So, I’m in a bit of a pickle. Bought an old 60’s built hot rod with a 1960 Pontiac 389 that had been worked over. Unfortunately some water got into it, so I brought it to a machine shop. Guy said it was bore .060 over and was running TRW forged at around 13:1 compression. He said some of the bores were pitted, didn’t think he could bore anymore. I wanted to sleeve it, but he talked me into finding another engine. So I found another 389. Turned out to be a 1963 389. No one around here is into early Pontiac’s, and guys said the starter was the only big deal. I had the guy at the machine shop check the bellhousing before starting tear down- said they looked compatible. Now that the ‘63 engine is almost done, I’ve stumbled across the fact that the bell housing bolt pattern is different- lucky me. Does anyone know if they can be made to interchange? Only thing I’ve found is that there’s two bolts that are slightly different, not sure how different though? The engine from the car was using a cast iron bellhousing for an automatic, mated with a Trans Dapt GC-25 adapter hooked to a Chevy T-10. Am I screwed??
@Rocky @pontman @55chieftain @flamedabone @Jeff Walker @draggin'GTO @applekrate @ROADSTER1927 @Elcohaulic @wheeltramp brian If not discussion, some of these guys may have some parts available or numbers needed. Love Poncho' engines !
Yes that is an option…. But then I run into another issue, Pontiac mounted all their manual trans at like a 15 degree angle. My shifter linkages will never clear the crossmember. Really should have sleeved the ‘60 block… That still may happen ☹️ Thank you for tagging the experts!
To solve your problems you might try to locate an aftermarket stamped-steel bellhousing. Best of luck on your project.
If the bolts are far enough off maybe you could get one of those BOP to Chevy trans adapter plates and drill a couple of new holes as needed. If the bolts are real close together could you enlarge the holes that are off and weld or braze a piece in there and re-drill it to the needed bolt pattern?
I haven’t had much luck locating one, but I’ll keep searching. I’m hoping it’s that simple, but my gut tells me it won’t be… I don’t have the 63 engine back yet to dry fit the cast iron bellhousing piece. Hoping someone on here has tried
You could also jump on the Ames Performance site ( cool links...then Pontiac forums) It's an all Pontiac site and there's tons of info / help you can get there. This issue has been discussed on there many times.
I wouldn’t do much until you get your block back and get a chance to try fitting your bellhousing to it. If the dowel pins fit and it is aligned with the crank, you may be able to elongate some holes or make a template for a thin adapter plate and have it laser cut (like the BOP to Chevy and vise versa adapters).
Thanks for the link, definitely helpful but can’t find much for the 59-60 patterns Thank you for the link. I will give him a call tomorrow Thank you for the suggestion, turns out they’re only about hour and a half away from me. The forum has been helpful, but pretty much seems like the two won’t mix. Also learned that the ‘61 + block castings are 1/4” deeper then the 60. I’ve noticed that Quick Time housing, but that seems odd… I think their housing is BOP style, which won’t fit my style. Yes, you’re right my hands are tied until I get it back. Was hoping someone here had done it or had another option. I think my best option may be to find an old scattershield for a 61-63 bolt pattern. It looks like a couple companies may have made them….. Anyone have one hiding?? Shoot me a message or call 603-454-5656
55-60 Pontiac bell patterns are different from 61-64 patterns. the 61-64 patterns were the early versions of BOP. But the starters would bolt to the bell housing. 64 blocks did have either bosses or tapped holes for block mount starters. So, the big problem for 61-63 engines were trying to mount a BOP type transmission (TH350/400) and have a way of mounting a starter. Stick shifts would still have the starter mounted to the bell housing, but trying to find one of those bell housings is few and far between. The 55-60 bell housing only have the top two mounting bolts that are common to the later blocks. The rest of the mounting bolts and the dowels are way different. I have had to draw up an adapter to put an early Pontiac 4 speed hydramatic to a BOP Buick 225 V6. It is not a fun conversion, but the Buick has a block mount starter, so I am using a Buick flexplate (for starting the engine), then a crankshaft spacer that will adapt the Buick crank flange to the hydramatic flywheel. Put it in perspective, I would get with Wilcap and see what they recommend. Good luck
61 to 63 same pattern as newer stuff just no starter mount on block. There is a starter plate that can be bought from Butler performance. Says for auto trans only though. https://butlerperformance.com/i-244...r-on-1964-and-earlier-blocks-bpi-p010004.html
You should have sonic tested the block before you gave up on it, those early 389s had some thick cylinder walls
Thank you for the info, that was a huge help. Man Pontiac stuff can get a little confusing! Thanks for the advice! Yes. Definitely should have sonic tested. I was perfectly fine with sleeving, even if it was all 8. Machine shop just kept talking me out of it, kept saying it would be too expensive. This snafu has cost me more in the end. Not sure why he threw such a fit about it. Won’t use this guy again. The good news I think I’ve found a solution! Had to think outside the box, but managed to find an NOS Offenhauser 5306 adapter; 61-64 Pontiac to Ford Flathead for $75, then a Speedway adapter from Flathead to GM. Got lucky, but what a pain.
I think Pontiac also had two different flywheels for these engines. You need to post some pictures of the housing and the block(s) to show the difference. May help someone later on. One of the problems you may encounter is a difference in the distance from the block to the ring gear when the flywheel is mounted. I don't know if thats the case with Pontiacs or not, but I know other engines that use the BOP pattern housing do vary. Thats important because it could affect what starter is usable. There was a thread on here some time back where a fellow discussed the problems he encountered when changing starters on a Pontiac. Hope you don't plan to use those 13:1 pistons on the street.
The Pontiac Paradise article on 61-68 bell housings was definitely interesting. I am guessing that the 15 degree tilt is to clear the floorboards on models that could also have the Roto 10 hydramatic. Also known as "slim jims", the Roto equipped cars had lesser of transmission hump. Reasoning here is that back in 1954, Oldsmobile ( & 1955 Pontiac) used a "slant pan" hydramatic for floor clearance, and that the 15 degree tilt is very similar.
The Jalopy Journal
