OffspringPhreak

Ok, I have a '90 Iroc with a stock 305 TPI. The engine has been giving me trouble for a long time(beautiful car, sadly the engine shows all the wear and tear). It's got a collapsed lifter along with a lot of other internal problems(it's been parked since a little after New Years).

I don't have the time(or place) to rebuild it, and was wondering what it would take to drop a 350 TPI in it(I already searched the rest of the forums and found out some pretty interesting stuff, like having to put in a knock sensor in etc etc, but I'm wondering if anyone has anymore ideas/advice).

Something like that wouldn't be too expensive wouldn't it(the figure I'm coming up with is 3-4 grand for all the modifications and the engine itself).

The reason I ask is because I've heard that the 350 can get a lot more power than the 305, and figure, why the hell not?

From anyone's experience, is it really that hard to get a 305 to put out more power? If so, how?

I'm kinda caught in the middle of what to do, there's a chance that I might be able to rebuild the 305(but I want to add more power to it), or just getting a 350 TPI and having more power to begin with and then adding power in the future.

I appreciate the help.

five7kid

iTrader: (14)

Certainly the least expensive option would be to fix the valvetrain. New lifter(s), pushrods, and valve springs would probably do it, unless the lifter roller is actually damaged in which case you'll probably need a new cam (and perhaps to disassemble the engine to clean out metal pieces from all of the passages & recesses).

The 350 is typically a good idea as long as you keep it close to factory - i.e., no old-school 882 heads, factory-type roller hydraulic lifter cam, etc. Here's a decent source for such an engine (my brother bought this engine for his '93 1500 PU) 1987-1992 CHEVY 350 / 5.7 ENGINE - CHEVY ENGINES 87-92 , specify 083 casting heads. Don't forget to add the shipping, core, and forklift fees to the price.

Since '91 TPI was the speed density system, you'll need to update the PROM in addition to the knock sensor stuff. Either get a factory 350 PROM, or get into PROM tuning.

Finally, which exhaust do you have? Single, or dual cat? If single 2-1/4" cat, you've got to get rid of that system and go either with a 3" system (starting at the y-pipe - not technically emissions-legal) or convert to dual cats.

4 grand should do it. . .

OffspringPhreak

4 grand? Ouch that hurts lol.

Thanks for the link/advice. I'm still trying to decide what to do(I figure that the money I pour into it will be worth it since I never plan on getting rid of the car, well, if nothing bad happens to it that is.).

It's a single cat exhaust(I've been planning on doing something with that for a while now.).

Either way I choose to take care of it it'll be a while, just wanted to get a basic gist of it. Thanks again I really appreciate the input.

five7kid

iTrader: (14)

Remember, that was your number. . .

OffspringPhreak

Yeah good point, I was just hoping it would've been less.

MikeC.86Roc

iTrader: (10)

If you want more bang for the buck, I would go for the 350 swap. It is possible to make more power with the 305 of course, and lots of guys here have done it, but having a 350 under the hood is more fun in my opinion. Seems like there are more options out there for future upgrades as well.

If you have a local junkyard, they may even have an early 90's truck motor with 4 bolt mains and the roller lifter bosses in the block. That's what I found for my Iroc and did the 305 to 350 swap. It was a fun project.