Got an '87 Chevy 3/4-ton, stock everything and the TBI EFI system. I'm considering the GM crate motor P/N 12497317 (crate 383) to replace the truck's dead/quickly dying 350. It's cam is P/N 14097395 w/ spec's .431"/.451", duration @ .050 196/206.

Can anyone comment on if the stock EFI will work with this engine unmodified, and if not what modifications are needed? (Fuel pressure? Injector size? Chip?) Just looking for a quick, good replacement motor for the truck (with some more power while I'm at it) and this engine is looking like a very good candidate.

--Rob

Try Turbo City website

It's being rebuilt...and I'd like to work with the stock Chevy EFI rather than switch to an aftermarket set-up if at all possible.

--Rob

Here is the spec sheet on the 383 you are thinking of. GM recommends using a Q-jet or 750 Holley. I have also read about there being a 383 TBI crate engine coming out soon but it is not listed on the GM performance parts website.
http://www.gmgoodwrench.com/perfparts/images/parts/pdf/12497317.pdf


I found this TBI 383 and it's specs are very similar to the 12497317 HT 383. I would imagine that a GM crate engine would have similar Horsepower and Torque numbers.

http://www.high-performance-engines.com/spc1.html

Thanks for the link, Paul.

The GM crate motor is rated at 340hp@4500, 435ftlbs@4000. So it's a bit stronger than the TBI one in your link, but certainly in the ballpark. So I think you're right, it is a very similar motor. Slightly small camshaft, and less compression. Wonder how much these differences will affect the TBI?

It seems that GM has been talking about its own TBI 383 for 5 years now...

--Rob

i think all you would need is a different chip

Originally posted by ryeguy
It's being rebuilt...and I'd like to work with the stock Chevy EFI rather than switch to an aftermarket set-up if at all possible.

--Rob
Turbo City will use a stock TBI unit and pump it up using big block injectors I believe that will flow about 670 cfm. I already talked to them about the same thing in my suburban.

The boys at thirdgen.com I believe will tell you that you can just change the chip in the computer. You can either have one "professionally" burned for you for I think $50-70, or for about $50 you can buy the equipment to do it yourself. If you have one burned for you simply send the a copy of your cam card and specs and supposedly the will make "any" cam work with the tbi.

Charlo

One thing you need to be aware of is the overlap. Most performance grinds are around 110* but EFI works best with 114*-116*.

The only people i know of that do it "prof" will charge $250+

It might need bigger injectors, check into doing it yourself (chip mod), there are more boards around than just thirdgen ;)

Looked into this a while back and was told I would need bigger injectors. Everything else should be fine you just need to move more fuel for the bigger engine or you will be running lean.

I think you'll find that it won't be optimal at all with just larger injectors unless your extreamly lucky. Will it be off enough to cause problems? maybe not, you'll just have to see, make sure you read those plugs if you don't have access to a wide band O2 sensor.