Just got done with the the engine build and at first after cranking it over a couple times to build oil pressure it started once i connected the coil pack harness connectors and fuel pump fuse. It ran absolutely fine for 30 plus minutes, then we shut if off. After checking for any leaks we tried to start it again and no luck it would crank like it wanted to start over but it didn’t and now after five times trying to start over it just cranks and spins the motor but it feels likes its not building compression and its misfiring. Already checked for fuel and spark and those are good. I decided to remove a valve cover and found number five cylinder intake rocker arm with a little up and down play. I rechecked the pushrod length to be sure and came out with 7.475, and i installed 7.400 comp cams pushrods. It has brand new LS7 lifters and a TSP VVT 4.2 cam with stock head gaskets and unmilled heads and block. Can the .075 be enough for the engine not to build compression or can the problem be internal or even something else? And how would it start and run fine at first for 30 plus minutes and then not wanna start? I apologize in advance for the lengthy question.

 

Check your crank sensor and all grounds. Something might have loosened enough to allow it to run at first, but might have loosened more on shutdown or while trying to start again.

 

Theres signal from the crank sensor and I’ve already checked the grounds and all are good, and all i get is a bcm code for my left rear turn signal.

 

Then check all connections. It's bound to be something simple.

 

Will do but it still definitely sounds like its not building compression and its just backfiring outta the headers.

 

Were the coil harnesses put back on correctly? I've seen more than once (or twice...) where that happened with results as seen here.

 

Yes they we’re and are put back correctly, i see spark when i pulled a plug from each side and tested them. And there’s fuel as well.

 

You WILL see spark, but at the correct cylinder?

 

If it does not sound like it is building compression you better do a compress check. Mighta had a ptv contact. In fact, do compression test now

 

The car literally sounds like this one while cranking.

 

Your valves are bent I am too familiar with that sound.

 

I’ll be checking compression as soon as I get a chance, but the questions is how, if they got damaged, did it happen? If I ran the exact same setup for three years without flaw.

 

I once had one that the timing chain stretched and it jumped timing when the chain slung. I once had one the chain broke altogether.

Thread title says freshly built though....

I had thought possibly cammed but no phase limiter so vvt kicked in as possible explanation on a new build.

 

It has a phase limiter that I installed from tsp into the vvt cam sprocket, it also has a brand Katech C5r Timing chain

 

I do not know what else to tell you. You will know more when the heads come off. So sorry. Believe me I know what a punch in the dick it is to have to tear apart a fresh build.

 

Just thought of this -- possible install one tooth off and even with phase limiter it phased too far...?

 

I highly doubt its the timing since it started up instantly and the phaser was left there since the same exact cam setup from prior. I’ll update as soon as I can run a compression check, i just hope its not too expensive I already poured 9k into it.

 

I hear you man. Good luck.