Stall speed convertor compatible with 3 + 3/4 stroke for the motor?

[fasterthanu]

You learn something new everyday. I am having my 383 built, 500hp, and the speed shop asked me to find out if my stall speed convertor is compatible with a 3 and 3/4 stroke for the motor... Sounds like a very weird question since it is just a bored out 350. The transmission shop told me of course it will, it may stall just a little bit longer. I currently have a 2500 stallspeed in my 700R4 trans. I called the speed shop and told them what they said. The machine shop replied, we just did an engine for a truck. With almost twice the horsepower as the previous engine the truck only performed mildly better... I swapped out the stall speed, for one compatible with the 3 and 3/4 stroke motor and picked up just over 2 full seconds... So, I called the makers of the stall speed I currently have in my car, Midwest Convertors. They told me right off, that you can have two stall speeds, both 2500 rpm, one in a car with 500hp, one in a car with 250hp, and the 250hp might beat the 500hp if the 500hp car doesn't have a convertor that is compatible with that stroke... I never heard of this. He said that it can make this powerful engine perform like a dog. Wow. I figured, both are 2500, how can it make a difference? So, for you all with a 383 out there, and a 700R4, you might wanna find out if your convertor is compatible with your stroke. You may not be anywhere as fast as you should be...

 

[Glensgages]

I don't think you have much to worry about, unless you went to a high-RPM/low TQ 383" hammer.
By-nature, a long-arm 383 developes more TQ than a similar 350 by virtue of it's longer stroke.
From what I've seen, when the SAME converter goes from a 350" to a similar 383", the stall goes-up slightly.

I think you'd have problems going from a converter built for a big (454/502) motor, and putting it behind a high-RPM screamer (302/327). The big motor would prefer to 'grunt', using it's torque, where the 'mouse' needs to rev-up quickly...

I once had a 10" converter behind my 10:1 355" sbc (approx 420 HP; ran mid-13s) that stalled at 1500/1800 at the track.
A buddy borrowed it in a pinch, for his 421" sbc (530 HP?) in his 11-flat Monte Carlo. He said it stalled at about 2500+...until he shelled it!!!!!