LT4 hotcam in 350 TPI - won't run?

[Pampered-Z]

I know the car needs tuning ( Jon ), but the car won't even run without about 30 degrees of advanced timing. Â*Just want to know if this is normal? Â*

car is a 88 GTA 350 auto. Â*GM hotcam - 525/525

The car sounds as if it's missing badly, as if the rockers are set to tight ( 1/4 turn lash) and the springs as suppose to be good for over 550 lift.

So does it sound like just tuning or could something be wrong?

[Ian]

30 degrees of timing?!?!?!

something sounds wrong to me, but you might want to wait for one of the "big guns" to chime in. Is the distributor in the right way? maybe the cam got installed retarded (degree-wise not IQ wise, hehe) Just a couple of thoughts.

[Fasterthanyou]

That is far from normal. 88 makes it the $32 mask with the 165 ecm... it's MAF. It shouldn't have much trouble getting a stable idle with the MAF so long as the injectors size matchs what's in the chip.
I'd pull the covers off and check the valvetrain for everything. How did he set the lash, hopefully zero.
Might check that the distributer wasn't installed 180 degrees because a sbc will run, not well, but will with it that far out of wack.
Next thing to check is the plugs, the plugs tell the whole story. See if the're fouled from being too rich, white and chalky too lean, etc.

[Batman]

I got money on the distributor 180 degrees out. Check that first and make sure it is firing on the right cycle then pull the plugs. You didn't drop or bang the MAF did you? MAF's are pretty delicate. Did you clean the MAF? if so what did you use? Some cleaners leave residue and that will screw it all up too.

[Pampered-Z]

Thanks, those are some good things to check. Â* Yes, when I put a timing light on it, with the ECM connection unplugged the timing mark as straight up @ 12 O'clock. Â*Any less and the car won't run unless it's at 1/2 throttle! Â*

My first thought was that the distribitor was maybe a tooth off and that was throwing the computer off. Â*Never thought about 180 out!

Lash as set 1/4 turn past zero.

I'll give him these things to check and keep you posted.

[Street Lethal]

Originally Posted by Pampered-Z

I know the car needs tuning ( Jon ), but the car won't even run without about 30 degrees of advanced timing. Just want to know if this is normal?*

Car is a 88 GTA 350 auto. Â*GM hotcam - 525/525. The car sounds as if it's missing badly, as if the rockers are set to tight ( 1/4 turn lash) and the springs as suppose to be good for over 550 lift. So does it sound like just tuning or could something be wrong?

I'm going to go with the valves being set too tight. Set you're valves the true Hot-Rodder way, and tighten them down individually with the engine running (in youre case, you'll need to back off on each one first, then tighten).

Once the clacking goes away for each, then tighten 1/2 turn. Do one side, shut engine, wait for engine to cool, then do the other side...

I installed a similar grind from Crane when I ran a 400 small block, and the MAF adjusted just fine by itself (after fuel pressure was cranked up, of course).

Out of curiousity though, did you disconnect the ECM when you swapped cams, and if not, did you reset it?