So I am swaping my 216 for a 250 in my 51 Styleline and got some good help from you HAMB guys who have done this before and even got turned on to a Weiand adapter plate for the trans which was for sale by another member. So I bought it and figured out real quick that it is not a bell housing to block adapter but a belhousing to trans adapter. That's cool because it probably is exactly what I need, but what I don't know is what bellhousing I should run. I was told before that I could adapt a #421 (3788421 as I found after full clarification) to the trans with some modification, given part #s for a throw out bearing, and even given the right flywheel specs. The question now is what parts do I use with my adapter plate????
Without more info, I can tell you this; The early sticks look a lot like the later ones where they bolt to the bellhousing. Maybe the bolt pattern is different, but also the length of the input shaft must be checked. Seems to me that an adapter might space the trans out and make the input shaft not reach the pilot bearing. Get your bellhousing, bolt it up to the block, and try the trans to it. Any mismatch will be apparent.
It would seem, using any stock bellhousing, and adapting it to a stock transmission, that a bell-to-trans adapter would compromise the input shaft seating into the pilot bushing/bearing, and to a lesser degree, the input splines and throughout bearing. My old Speed Gems adapter bolts to the 51' trans, the adapter then bolts to a cast iron Powerglide starter ring, uses the 14", 168 tooth flywheel, the 3 bolt cast iron starter motor that bolts to the Powerglide starter ring, the 51' disc, and a 10.4 pressure plate. I plan on going to the later style six also, although the Speed Gems adapter was originally made for a V-8 conversion. And, I paid $25.00 for the Speed Gems adapter off that auction site we all know and love! Butch/56sedandelivery.
The input shaft length on the stock trans seems to be a little longer (about 3/4") than the input shaft on the rock crusher that I took a bell housing off of.
So, if I understand right, you went from a 216 to a 250 six, right? The 250 uses the generic GM Chevy bellhousing bolt pattern. Same as the V8s. In other words, might be time to upgrade to an automatic or a 5 speed manual tranny. Just something to think about..................
I can post the pic as soon as I get the adapter back. I left it in a mill at the machine shop so I could duplicate it just in case I have any problems. I do have a 4spd trans and bell housing now that came out of a 63 truck with a 250 in it (not the original engine I don't think) but don't have the $$$ for a rear and driveshaft yet. I am also working on a turbo setup for my 250 so the stock drive line will likely not last long but I am going to try. Blowing up the stock stuff gives me an excuse to try to build a better driveline faster. The unfortunate consequence of my endevor is that most likely I have to choose between my beloved 3 on the tree and the ability to be different and run a turbo, and I have to choose the turbo because.....I can and I have not seen it done in person yet (I know it has been done many times, just not around here that I know of).
It's been a long time but IIRC, all the gears from the car case will fit a pickup (49-54). And that cas bolts up to the 250s stock housing. There may be a small difference in overall case length, but not much. Anyway, try a pickup trans, I think it will work for you. But, you will have to fab rear mounts as the stocker mounts on the housing and the 250 is intended to mount from the trans. Not really hard to do, just cut/drill a plate to bolt to the trans tail housing bolts(at least 2 preferably 3) and accept a rear mount.
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