After an extended timeout, I'm finally ready to drop my engine and trans back in. Naturally a few miscellaneous bits have vanished in the meantime. Nothing major (knock wood), but I can't find the trans to block bolts, and I'd rather be sure on the size.

Anyone know the length of the six bolts? 425, TH400. TIA.

 

 

I've used closer to 2" grade 8 bolts. Use hardened washers. I'm not familiar with the 425 block but the others use all open holes with lots of space so you can use long bolts.

 

All Olds engines use the same size bolts to mount the trans or bell housing to the block.

 

No, they don't. Five of the six holes are through holes. The one near the oil filter adapter is a blind hole on all 1964-1990 Olds blocks.

 

Can I jump in on this thread ? Same topic - different bolts. I have a 1965 F-85 wagon that someone put a chev 305 in with welded mounts. All of that is now removed and I'm installing an Olds 350. I have the frame pads - what size bolts do I need ?

 

 

You forgot the phillips screwdriver :-) Thank you for the reply. Frame pads are in and its looking like an Oldsmobile again. Sorry for hijacking the thread. I simply couldn't think of a better subject line to ask my question. Oh ya. 1" is the perfect length.