Hi guys,
Just finished a 383 stroker build for my '99 Yukon using the original 5.7 Vortec. I went with a ZZ4 cam and 1.6 roller rockers. It's back in the truck and I'm having a hell of a time getting it timed correctly. We're really close, but still getting some backfire through the throttle body. We've reset the motor to TDC and reinstalled the distributor several times and just can't get it going.
Any one else had similar trouble getting the timing right?
Thanks

 

You need a tech II to set the timing up correctly, you can get it close but there is a certain range that the computer needs to see to be happy.

I will also state the obvious, check your plug wires are going to the correct locations. Been there, done that...

 

Yeah, I think you're right. Already checked the wires just to make sure, just in case! I'm going to pull the valve cover, which I've been avoiding because have to pull the ac bracket, etc.. to get it clear. But, I want to verify #1 TDC and see where the rotor's pointing. I think it'll help to have a visual on the valves of #1 to make sure we're exactly where it's supposed to be.

 

Are you getting a code ? Have a look at this video,it might help.I have not heard of anyone have have a perfect running 96-99 vortec thats been stroked and cammed do to the lack of fueling and the cam and extra cubes effecting so many other things.Maybe others have,if so maybe someone here can post links and steer you to the gurus.

 

There was a JET program that was the old TunerCat program that can tune the old Vortec computers. Not sure if it is still for sale. It also works on later LS combinations.

And supposedly the GM crate HT 383E will run with the stock computer but has a milder cam.

 

Yes, they still sell it. It's not as nicely laid out as other products but it can get the job done if you know what to adjust.

 

My Old 98 Tahoe with a mild built 383 ran on a EFIlive speed density tune for 6+ years before I sold it. It does need timing and fuel adjustments to run 'well'. I was on the verge of running out of fuel with my truck on the new style spider injectors.