Webdoc

Hey Guys. Into year 2 of my rebuild on a 67 coupe with a 289 and C4 transmission. Rough sheet metal work now finished up I'm concentrating on the drive train this year. I've got the engine torn down and prepping it for a trip to the machine shop so I'm turning my attention to the transmission.

Here comes the question. I've never really worked with an automatic before. In fact, the only vehicle I've ever owned with an auto is my daily driver F150. I've been reading about choosing a torque converter and am really getting confused when it comes to picking a stall speed and such.

This project is going to be a daily driver with a little bit of extra muscle under the hood. Any suggestions on what I need to be looking for? Anyone able to explain the concept of stall speed to me in practical language I can understand? Thanks guys! Don't post much but this forum has been invaluable to my project so far.

emttrevor

a stock converter is anywhere from 1300-1700 dependent on the build of the engine to start. When you buy lets say a 1500 stall its like a clutch on a stick shift in a way, when the engine is below the stall speed say 1200rpm its like having your foot half way off the clutch the car will still drive but its slipping and isnt fully locked in once you get above 1500rpm it locks and diverts full power to the tranny then in turn to the rear wheels. The higher the stall the more you will feel this also ( usually on a stock converter you dont feel this at all) . Once you get above a 2500 stall its like cruising with a slipping clutch at low speed it doesnt do any damage just takes a little getting used to. A high stall enables you to rev the engine to a certain rpm before power locks so you can do brake stalls and spin the tires..lol gives you faster times off the line. I have played with different stalls and unless you are going to put 400 plus hp I wouldnt go over a 2000 stall. Stall speed itself is an individual choice dependent on rear end gears and hp of engine also as well as style of driving. Also the higher the stall the quicker your tranny fluid will heat up and wear out so you will probably need to put an external tranny cooler on which is cheap... So in laymans terms the higher the stall the quicker your engine can spool power to turn the wheels faster at take off. In real terms a transmission shop would have to know the hp of the build the cam specs, the tire size and the rear end gears you are going to use as well as the use its going to recieve to give you the correct stall you need, me personally I like a 2000 stall for a mild street build, gives you the best of both worlds and doesnt adversly affect the life span of the tranny...

Iskwezm

thats about the only answer you need^^^^^^

frdnut

I agree with most of the above post but 2000 rpm is a pretty mild convertor..Depending on how hard you want the car to take off and probably most importantly your camshaft specs you may need more...Another thing the extra stall speed does is allow an engine with a "big" cam to not fight against the convertor and will let it idle easier....Again depending on cam specs this may not apply to you..

jojobanks

a lot of it depends on the cam, so posting the specs for that would help, but unless you're getting a pretty radical camshaft, I wouldn't put anything over 2k in a daily driver.