I have a set of siamesed '86 GM runners I'm swapping for a set of SLP's on my '86 IROC. These are the later non-cold start injector type, and I know I have to plug the cold-start injector and reprogram the prom to make that work. Not a problem, but I realized the plenums in the later SD versions are different from the MAF versions. Mainly the fins on the top are further back and the IAC passage. That passage in the MAF plenum goes to the small tubes running along each side of the factory runners, into the manifold, for IAC. Should I be worried about these for the new SLP's? I bought them used from a '91 Z. I heard of people doing this, just want to be sure. Also, anybody refresh my memory on plugging the cold-start passage? I'll be buying a new manifold bae anyway, so do the newer ones lack this passage? Thanks for your help

 

If the SLP runners came from a 91Z, then the cold start passages *SHOULD* be blocked off already. You will just need to remove the 9th injector and re-program the PROM like you mentioned.

There is also a MAP boss hole in the passenger rear for speed density, at least on the stock runners. I am assuming SLP also has this hole. Just plug it up, since you are MAF.

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1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

Cool! Easy enough. Thanks!

Anything about plugging the 9th injector? I don't have the fuel rail in front of me right now, but the 9th injector should be removable by unscrewing the fitting and plugging it with a cap of some sort? Usually I buy the correct parts, but this is a mismatched low-buck setup.

 

Your new runners should come with the 9th injector port sealed off, so you shouldnt have anything to do but install the runners.

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1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System