Originally Posted by rollie715
I wonder if the 350's from the early 90's were basically the same shortblock, same compression ratio, roller lifters etc, so if I bought new vortec heads, I could just as easily put them on an early 90's block.
There were some slight differences in piston rings- some had deep and some had shallow oil rings, and some were metric. There were true FT pistons used on some Gen 2 SBC engines.
There were powdered metal and forged steel rods used on different engines during this time period. By '96 when the "good" Vortec heads were on the 5.7L L31 engines, all the rods were PM as far as I know. And all the pistons were dished, around 11-12cc.
To me there doesn't seem to be any real difference in the durability of forged vs. PM rods. Others will disagree w/this, preferring the old style forged rods over the PM rods. My thoughts are, if PM rods aren't good enough then it's time to move up to a better aftermarket rod, because the rod bolts have to be changed and the rods resized at a minimum anyway. For a couple dollars per rod more, you can have sized and ready tobe balanced rods w/better bolts, etc. in an aftermarket forging. If you are on a budget, use the stock rods, resized and w/new bolts, and call it good.
For me the ideal scenario would be to find a '96-up 5.7L Vortec long block in good shape for a good price. Add the induction system of your choice, from a carb to an aftermarket TBI EFI to whatever.
Another option you will hear is to find a good Gen 2 engine and run it w/the stock TPI set-up. The LT1 engines were never in large supply and are getting pretty long in the tooth, but if you can find a good one for the right price, it's an option that might work for you. Be sure you don't get the "baby" LT1.
There were TBI engines that used flat tappet cams, some of these blocks lack the bosses to use a factory roller valve train. This has been posted before, but not for a while, so:
350cid roller tappet blocks are casting numbers 10243880, 14011148, 14088526, and 14093638.
1986-up 350cid flat tappet (i.e. non-roller) blocks are casting number 10054727, 14079287, 14088548, and 14101148. These flat tappet blocks may have the provisions for a roller cam (i.e. bosses cast in and tapped for the spider, tapped holes for the cam plate, etc.)- but also may not
be so equipped- but these blocks will have a flat tappet cam and non-roller lifters, no spider, etc. These blocks are fine if you don't care about the roller cam.
There is a flat tappet block and a roller block that both end with the numbers 148. 14101148 is a flat tappet truck block, 14011148 is a roller provisioned block.
Some blocks came machined all the way for a mechanical fuel pump. Others have either partial or no machining done to use a mechanical F/P.
A member here posted this regarding the fuel pump (sorry, I don't recall the name to give proper credit):
"All of the 638's that I've seen (not that many, 5 or 6) have had the pump rod hole drilled. I've seen 880s both ways, and both 14011148 I've seen were undrilled."