Ok i have a 87 iroc z with a 305 tpi and am planning on swapping it for either a 350 or a 383. Now my main goals on this project are to gain some knowledge about motors (this is my first engine swap/build...im basically an engine noob), build a fairly fuel efficient car (20 mpg highway is my target but could live with less), get decent power (definitely want lots of torque but wouldnt mind some extra hp), and do it all with relative ease for under $5000. So i guess my first question would be can a build a reliable 350 or 383 as described above and which would be a better choice. Then if anyone has advice on where to start and how to get the project rolling, that would be great! Now i am doing this on my own so any and all advice would be greatly appreciated.

 

Welcome aboard thirdgen.org.

For starters, you've come to the right place. Just make sure what you hear makes sense and doesn't just sound good before you do it. . .

You'll have to do most of the same things whether 350 or 383. 383 will just cost you $600-1000 or so more. Also be aware that TPI limits a 305 in some respects, so putting it on a 383 will just exacerbate those issues. And, if fuel economy is a major player in the equation, then 383 makes even less sense.

#1 has got to be exhaust. If you don't replace the stock exhaust manifolds with headers and the factory cat with an aftermarket high-flow unit, nothing else you do will have the desired effects. I'd recommend Hooker 2055HKR, or (especially if going with 383), get in touch with member Dyno Don about the headers he makes. Most any direct-fit 3" cat will be high flow (like Catco 9118).

How much of the engine work do you want to do? I'd certainly recommend starting with a roller lifter block ('87-up). If you build from there, decide if you want stock factory heads (you could even use your 305 heads with some improvements), or aftermarket. Cam choice should be compatible with the TPI computer (many choices available). Pistons should be chosen after you know what heads you'll use so you can get the proper compression ratio.

The TPI will need some improvements if you want to spin over 4500 RPMs. The Holley Stealth Ram is probably the least expensive way to handle most of them. You should also get 22 lb injectors for 350, 24 lb for 383.

You'll need a 350 knock sensor.

There are other details that are needed if you don't have any engine building experience, but most of those can be found in a decent shop manual.

 

Thank you! I was doing some research and came across this site pretty quickly...AND

 

DID I STRIKE GOLD!! i really would like to do as much of the work as possible that doesnt require major machine work. In regards to the block, should i just buy a block and buy new parts or buy an old 350 and use some of the internal components? And also can i buy the moving components before i decide on the heads and cam? I definitely want aftermarket heads, cam and intake...i think? shouldnt that be where i put most of my money? And my main question rite now, carb or FI. Ive heard that the stealth ram is the way to go, but how big of a change is it and does it hurt my fuel economy that much? Do i have to do any computer work in the car if i switch? Im sorry for all the questions but im really interested in this project and want to get started!!! Thanks agen

 

Decide on heads first. You need to know your chamber size before buying pistons. And, you need to know if your cylinders will need to be bored to the next oversize before ordering pistons.

You can get a used 350 and reuse some of the internal components, such as crank and rods. You should figure machine work will be required. This typically includes hot-tanking the block (a cleaning process - performed after removing cam bearings, freeze and galley plugs), boring, cam bearing installation, and galley/freeze plugs installation. The machine shop should be willing to check out the block for you and tell you what size pistons to order. They will want the pistons to check the final bore size of the block. They will probably charge more to have the pistons pressed onto the rods, but this is something you should expect to have them do. With a few basic tools like ring compressor and torque wrench, you should be able to do the rest of the assembly yourself if you have a clean place to work on it.

I wouldn't say aftermarket heads are a "must". "Good", perhaps, but the right factory heads properly prepared will easily support a TPI 350.

I wouldn't go carb, especially if fuel economy is in your equation. I'm not sure how much, if any, the Stealth Ram will affect economy. Check on the TPI forum.

The '87 system is MAF, and won't require any reprogramming to run. To get the most out of it, though, you might want to either get an L98 PROM ('87-'88), or get the equipment and learn how to reprogram yourself.

 

When i am choosing heads, do i need to have the heads machined to the blocks specs, or do i have the block machined to heads specs? For example if i choose vortec heads, ikno they have limited lift, so which would i have altered, head or block? and other than vortec heads, what are other quality heads that work with my engine?

 

The valve lift limit of Vortec heads has to do with the springs and size of the top of the valve guides. To "fix" that, you need to modify the heads - have the guides cut so you can fit better springs and increase the travel of the valve before the retainer hits the top of the guide.

Vortec heads require a Vortec-specific intake manifold (in the case of TPI, Vortec-specific base). Other than that, they are a fine choice.

Other choices include your already mentioned 305 heads after machine work to install 1.94" intake valves (and 1.60" exhaust valves if you wish), and basic port clean-up work, along with new valve springs. Or, L98 heads, aka 083 castings. Sportsman S/R Torquers; Summit has some stock replacement type heads with their name on them; aluminum Vette L98 heads (113 castings), the list goes on. Basically something with ~64cc chambers (58cc fine if aluminum or dished pistons) and 165-170 cc intake ports.