`96 tahoe - Replaced heads, timing problem, or?

[Blind]

Back story:
I have a `96 tahoe sport with 121k miles.

About 5 years ago, it started mixing coolant into the oil pan very badly.
It was my brothers at the time, and he replaced the intake gaskets but the problem remained, he parked the truck on non-op and just let it sit until about a year ago when he gave it to me.

I pulled it down to a shortblock and had the heads and headgaskets checked by a reputable machine shop, a blown headgasket was found along with a crack in one of the heads.

I purchased replacement chevy vortec heads from summit racing, along with gaskets, problem solver intake gasket set, thermostat housing, new heater bung for the intake, new thermostat, new head bolts, new stock ratio GMPP rockers, etc etc.

I followed the chiltons book procedure to set the rockers, and I went through it twice. I also followed the books guide on how to set the distributor back in to set the timing (line up the dots on the distributor, point the rotor to the 6 or 8 stamp on the cap with the crank index points pointing to the marks on the timing cover, etc). I did have a problem with getting the distributor to lock into place by tightening the hold down clamp and bolt, if I installed the hold down clamp upside down would that make it impossible to lock down the distributor so it can't rotate? I can get about 5-10* of movement out of it right now.

I got it all together recently and fired it up, but it runs very rough, the SES light is lit, and it lacks power. It sounds to me like the valves are bleeding compression back into the intake while it's running.

At this point since it runs I drove it around the block and it drives well enough, I believe I need to take it to a shop to have the timing set up correctly, but could the timing being off be the cause of the odd sound and extremely rough running?

this isn't my first engine top end replacement, however it is my first time doing this kind of work to a GM, I have a few mustangs that I've taken apart a few times, so to say the cylinder numbering being different on this motor than my SBF's threw me for a loop when I was setting up the rockers is an understatement...

 

[retorq]

Sound like maybe the pump drive rod isn't fully engaged ... I would double check the timing too, make sure it's dead on where it needs to be. Good luck.

 

[Blind]

Thanks, I removed and installed the distributor a couple of times trying to get it to lock into place, it feels bottomed out to me, but that must be it.

timing is very hard to verify on this motor, with only the mark on the balancer and the stamped pointer on the timing cover to line it up to, then have to pull the rotor cap to see where the rotor is sitting is a bit silly. I know I'm in the ballpark because the engine runs, hah.

 

[steamroller]

What's the code for? If it's P01345 it's the cam/crank sensor correlation. You can't use a timing light on them like the older engines. You'll need a scanner that reads the cam retard offset, ideally you want it at 0 degrees, but as long as it's it within a range of + or - 2 degrees with the engine above 1000 RPM you're good

The readings can change just by tightening the clamp down, that's how sensitive they are

 

[retorq]

Thanks, I removed and installed the distributor a couple of times trying to get it to lock into place, it feels bottomed out to me, but that must be it.

timing is very hard to verify on this motor, with only the mark on the balancer and the stamped pointer on the timing cover to line it up to, then have to pull the rotor cap to see where the rotor is sitting is a bit silly. I know I'm in the ballpark because the engine runs, hah.

You should be able to mark the base of the distributor with the #1 plug tower, line up the marks on the balancer and timing tab so they are at 0, then drop the distributor in, line up the rotor with the mark and tighten it down.