Hello Hamb! Been a real long time since ive posted, i have a question that i have not been able to find an answer to: I have a neat 1958 GMC 270 that i want to adapt to a 1950’s Powerglide transmssion (cast iron) and i have been reading up on the weirdness of gmc stuff, 12v starters and different flywheels etc. Currently the engine has a flywheel (old manual transmission removed) with a 6 bolt pattern and i guess 168 teeth starter flange. My question is: was powerglide ever offered as an transmission behind the 270? And if yes, what flexplate do i need? I have no issues with modding and i know that i can redrill a sbc flexplate, but i thought i should ask before i go that route, Thanks! /Fred
There are flex plates available for the GMC bolt pattern. I'm not sure about the power glide. Sent from my XT1650 using The H.A.M.B. mobile app
Hi Fred, we drew one up in Cad and had one cut on a waterjet, then tig'd it to a chevy ring gear, after that had the whole shootin match balanced. We are using a th350 behind a 270 in one of our NW Vintage Dragsters. There is a thread in here about it, i think I posted pictures of it.
Late 235 & 261 Chevys used the same flywheel and bellhousing as the G.M.C. So it should bolt up to a 235 Powergilde. Make sure you have the 6 cylinder Powergilde not the V8, they are different.
As far as I know only Chevy and GMC 4 bolt flywheels will interchange. I have a Chevy truck flywheel for 10 3/4" clutch on my 4 bolt 270 GMC. I did see it mentioned once that Pontiac V8 6 bolt might be the same as GMC, I'm waiting for proof.
Probably 58 to 61. I really can't see spending the time, effort and money to hook any engine to a cast iron powerlglide though.
Thank you for all replys! Great info and knowledge as usual. Pontiac v8 pattern shall be investigated. Regarding the thought why bother with cast powerglide i can’t really say why, it has to do with the spirit of the car, / Fred
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