What different sp converters came from the factory? Do the all interchange? How much variation in stall speed? Thanks!
Large units, from SP400 are 1800-2600 and smaller ones from SP300 are the same. Smaller units, 12" vs SP400 13", were found on 300 and V6 engines.
The larger 13" stock units had maybe 2100 high stall, and 1100 low stall. I had one of these units, and low stall was unusable to me. I now have a 12" TSP prepped converter with 3200/1800, and I love it. My low stall now feels like the high stall of the 13" converter. The 12" units came stock behind the small blocks with the ST300 trans.
I also run the smaller ST300 vp converter in my ST400 and love it. The only mods were to mill the stator piston for max high stall travel, spot weld the fins and install new Torrington thrust bearings. I'm getting over 3000 rpm at high stall and love the stock low stall for cruising. I kept the original closed throttle microswitch in place so that at idle it sits in high stall to survive the TA 308S cam. Devon
They made three SP converters. The 13" for all the big cars (ST400 trans) was called a GM-4. And two types of 12" converters with the ST300 trans, one for the 300/340 engined cars called a GM-2 and the other for the V-6 powered cars called a GM-1. Have had good luck with the GM-1 in typical street/mild strip car build-ups (12 sec.) And typically can get 3,000 rpm stall out of one. Dave
