camz28ryan

just got my freshly rebuild 1996 lt1 back and all put together, its bored .30 over, cc503 cam, new opti spark, its the vented opti by the way. and were trying to start it for the first time since we pulled the motor, and it keeps backfiring, why is it doing this? we dont have the opti spark vent nippe hooked up cause we dont know where it goes. could that cause it, and where does it go? we double checked the wires and made sure they werent crossed or on the wrong cylinder.

Injuneer

Is it possible you got the cam dowel in the wrong hole in the back of the Opti?

Shoebox shows you where the vent and vacuum lines go. But that won't prevent it from starting.

http://shbox.com/1/opti_vacuum_harness.jpg

http://shbox.com/1/opti_vacuum_conn.jpg

camz28ryan

thats what we were thinking.. but theres only one way the cam dowel will fit in the opti spark the right way, correct? we have the old cam and opti spark and it seems the dowel will only fit in one of the holes.

Injuneer

I've seen people not get it into a hole at all, and others manage for force it into the wrong hole. Happens all the time.

That sounds obscene.

raroz28

at #6 TDC both the cam gear will be at 6, crank at 12 and cam dowel at 3. If this is off the car will not run properly.

Obviously double check the plug wires that they're in the right spots and are on tight.

Make sure that the valve lash is properly set.

camz28ryan

Just a update, my son installed the opti wrong. Some how he managed to install with dowel pin in the wrong place. He missed the hole, typical for a 17 year old boy. Lol

Injuneer

And next time I post that it's possible, someone will post that it's not possible

camz28ryan

Yes you are correct. We had the old cam and old opti out of the car looking at it, and my exact words were, "there is no way you could have done that". To me it looked like it would have broke the aluminum brackets before he could have tightened the bolts flush to the block.