goatwgn

Was kind of wondering "what if"? today on the Oldsmobile 403 engine. Everyone knows it came out as a "smog motor" in the 77' model year to replace the bigger 455 that was in the larger "B" and "C" cars the previous year. What if it had came out in 1968 with ram air, free flowing heads (perhaps off a bbo) a high rise aluminum intake, W-31 cam with 3.90 gears in a post coupe F85 or Cutlass, with a 4 speed? Of coarse it would have had a stronger block (like the solid web 350 from 68-76). And the rpm potential would have been great with the very large bore and short stroke. I have seen a few very good running 350 sbo in cars such as this (some even beating big blocks) and always wondered what they would run like with the .3 inch larger bore of the 403, with big valves.

captjim

http://72.22.90.30/phpBB2/viewtopic.php?t=36505

There is a flaw in your plan, though. You can't have everything, if you make the bores that big but keep the spacing the same (which you would need to do unless new heads were built) you still end up with flimsy, Siamesed cylinders. And heavy pistons.

IMO, the solid webbed 350 is a good performance platform. Good bore/stroke and rod/stroke ratios, solid block, decent crank. Add aftermarket pistons and rods and you have a strong bottom end reasonably priced. The shortfall of the 350 in stock form are the heads, but that can be remedied easily enough.

goatwgn

You are right. The 330 has good performance as well. Forgot about the siamesed cylinders. I did a performance build on a 68 350 about 9 years ago, and have it in dry storage. Dont have the heart,or the time right now, to remove the 480,000 mile 350 (that still runs very well) out of my 74 Cutlass Supreme.