I have a question for some people that may have had real world experience with this. I have a 1966 Pontiac Tempest Custom wagon that has a '73 455 with 9.5 to 1 compression, 4X heads with 1.77 exhaust valves installed, a Hughes GM 25 convertor in front of a TH400, with a Gear Vendors overdrive, and a 3.42 rear with 27.4 inch tires. It presently has an 041 (Melling) cam that I am changing out in a couple of months to improve my idling and low speed driveabilty with the AC, and the fact this is more of a cruiser and not a race car. I am going with a Comp Cams dual energy 275 deh grind. It states I can use a "stock convertor" with this combo, and my engine builder ( a very nice fellow on this site) has also informed me I can go with the stock type convertor, being I am looking for a nice tight convertor on the highway with my GV unit, but at the same time I like the power of the 455.
The question I have for you all is have any of you used the Hughes GM 20 convertor in a combo similar to this? Hughes states I can still use the GM25,(and it has been good with this present setup), but if the 20 would work better, I would prefer to do that while I have the engine out. (The "Contenental" convertors sound nice, but are a little beyond my present budget) Taking engine out to do the cam,for some underhood detailing as well. Will be easy to change the convertor while it is out.Thanks for any input.