I have a 1986 Iroc-Z with MAF style TPI 305 engine. It has 148,000 miles. It leaks and burns oil at a rate of 1qt/100 miles. I urgently need to do something about it. Amazingly, it stilll feels powerful and I can have a lot of fun with it. Its only mods are a pair of Hooker headers and catback, no cat, and a descreened MAF. This is my daily driver so I need something reliable and cheap and that will yield good mileage. Remeber, I need cheap because I married recently, and besides I have a 67 Camaro (still unrestored) that I would rather pour my money into.

I have three options right now:

Option 1
Rebuild the 305 that's in it. A cast piston kit from naparts.com is $313 w/ moly ring upgrade. This engine has a hydraulic cam.

Pros:
-No need to mix different parts from different engines
-No need to burn chips
-Good mileage.

Cons:
-Kit is about 40% more expensive than a 350 kit
-Less power than a cheaper 350 rebuild
-Cam is not roller, too expensive to retrofit.

Option 2
A friend can sell me a 350 engine from a 1978 burb for about $100 at most. It's running perfectly fine in the burb now, but he's going diesel. It doesn't need a rebuild. I read in other posts that it's better to swap my heads into this engine than to use the 78cc or so heads on the burb, so that's what I would do. Should I also swap the current cam in my 305 (with the corresponding lifters) into this engine as to not disturb the computer or should I keep the lazy cam in the 350 until I can afford a new kit? Can I get away with not buying higher rated injectors, just increase fuel pressure and not messing with burning chips for now?

Pros:
-Cost only about $50-$100 for the engine and $60 for fuel pressure regulator. Maybe $19.95 gasket set.
-More power than a 305
-Can upgrade cam later and make even more power;
-Rebuild kit cheaper than a 305 (and it doesn't even need it now)

Cons:
-Less mileage than a 305
-Engine is used
-My cam might be too worn down, add another $100 for new cam.
-My heads on that engine might not be the best combination.
-Might need injectors (add another $230)
-Might need to burn new chips (add another $200 for the equipment needed)

Option 3
Rebuild a 1988 TBI 305 w/ roller cam that a friend will give me for free. This engine was rebuilt just about 5,000 miles ago, but it started overheating so he's building a 350 to replace it. I'm almost sure it was a bad shop job. I will swap the TPI to this engine. The kit for this engine is $494. f I choose this option, should I use his heads or mine?

Pros
-Roller cam
-Good mileage
-More power than the current 305 thanks to cam
-No need to burn chips

Cons
-Engine kit way too expensive
-Less power than a 350

Thank you for taking your time reading this. Any help greatly appreciated. And remember I'm in Guatemala, Central America, so everything mentioned here has to be shipped and pays taxes, increasing my costs.

 

Your rebuilt 305 heads on the 350, with a new flat-tappet computer-compatible cam sounds like the ticket to me. Adjustable fuel pressure reg will allow the 305 injectors to work with the 350. The MAF will handle the increased displacement with no problem. Wouldn't surprise me if your gas mileage actually increased. You will need a two-piece rear main seal type flex plate, though. The dipstick will be on the other side of the engine, but you have headers so that won't be a problem.

I wouldn't spend any money rebuilding a 305 lower end, personally.

 

IMO go with the 350, but you'll be mixing and matching some parts. the '86 305 has a one piece rear main seal, whereas the '78 has a 2 piece rear main seal. This means you'll have to get a 168 tooth, internally balanced flexplate and a starter to match in order to make it work. If you have that '67 camaro you want to fix up, then stick with the less expensive engine swap. As for the 305 19pph injectors, they will power the 350, but it will be running on the lean side. Hope that helps you some.


edit: didn't see five7kid had already said this sorry

 

If you get a 153-tooth flexplate, such as used on '83-'85 3rd gen auto, you can use the same starter. The block should be drilled for that starter bolt pattern.

 

I have a 78 350 from a blazer. i just have a 204/214 cam and headers, edelbrock intake and 600 carb. i say just put the 350 in the car as is, forget the TPI and the F ing computer. My car kills my friends 86 TA carbed 305 5 speed. So that motor should make your car faster than before. Plus 350 carbed motor is cheaper to build.

 

Thanks for your replies!

I was also thinking that the 350 option was the best, but I didn't know there were differences in the starter mounting holes. What if I use the 168 tooth (I think) flexplate and starter from the donor burb? Any problems matching that to my TH700R4?

We opened up that engine (needs gaskets anyway) and discovered that it has flat top pistons with valve reliefs. If I use my 305 heads, I would end up with more than 10.5:1 cr, right? I think this would be too much for a daily driver. The heads on the 350 I believe are 78cc since this burb was rated at 8.5:1 cr, which I think it would be too low, and I don't want to spend money in milling them, besides, those are inneficient smog heads, if I'm not mistaken.

Should I go with the 78ccs? or should I go junkyard hunting and try to find some used heads which only need a valve job? I'd love to find some vortecs, but I can't afford the new intake base for the TPI.

Junkyards around here have heads classified by the car they were taken from. From which cars should I look for?

Thanks again for your help.