Hey guys,  I want to replace my stock torque converter in my 72 with a stall converter and I am trying to figure out the best stall speed to order.  Currently, my freshly rebuilt 350 with a 222 duration cam is wanting to pull me down the road at 20 mph at idle with my foot in the air....Also, due to a somewhat lean idle mix (due to the low vac....) the engine wants to quit when I put in reverse since  the converter is putting such a load  on the engine .(vac goes from 15 inches in park to 10 in reverse or drive).....

So, to make a short story long, my question is, will a 2400 rpm converter for example, ease up on the load it places on the engine at idle (850 rpm in park....650 rpm in drive)..Some have said yes,others say you have to go over 4,000 rpm before you influence the idle characteristics....since I drive it more than I drag it...I don't want an anoyingly high rpm converter..

Any experience out there on this?  I was leaning towards a B&M 2400 tork master...

Thanks, Bill....

 

 

The "problem"  for a new torque converter that I

4000rpm "stall" speed will effect the idle?
First...the "stall" speed of the convertor is the max speed(rpm) you can get from the engine with your foot on the brake, and your foot hard on da gas. (A simplified explaination, for sure, but easy to understand.)

If you were to put a 4000 stall TC in there, your car wouldn't even MOVE until you had yer foot halfway to da floor!

For a street driven car, I would stay in the 2200-2400 stall range, 2200 being best. This will definitely allow you to idle, in gear, with no unpleasant aftereffects. Stock stall speeds are in the range of 1100-1500rpm for most V-8s.
Stall speed is dependent on torque output, as well as rpm, and convertor size(O-Diam). If you put a 2000rpm stall convertor in a stock small block, you may see a 2000rpm stall speed. Put that same convertor in a big block, and you're likely to see a 3000 rpm stall speed.

What rpm does it idle at with it in park?

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Joel Adams
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Thanks Joel, that range is what others have been suggesting too.

idle is 850 in part and 600 in drive..

Yup...600rpm idle/in gear might be a bit too low. Does it "bang/jerk" when you put it in gear? I'll bet it do.
A slightly looser convertor ought to work fine.
You will notice a definite difference in normal take-off, also. It might feel like the trans is slipping a bit, but it's not. It's just the converter working at a higher speed(rpm).

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Joel Adams
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Just a followup to this thread....I installed a 2400 stall converter and it really did the trick...now I can slip it into reverse at 1100 rpm (when she's still warming up) and I only get a slight rpm drop and slight tug on the engine...just enough to get out of the gararge...then nice smooth power.

The stock convertor, and the replacement, are not lock up convertors.  As far as the sound, it could be convertor design, or the fact that you are driving in second gear when it's not necessary, and winding up the drive train a bit more, which will happen with light throttle.  Just shift to third until you think you will need the extra ummph.

A whine in only one gear is normally a planetary noise, but...some convertors do have a whine to them. I would contact whomever you got it from, and at least make them aware of the noise, in case it takes a dump on ya in a few days/weeks.

Then again, if you spend a lot of time in 2nd...you may very well have a front planet damaged/worn...

Also...if the new convertor is not bolted in correctly, or has too much space between the TC and the flywheel, they will whine...or, more likely, the pump will start to whine. Some convertors need to be shimmed between the flywheel and the convertor, to make sure the convertor is all the way meshed into the pump gears. Adams' Apple2006-10-04 18:44:22

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Joel Adams
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Joel and Ken,

1/2 inch?!?!? you're lucky that thing ain't already busted the pump gears!!

You should try to get about 3/16ths to 1/4 inch clearance between the flywheel and da convertor pads on a "normal" convertor, meaning one that has not been cut open and rebuilt.
You can use flat washers, but make sure they are all the same(exact) thickness. You want to put the TC all the way back into the trans, and measure the clearance. We don't want to pull the convertor forward, out of the pump gears more than 1/4", 5/16ths" MAX.
If there is that much clearance(1/2") between the flywheel and TC in your car, and you move it rearward with the washers, you may be moving it far enough to allow the pilot on the convertor to pull too far out of the crankshaft, creating a new problem!
Try the washers, and see if the noise goes bye-bye. We have been able to use up to 3 flat washers in some instances, without bad doo-doo happening.

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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Gap was not quite 1/2 inch, but I put two washers in and got it within a 16th....IT WORKED!  now it's quiet as a mouse...THANKS EVERYONE!

You're such a whiner!!!

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"