I want to Rebuild my 305 only using the Block from the old engine. This is my first rebuild and I was wondering if anyone had any tips or suggestions

 

Not sure exactly what you mean by "only using the block from the old engine". Does that mean you're throwing away the heads, intake, carb/TBI/TPI, exhaust manifolds, cam, lifters, rockers, crank, rods, pistons, flex plate, harmonic damper, oil pan, timing cover...

I think what you mean is you're keeping the shortblock but would consider changing heads, cam, intake, etc.

It would help to know exactly what you have now, such as year, induction type, transmission, modifications so far, intended use, emissions testing or not, etc.

Basically, the typical rebuild involves disassembling the engine, taking the block, crank, rods & pistons to a machine shop, having them remove the cam bearings and casting plugs and "tank" the block to clean it inside & out, bore the cylinders something like .030" over to match new oversize pistons, installing new cam bearings & casting plugs, grinding the crank .010" under (or more if necessary), re-sizing the rod big ends (optional), installing the new pistons on the rods, and giving it all back to you for assembly. Or, pay them even more and they'll assemble it for you.

A good 305 upgrade is the World Products S/R Torquer 305 heads, which have larger intake valves, improved combustion chamber shape, improved port flow, use screw-in rocker studs, and can tolerate more valve lift. You can get them for ~$650-700 assembled, or get them unassembled and have them "pocket ported" (or do it yourself if you're up to it) for even better performance.

If you don't want to replace the heads, give them to the machine shop at the same time as the block and they'll do a "valve job", check for cracks, etc. If you decide to go with bigger intake valves, machine them for screw-in studs, and have them pocket ported, you're looking at close to the same money as getting the new World pieces.

Cam selection will depend upon what you've got. Ditto for induction improvements.

That's a start. Give us some more info and more specifics can be given.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
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Sorry about that allow me to clarify.

I have an 1985 Trans Am. The engine is a 5.0 liter V8 TPI, Fuel Injected, Automatic Tranny. It is all stock. I intend on disassembling it and improving it to get max performance.

 

Your 305 shortblock is actually a pretty stout piece as-is. I'd suggest you upgrade the rod bolts and have the rods resized, and retain the stock cast aluminum pistons. I'd replace the oil pump, and perhaps have the reciprocating assembly balanced and the block line-bored. Other than that, I wouldnt do anything more to that block, beyond the standard rebuild stuff like a cylinder hone & new rings. If you need to re-bore and buy new pistons, then I think the expense warrants looking for an extra 45 cubic inches, if you know what I mean. Your rebuild costs will be identical, except for the cost of purchasing a different shortblock (typ. $250 or less)

As to the remaining parts of the engine, I totally concur with five7Kid's choice of heads. Invest your money in the valvetrain. The 305 shortblock is good to 400 HP as-is, assuming you upgrade the rod bolts.

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Daniel Burk
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Daniel,
What rod bolts would you recommend? I'm about to take the pan off my LB9, don't plan on disassembling the whole thing (pan's coming off for cam change & new oil pump), but I should be able to replace rod bolts without removing the pistons. Now would be the time to do it.