I HAVE A 98 Z28 THAT NOW HAS A 383 STROKER IN IT. THE PROBLEM IS IT WILL NOT START, HARD CRANKING , JUST BACKFIRES TERRIBLY. IT HAS PP STAGE 2 HEADS, COMP CAM .595 .598 232/234 112 LSA CAM IN IT. I ALSO HAVE THE SLP LS6 INTAKE, HOOKER LONG TUBES, MAGNAFLOW EXHAUST,TAYLOR 10MM WIRES NGK TR55 PLUGS AND A STOCK TUNE. I HAVE WENT OVER THE VALVE TRAIN WHICH STILL HAS STOCK ROCKERS AND COMP PUSHRODS AND THE VALVES SEEM TO BE OK, ALSO LOOKED AT WIREING AND IT SEEMED FINE ALSO. THIS CAR JUST WILL NOT START. aNY HELP IS GREATLY APPRECIATED I AM A LITTLE LOST.

 

I don't want to make this sound stupid, but did cam gear and timing gear get lined up right during the cam install?

 

MY FRIEND WHO RUNS HIS OWN SHOP ANS PERFORMANCE SAID HE DID BUT THAT SAME QUESTION IS ACTUALLY RUNNING THROUGH MY MIND ALSO, I JUST DONT WANT TO PASS UP ANY OTHER POSSIBLE CAUSES. THANK YOU FOR RESPONDING I GUESS THE ONLY SURE WAY TO TELL IS TEAR THE FRONT COVER OFF AND CHECK :o)

 

Maybe You Have The Cam In Backwards?

 

Check the cam timing!!

 

If the marks on the cam and timing gear are off just a tooth it will reap havoc. I had a 92 RS that I had to rebuild the top end on. When I put it back together I had the distributor 180 degrees out of wack. Sounds exactly like the symptoms you explained, except yours sound mechanical. No offense to your friend, but unless you saw it for yourself I really wouldn't take anyone's word for it. I have seen entirely to many shops with make shift or backyard mechanics do other peoples stuff and tried to build it like a 1975 chevy 350. I would definately check it yourself.

 

Its probably out of time. I dont think its 180* out of time though because there is no such thing. When you line up the timing gears it doesnt matter if you put the cam gear dot at 6:00 like most people including myself do or at 12:00 because since the crank turns twice to every one turn of the cam its the same thing.

One more thing to check is that the rocker arms are not holding the valves open all the time. If the wrong length pushrod was used then this can happen.

I know it sounds obvious but does your buddy at this shop know that your rockers are bolt down and not adjustable? I seen old school mechanics try and set valves 1/2 - 1 turn past zero lash on non adjustable rocker engines.

 

thanks guys for all the info. Yeah I am gong to pull the chain cover and see whats going on. I will post the results of what I find .

 

check the coil pack wires...could have them flipped or on the wrong side....seen this before...