5.7L intake

Just did an intake on 97 silverado 5.7L

Truck fires up but the rpms bounce up and down 500rpms like 1000 to 1500 to 1000 to 1500.

Any ideas?

distributor seems ok. TDC #1piston the rotor is pointing to #1 on the cap and the rotor is pointing to the 8 on the distributor housing.

If you didn't mark exactly where the dist. was removed from and put it back exactly the distributor phase is out, I think they call it cam timing. It must be corrected with a scan tool I think. I had mine checked at a dealership. The manual says it will run as much as 12 deg. out but not correctly and the check engine light will be on. I've changed seveal of these, before I loosen the dist. I remove all plug wires and lay a 6" scale across the drivers side of the cap and make a mark on the fire wall. After replacing the gasket, reinstall the dist. to this location with the button facing the location it was removed from of course. Hope that helps.

First of all make sure the A.C. is off. it runs in the defrost mode as well as in A.C. mode. Timing should not be off. 97's distributer is pinned. You may have a vacuum leak. Sorry. Good luck!

I had a simaliar problem with my 97 check the mass air flow sensor make sure its plugged in if so try replacing it.

it was the MAF. thanks

can we clean the intakes with a whiz wheel? on the head side.

I heard there was problems with 4.3L Blazer when doing intakes.

5.7L ok?

First of all make sure the A.C. is off. it runs in the defrost mode as well as in A.C. mode. Timing should not be off. 97's distributer is pinned. You may have a vacuum leak. Sorry. Good luck!

Could I ask what are you refering to being pinned? I've changed quite a few of these and I don't understand what you're speaking of. Its true the timing is not adjust able by rotating the distributor, but phase is, anyway my 97 350 was not pinned in place. I turned the distributor while my buddy at the dealership read the scanner. :uhoh: I use one of the 3M scotch brite wheels to clean intakes when needed.

I marked the distrib. put it in and everything. had the boot and vortec box off when trying to run causing it to hop up and down rpms.

3m scotch wheels on the head side? of intake?

heard on 4.3L's its bad and if you get material in there it kills the cam bearings

Yes, the initial position of the Cam Position Sensor (in the base of the distributor) can be adjusted. It doesn't HAVE to be done with a scan tool, but it's easier. Without a scan tool, you can verify the position of the crank (CKP), then set the distributor CMP in phase with the leading edge of the signal AFTER the CKP. It may run with the CMP out of phase, but probably in batch-fire mode rather than sequential.

Gettign any contamination down the runners is probably a bad thing, regardless of what engine you might be working on.