Stall Speed for Torque Converter '83 700R4

[Burban]

It's a 2WD 1/2 ton (C10 Suburban) w/ a 350 V8.

I'm wanting to put a diesel in, and I have heard different versions of what the stock stall speed is, everywhere from 1200 - 1800rpm. Did they put different converters in for the 6.2 DD?

 

[Burban]

Nada?

 

[bucket]

I think the diesel converter stalls a little lower. Might not be noticeable. I also think it might have used 6 lugs instead of 3? Or maybe that was just on the th400.

 

[MikeB]

Well, typically an engine that makes a lot of torque at low RPM doesn't require much stall speed. A company like Transtar will probably have the T/C you need, but they may not know the stall speed. I doubt GM would have even published that spec.

https://www.transtar1.com/products

I bought a rebuilt stock T/C for a TH350 from their Dallas store with a 4 year warranty (!) for around $65. I had an old one in unknown condition that I used for a core, but the charge would have been really low, like around $15-$20, as I recall.

Another point: Since diesels tend to make peak torque below 2,000 RPM, a higher stall speed T/C will simply be a waste of fuel and overheat the trans fluid. And it will never let the engine operate at its peak torque RPM.

 

[highdesertrange]

make sure you get the correct flex plate. a gasser will bolt on but is incorrect. a 6.2 is externally balanced a gasser is internally balanced. highdesertranger

 

[Burban]

I'm not really up to speed on auto trans, flex plate?

 

[highdesertrange]

flex plate = flywheel. highdesertranger

 

[Burban]

Yeah some googling and looking up part numbers for a 6.2 vs. a 5.7 clued me in a little, but why does the balancing matter? I thought the harmonic balancer was on the other end of the crank on both? Why do they have different flexplates, is it gearing for the starter?

 

[highdesertrange]

a 6.2 is externally balanced. both the harmonic balancer and the flywheel/flex plate balance the motor. BTW on a gasser the harmonic balancer is to lessen the harmonics on the crank when the cylinders fires. it is not to balance the crank. the crank is balanced internally. on the 6.2/6.5 the balancer has a dual function to smooth the harmonics and to balance the crank. the flywheel/flexplate is the other half of the crank balancing. 6.2/6.5 cranks are not balanced internally. btw the harmonic balancer on the 6.2 needs to be in tip top shape. if it's not you will break your crank. make sure you have a good quality balancer. if your balancer shows any sign of age replace it. I like the fluid dampeners as they eliminate all the problems associated with standard balancers. highdesertranger

 

[Burban]

So is the flexwheel specific to that one engine, how does that work when you replace it?

I understand balancing as a misnomer for damping, but you mean balancing like a driveshaft or tyre, something specific to that one unit?

 

[highdesertrange]

yes it is specific to the engine. if you replace the flexplate the motor will no longer be balanced. how much of a difference this makes depends on the 2 flexplates. basically you don't have a choice here. you can't pull your engine apart every time you replace a flexplate and have it balanced. well I guess you could but it's not very practical. highdesertranger