I am putting together components to upgrade my 1980 l48 Corvette and have a question about torque convertors . I have a freshly rebuilt (3000miles ago) l48 with the addition of headers, edelbrock performer intake and Holley 750 carb. I intend to add a Howards roller cam part #K113215-10 that has the following specs duration 270/ 278 and duration at .50, 217/ 225 with a lift numbers of .495 / .500 with 1.5:1 rockers. As well as some aluminum heads with 64cc chambers 2.02 intake and 1.60 exh valves. My question is what stall speed would work well with this combo. I want to maintain good drivability so I don't want anything radical, Currently I have the stock Th 350 trans with the stock convertor. Also what is the stall speed of the stock convertor in the 1980, I couldn't find that spec anywhere. As always any advice would be greatly appreciated. Thanks Gil

 

I believe stock stall converter was 1600-1800

I have a 1980 with a 383 stroker and TH350 w/ Trans-go shift kit and my transmission guy recommended a 2200 stall so that's what I went with. I haven't driven it yet since going thru a restoration so I have no seat time to talk about.

Richard

 

Since you have headers. You don't want the bending required to run the pipes through a stock cross member

 

What's your budget and how do you plan on using the car? The reason I ask is because modern aftermarket torque converters like Yank and Vigilante, while expensive, deliver excellent driveability. While I was going through the process of hopping up my 96 impala ss, I installed a converter intended for a truck with a stall speed of about 2500 as I recall, pairing it with a Crane cam similar to the one you're thinking of using. It worked OK, but as I was racing the car every week I eventually stepped up to a Yank 4000 stall converter. It actually drove better than the truck converter. The only 'driveability' issue I had was I had to press the accelerator about a quarter inch further down to get going. No mushy feel or anything like that. I drove that car daily for 10 years with the 4000 stall converter on it.

The TH350 trans doesn't lock the converter, does it? You probably wouldn't like the 4000 stall due to how crappy it would make your mileage, but a GOOD, MODERN 2500 stall converter would drive better than your stock one and handle the cam just fine.

 

The 1980 should have the TH350c which supports lock-up functionality if its hooked up.
Richard

 

Gil, you must not be familiar with roller cams. Roller cams can be 8+ degrees larger in duration than the H-flat cam counter part and have more vacuum and a smoother idle. The 1980 L-82 h-flat cam was I/E 222/222; .450/.460 on a 114 LSA. Extremely mild non performance cam. A roller cam in the mid 220's is extremely mild.

As to stall convertors you can get bad advice all day long from people that install cheap inefficient junky TC's. Advice from someone that has never owned or driven a high end TC is like asking a second grade kid for advice! A quality TC can last a life time even behind powerful engines. I drove around in my vette for many years with a 3800 stall 9.5 inch Vigilante is a great TC. and I have installed them. I actually used a Art Carr the business not the person $1100. At freeway speed cruising it had very little slip. In years past I had something like a B&M hole shot 3000 stall and that piece of junk had the motor always doing 3000 rpm unless you actually went fasters. I went through all kinds of TC's when I was young and dumber. They actually didn't have these new designs way back when. Waste of power and a heat creator.

Since you won't ever have catastrophic failures like cheap TC's and because of the high efficiency I always recommend 3000 or higher. Because power is addicting and in the future you might have a more radical motor. I don't even count the number of motor combinations I went through before landing on my 434 ci Motown small block solid roller 7500 rpm motor.

 

I intend to go with shorty / tight tuck style headers when I add the cam and heads. Thanks

 

The cam will normally tell you the recommended stall, but you can always go bigger, ESPECIALLY if you're going with a lockup TC. Then you can have fun torque and acceleration via a bigger stall and still get good gas mileage and keep it cool via TC lockup. -If you're going with a higher stall, definitely consider getting an external, dedicated trans cooler and ditch the one integrated to the radiator.

My notes say that the stock L48 stall speed was 1,650 RPM and the stock L82 stall speed was 1,800 RPM.

I have a static CR of 10.2:1 with my 64 cc aluminum heads and a roller cam with 227/228@ 0.050"; 355 rear gears and I went with a 2,400 RPM stall TC in a 4L60e but I've got a very torquey low 1st gear. I'll see how well it hooks up when I I complete my own head and cam swap this winter, but I'm secretly trolling CL aggregators looking for a good price for a 3,000 stall Vigilante... I can say that they sell VERY quickly on the second hand market.


Adam

 

Shorty headers are just a flow improvement over cast exhaust systems. They are not a tuned diameter and length. They are in the same category as side pipes. Read up on header science online.

 

I guess I should've been more specific as to my goals for the upgrades I plan to my new to me 80 L48. I don't intend on ever racing the car, it will simply be a Saturday cruiser with good enough manners for the wife to enjoy driving it as well as maybe an occasional short road trip. My background is more in building motorcycles mostly V-twins the last few years. As I have advised many friends seeking more from their bike, Horsepower wins races, but its torque that puts the smile on your face and wins stoplight to stoplight. Most people with high horsepower engines that don't race, never get anywhere near the RPM level required to experience all that horsepower they paid for and brag about. I have stuck to that advice and have yet to have a friend disappointed in the outcome of his build.
So drivability in normal traffic and a good strong torque curve that comes on early and lasts thru around 5500 RPMs at the most is what I'm shooting for. As always thanks for all the advice there are a great deal of you that I have already learned so much from.
Thanks Again GIL

 

Don't waste your money........the long tubes are proven to make much more power dollar for dollar........they go in easy from the bottom and any competent muffler shop can snake them through the holes in the crossmember....
This is my opinion....the shorty type headers barely flow more than the stock Ram Horn style......this is fact. The reason that long tubes work so well is the scavenging they provide for the cylinders via pulse in the collector.

Jebby

 

What he said. .