang for the buck would be a gear swap to 3.55-3.70's.