AnthonyZ28

I possibly blew some piston rings a few nights ago in my 1991 305 tpi lb9 and I'm trying to decide if I should rebuild the 305 with some flat top Pistons or try to find a 350 short block to put it.

I can get all of the stuff to rebuild it(bearings, gaskets, timing chain, oil pump, and Pistons)for less than $300.

Or I could try to find a cheap 350 and maybe just use it as is or replace the bearings

My question is can I use my 305 prom on it or do I have to get a 350 one?

Why could you not just use the same cam and use the same 305 prom?

TTOP350

iTrader: (8)

What makes you thing the rings are gone? Have you done a compression test on the motor yet?

AnthonyZ28

Well it had 190k miles and I was spraying 125 shot of nitrous. Started smoking bad halfway down the drag strip from exhaust and the blow by blew tons of oil out of the dip stick. Every time that cylinder fires you can feel compression out of the oil feel cap.

TTOP350

iTrader: (8)

LoL, yup, that may be a good clue.

stephenscamaro

a 305 at the strip? I bet you catch a lot of flack. No offense~

AnthonyZ28

Most of the time they don't believe it lol. Runs 9.0 on motor in 1/8 and 14.1 in 1/4. And ran two 7.8s on spray and a 12.5. Can't remember if I let out or not usually runs out of gear at about 105

That's mainly why I'm not convinced to swap to a 350 when I can run just as fast

TTOP350

iTrader: (8)

I had a 305 that ran 13.90s with mods of course, wasn't a missle by any means but it was fun playing around with it back then.

sofakingdom

iTrader: (1)

Probably not "rings"; more likely, a hole in a piston; but yeah, the end result isn't too much different.

While a 350 might or might not be the best choice for a replacement, one thing is for sure: the right answer ISN'T a 305.

cosmick

I wouldn't waste money putting forged pistons in a 305, I'd fix my fuel system, get a nitrous controller, and run a 350. There are cast-piston 350s living with 300-shots. But if you decide to go forged, be aware that there are 2 different alloys of forged pistons, the cheap ones are 4032, IIRC, and the sreious ones are 2618, IIRC. The 2618 ones will eventually go plastic, and deform, to save the rest of the engine, this is what you want. The cheap ones are brittle, and if you hurt one, you'll end up having to replace the entire engine, heads and all. They're for street guys wanting to brag about forged pistons in their "500-horse" mild builds. Good pistons for a 305 are likely to run $600+, when you finally find them.

AnthonyZ28

Well I figure I can rebuild it with some flat top Pistons off of eBay for ~$115 and piece the rest of the parts together and possibly rebuild it for around $300. The only reason I'm thinking about the 350 is because I can get one and put it in for about the same cost as long as I don't have to fool with the computer.

I know it definitely isn't going to be the fasted but it's my daily driver right now and cheapest is best until I finish school and get a real job.

I do have future plans of ls swapping though.

cosmick

If you're serious about going LS, then get a salvage-yard 305, stop spraying it, and stop buying SBC upgrades that can't transfer over to the LS. LS swaps are costly enough even when you take every possible shortcut. If you can't afford a chip to go with a 350, then forget going LS. You wouldn't have this problem if you had corrected the fuel system before spraying.

dmccain

iTrader: (2)

Get the 350. You could re-use the cam if its in good shape because the TPI 305 and 350 shared the same cam in the last few years they were made. You could even use the 081 heads off the 305 in a pinch because they aren't bad heads.. The computer would run it but I would look into bigger injectors and a chip burn.

AnthonyZ28

I have 19lb ford injectors which were designed on a lower pressure than gm so they run a higher pressure than 19. I also have an adjustable fuel pressure regulator so I think the fueling would be adequate for a 350.

AnthonyZ28

I'll be able to afford it when the time comes and I don't know of a good place to get a chip made. I'd prefer someone make a custom tune for it.

I bought a chip from Custom Chips Inc.(which I believe is John Wayne) and it gave my car no more power. Ran the same time on the track, if not slower. So I don't really trust the mail order tune.

Metalizer

I'll tell you what everybody told me about investing money in a 305....don't waste a penny on it.

I pulled my 305 and now in the process of building a carb 383. Looks like total cost for the build is around 3k.....and that's me picking up a vortec 350 from the salvage yard for 400