TH350 Torque Converter.

[paulrowe]

Hi Everyone! I'm looking for some torque converter advise. I have a 1979 K10 with a TH350. The previous owner put a super lumpy cam and a high stall converter for some unknown reason. Anyway the truck is a dog starting off. I just bought a Comp Xtreme 4x4 cam which is good for 600 to 4600rpm. I'm wondering if a stock Gm rebuilt converter for $130 is a good route to go? Or do you have any recommendations. I just want to tow 5000lbs and do some light off roading. Thanks any help would be appreciated.

 

[Honky Kong jr]

Hi Everyone! I'm looking for some torque converter advise. I have a 1979 K10 with a TH350. The previous owner put a super lumpy cam and a high stall converter for some unknown reason. Anyway the truck is a dog starting off. I just bought a Comp Xtreme 4x4 cam which is good for 600 to 4600rpm. I'm wondering if a stock Gm rebuilt converter for $130 is a good route to go? Or do you have any recommendations. I just want to tow 5000lbs and do some light off roading. Thanks any help would be appreciated.

That should be fine. Just add an external trans cooler run in series with the one in the radiator.

 

[74 Shortbed]

I would get one that has Torrington bearings and furnace brazed turbine for towing, you'll never have to worry about it..

 

[paulrowe]

Ok thanks guys. What's the best stall converter to purchase if I bought a new converter? Is 1600 to 2000 what I want? Or would lower be better?

 

[75gmck25]

High stall converters are usually 2500-3000 rpm, and your stock converter was probably closer to 1000. However, that high stall converter should help you off the line, not make it run like dog.

Since you don't know the current stall speed, I would just swap the cam for now and see how it runs. With a decent cam to bring back your low end torque, the truck may wake up quite a bit. Those lumpy racer cams sound "bad" at idle, but only develop power at high rpm with good flowing heads. They usually suck in an otherwise stock SBC in a heavy vehicle.

Also make sure you have plenty of initial timing, and that the full mechanical advance is coming in by about 2500 rpm. I would start out with 12 degrees initial, and try to get 20 degrees more mechanical by 2500 rpm (32 total). You might even get by with 16 degrees initial, but may have trouble with pinging when the vacuum advance comes in during part throttle cruise.

Also remember how much of a PIA it is to swap that torque converter. You need to either pull the engine, or pull the trans/T-case combo. Neither one is much fun.

Bruce

 

[paulrowe]

Thanks for the advise Bruce. I'll try that first then and see how it runs. I'm not sure what stall the converter is now, all I know is it's painted green and not stock. Also i have 3:08 gears and 33 inch tires. I know that's not helping so I'm swapping to 4:11 soon.

 

[75gmck25]

Swapping in 4.10s would really help you get off the line.

4.10 was a very common gear ratio for the 73-80 3/4 tons, and was a fairly common option on the later 3/4 tons. It would probably be easiest to just swap both axles, if you can find a donor truck. I would also take a close look at both sets of driveshafts, just to make sure you have the right yoke on each end of the donor axles.

Bruce