mtthw

I have a 87 305 tpi 5 speed rod knocking I can get a fresh 350 30 over from a trusted friend cheap he was going to put into his big 20 some foot boat but ended up selling the boat and held on to the engine. Later on needed heads so the engine has no heads and been sitting in his shop. My question is will my heads fit and will the car run fine with the 305 heads or should I save up and buy the 350 heads. I plan to buy the block off him either way. Would also like to know exactly what all I will need to do the swap correct I know about the knock sensor and will need the ecm reprogramed but what else? I have found a good set of 24lb injectors would these be alright or will they be to big? Any other tips or anything would be great. Thanks alot

five7kid

iTrader: (14)

Welcome aboard thirdgen.org.

Most likely your heads will be fine on the 350 shortblock. With marine engines, things can get weird, so first verify it is the same type of engine as automobile engines.

Next find out what pistons it has. Unless they have some dish to them, the 305 heads with their smaller chambers will make compression too high for pump gas.

The cam is a critical piece of the package. TPI isn't happy with some performance cams, so find out what it has, or be prepared to put in a cam that you know will play well with TPI.

Finally, you need to know what era the 350 is from. Your '87 engine has roller lifters and a one-piece rear main seal. Although possible, this 350 most likely does not have those features, so swapping your cam & lifters over to it may not work. And, the flexplate on your 305 may not transfer over to the 350. Get the casting number off of the 350 block.

Oh, you probably won't need to get your ECM reprogrammed, at least not for it to run well. You may want to do that to get it running better than factory, but that doesn't mean it's a must-do.

mtthw

OK I found out that the engine is out of a 70's pickup. The pistons are whatever a factory engine would come with just 30 over. It's also a 4 bolt if that means anything. Well the 24lb injectors be fine? Also is there something I can do to make my flexplate work or do I have to buy a new one for the engine? Also what should I look for? Thanks for the help

five7kid

iTrader: (14)

A 70's pickup would have dished pistons, so the 305 heads would be a good match.

24 lb/hr injectors are probably more than you would ever use, but would be okay.

You will need to get a flywheel (sorry, I said "flexplate" earlier, but you did say you have a T5 - so, "flywheel") for the '83-'85 f-body V8 application. Don't tell them it's a 350, just say "305". It'll be the right part and you can reuse your 305 clutch and starter.

mtthw

What degree of cam should I use? Also is there anything else I may need besides for the knock sensor and flywheel? Will I have any problems with the exhaust will it all work? Don't have money for headers right now but do plan later on down the road. Also what's with all this smog stuff do I need it or can I scrap it. Looks like it would free up alot of room. But If I need it I will keep it on. Just want to make sure the car will run fine without it. Thanks

five7kid

iTrader: (14)

The problem with stock 3rd gen exhaust is the driver side manifold and the 70's dipstick tube try to occupy the same space at the same time. Careful bending of the tube has been done by members so that you have both exhaust and a dip stick. Headers solves the problem.

The engine will run fine but won't be street legal without the A.I.R. equipment (what you called "smog stuff"). Of course, the 70's 350 isn't legal, either.

Something like a Comp XE258 is a nice upgrade from a stock cam but still TPI-friendly. You might want to consider new valve springs and retainers for the 305 heads, though.

mtthw

Hey thank you very much. I will give this all a try thanks alot

smart7final

FiveSeven kid is right