Engine swap questions.

[Clod_King]

So I just purchased an 86' GMC C20. They guy is gonna pull the engine, and exhaust, and deliver the rest to my house no charge.

The donor engine is from my 89 suburban. The burb has a TBI 350, mated to a 700R4 transmission.

I have a few questions...

The C20 is going to be delivered with the 2WD TH350 under the truck. Will my torque converter, and flex plate mate up to that tranny?

Will my computer start throwing error codes, or make the engine run poorly if it is not hooked up to the TH350?

Will an 86' TH350 have a wire harness? Or is that a tranny that operates on it's own.

Would it be easier to find a 2WD 700R4, and use that. Or can I convert my 4WD 700R4 to a 2WD unit?

I haven't done an engine swap before, and I definately haven't gone from carb to FI, but I have done alot research, and these are the questions I have left...

 

[76zimmer]

The flexplate should work fine, but I don't think the convertor will. I don't believe the computer controls anything on the trans that year, as its a 700, not a 4L60E. The 350 should be able to be run without any electrical hookup.

 

[Clod_King]

So I'll need to buy a torque converter then...

One more question. What does it mean when a torque converter has a 3000 rpm stall?

 

[76zimmer]

probably not to good to use on the street or trail....it will move the vehicle, but you may have to rev a little more than a normal stall (12-1400) convertor. It will generate a little more heat also. Hi-stall convertors are made to allow the engine, under full throttle to rev more to the peak power band before engaging fully.

 

[dyeager535]

You need to figure out first if it's a TH350 (lockup converter TH350) and if it is, then you need to find out if the TH350C and 700R4 converters are interchangeable. I can't answer that, but I'd WAG yes. Someplace like Summit would probably prove it, with matching part numbers for both, or disprove with different part numbers.

 

[76zimmer]

You need to figure out first if it's a TH350 (lockup converter TH350) and if it is, then you need to find out if the TH350C and 700R4 converters are interchangeable. I can't answer that, but I'd WAG yes. Someplace like Summit would probably prove it, with matching part numbers for both, or disprove with different part numbers.

Dorian, I looked those up, and they list different convertors for each type trans. T350,375,400,425 are the same, and 700,4L60 are the same.

 

[dyeager535]

Did you look up the TH350*C* though?

It's fairly uncommon with the aftermarket from what I've seen, but even if I looked them up in the GM parts manual, I'd have a real hard time figuring out if any of the converters shared the same part number, because GM used so many different converters each year, even on the same transmission. Just looked it up, the TH350C is easy, They were only offered with the 305 in these trucks, and there was only one converter. It does not interchange with the 700, nor does the input shaft itself.

 

[Clod_King]

Thanks for the run down on what the "stall" is.

Okay, so the torque converter for my 700R4 will not mate to the TH350.

But can I use my 700R4 flex plate with a torque converter for a TH350?