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View Full Version : Tbi to Vortec heads egr question and what cam?



brewtality
03-10-2008, 05:12 PM
I have an 89 blazer 350 tbi 4wd. Had a host of problems. The tbi keeps catching fire. Ive seen a flame in the intake and when the throttle opens it lights it up. I'm assuming the only thing this can be is a stuck or sticky valve.
Comp test read 173-179 across all cylinders, timing set to zero,(ecm disconnected). So to my point.

I am contemplating doing the vortec head swap considering my problems seem to be head related. If you disagree PLEASE give any input.

I have read tons of material related to the swap and still am slightly unclear on the egr. If I use the GMPP tbi to vortec intake, do I still need to run the egr tube to the exhaust port. I have long tube headers on there now. If that has to be done, can the tube be plumbed to the long tubes?

Also I was wondering any cam suggestions for my setup if I go with the vortecs. Not looking for a rocket but would really like to wake it up. I have the holley 502-6 670 cfm tbi now so I'm hoping fuel delivery shouldn't be an issue. Will replace fuel pump if i need to and would like to get out of the whole project for about $1000. I can get a set of good used vortecs stock for about 200-250.

Any help is greatly appreciated.

Zero260
03-11-2008, 11:41 AM
That tube you're talking about is a part of the A.I.R. (smog) pump system. I've never heard of anyone keeping the smog pump after running LT's. There is a GM pulley replacement for it, if you want to take it off. If you try to run a shorter belt, the belt will throw.

If you run the holley tbi, you might have a hard time running an e.g.r. The t.p.s. sticks out too far, and I had to block off the e.g.r. port for clearance. I'm running a Weiand dual-plane (300-64). Not sure if that would apply to the GM intake.

If you dont do much offroading, I'd go with an LT-4 cam. Run 1.6 rocker arm to get a little more lift. If you can burn your own proms, from what I've read, its an easy cam to tune. Also, you wouldnt need a holley tbi, just a ported/polished 350 tbi with maybe bigger injectors.