Rebuilding my current ‘68 350 SBB with reliability and a step up in performance in mind. Current crankshaft is worn out(already ground down and just lost a rod bearing). I have a ‘73 to use for parts. Any differences in cranks? Thanks
Hi, the only difference is the weight of the counterbalance. Any machine shop can re balance it for you though.
@sean Buick 76 Are you aware of any differences in the blocks? Would it make more sense to freshen up the ‘73?
Yes there is one advantage to the 73 block, it has a larger oil pickup passage. I’m Not convinced that is any real advantage but it’s physically larger. The main thing is your cylinder head pick. The 73 block can use any year head. The 68 block Is only for 68-72 heads. I would use which ever block is in the best shape.
Sean, does the 350 blocks have such difference in thickness like our BB? Or do they sonic pretty close to each other. I’ve never done a SB but I assume they would be no consistency like the BB. Fernando
i sonic tested 8 blocks to pick the best one and yes there are wildly different thicknesses. In general the 68-70 blocks have thicker walls however they still have core shift issues. The later blocks are still core shift prone. In general it’s a crapshoot, and my philosophy is to just pick a good running engine and bore it 30 thou without checking the sonic test. I don’t see much point in spending a bunch of time and money to see if an engine can go 60 thou overbore vs spending that time on head porting. I spent the time and money checking & blocks to find the best one as I was planning to shoot for 800+ Hp. That engine has since been slated for a 13:1 NA engine that will likely barely break 500 Hp.... I’ve since built a new turbo 350 engine that was sonic tested, bored 30 over, girdle, billet crank etc. So yes core shift is a big issue, but I wouldn’t even sonic test unless using a power adder, revving over 6500, or trying to bore over 30 over.
Thanks, the '68 block is definitely in better shape. Going to give it a bath and double check everything is still flat. It was bored and decked 5 or so years ago, still looks to be in good shape. The '73 has never been apart. What is the difference with the heads? I was looking into TA's stage1 heads for it, wondering if there would be an added benefit with the '73 block and those heads vs '68.
No appreciative performance difference in the heads for performance. I plan on flow bench testing all the year heads to have proof, but I haven’t done it yet. I have all the year Heads on the shelf to test. the alum heads are great, however I feel that custom forged pistons and forged rods are needed to make the most of them. $ for dollar I see larger HP potential by optimizing the compression ratio, cam pick, and quick clean up porting on the iron heads.