OK, I am swapping out the wheezy 305 in my '86 FB for a nice new 350. Should be a big increase in both torque and HP over the old 305. The cam manufacturer (comp cams) says I'd should get a converter that's stall speed is a few hundred rpm over stock - which probably works out to around 2000 rpm but I'm not quite sure.

Based on reading, I see that any torque converter will stall higher if the engine it is attached to makes more torque. This is the case with my setup. So the question is, do I really need to change it out at all? Why not keep the factory converter and it should stall somewhat higher than it did with the 305, right? Anyone know for sure?

Tranny is 700R4, factory stock - lots of miles on it (185,000).

thanks

 

It really depends on your duration at .050 and lobe separation this determines how the cam will make the engine idle.
It sounds like your transmission is going to go out soon after the power increase since it has so many miles on it. You definatly want to get a new converter,because of the clutch, when you get a new trans and you can get one with a higher stall at that time. I've seen a book with stock GM converters that stall from 1200 up to 2000 depending on application.

 

It really does depend on the torque of you engine but if you have an engine that will pull it up 500-600RPM your tranny (and converter) will soon give out anyhow. You are probably talking 100-200RPM. There is an excellent converter available at your GM dealer that will stall @2000 RPM and is of the highest quality. It is p/n 24202310.

 

I really don't know how much HP or torque the new engine will be making. I measure/calculated close to 10:1 compression (static) and will be running vortec heads and a comp cams extreme marine camshaft. I hope for 300+ hp, and think it will have more than that - we'll see.

Well, that's at about twice the HP of the old 305 - I think they made around 170 or so - so I suppose that's going to weigh in on the choice of TC.

The cam shows the power band starting at around 1500 rpm up to 4500 rpm (off the top of my head). The tech guy at competition cams recommended a TC that stalls a few hundred rpm over stock. I just don't know what the stock stall speed is! Ha.

Question is, what HP/torque levels is that GM TC good for? Second, what will it be like to drive with a stall speed at 2000 rpm? BTW, what is the stock stall speed?

One more question: - not that I fully grasp the concepts but is the TC a lockup style, like the original?

gene

 

That converter has the same internals and stall as the Corvette converter so it will be fine at your power levels and yes it is a lock up.