chavie77

Ok. So I just finished installing TSP 's newest VVT-4 cam kit , which included cam, springs, seats, and rods into my 2013 L96 6.0 which is going in my 68 Firebird. Also installed comp cams phaser limiter kit provided by TSP as well. All went without a hitch so far. After I installed the phaser and the timing belt at TDC (camshaft at 6 o'clock and crankshaft at 12 o'clock) the engine gets stuck when I rotate it by hand. I'm using a 22 socket and breaker bar. It's seem to always get stuck when the engine make a full rotation and goes back to TDC. I have to back it up just a little counterclockwise then commence going clockwise again and it rotates fine till the next full rotation and gets stuck again. Anybody have any idea what is causing this. Could it be the timing, alignment or something else. Any help would be appreciated as the timing cover is still off.

chavie77

I took the spark plugs off, could there still be that much compression at TDC?

KCS

iTrader: (20)

Sounds like a piston to valve clearance issue.

chavie77

TSP site states it's got a .635 lift, you may be right. PVC may be an issue. I will call them today and ask them. They are pretty knowledgable and they swore it would not be an issue.

lsxRanger94

I would check the phaser because it could be allowing too much movement( up to 52 degrees total stock). piston to valve issues will not let you back it off and go forward again. It will stick in the same place and not let you go forward no matter how many times you back it up.

Are you using the same length pushrods or custom due to different geometry.

lsxRanger94

L99 engine only has 30 degrees cam phasing. Since you limiter only takes out 20 degrees you need to change to a L99 phaser instead of you L96.

KCS

iTrader: (20)

Good point. There are also two different cam cores as well, if I'm not mistaken. If the incorrect combination of cam core and phaser is used, timing could also be different than intended.

lsxRanger94

Also, when turning the engine over by hand use a ratcheting torque wrench not a breaker bar. That way you will know if things are binding up elsewhere.

bczee

iTrader: (12)

Did you try and loosen all of the rocker so the all of the valves are closed, spark plus out and the then try turn the crank over. If no resistance, then yeah .. PVC...

chavie77

So after extensive communication with another member tsnow678, who by the way has been a lifeline very knowledgable, I think there is another underlying issue with my engine.

So I loosened the number #1 rockers and rods only. I decided to rotate the crankshaft and presto, doesn't get stuck and multiple rotations. So I proceed to tighten the #1 exhaust valve rocker and rod (leaving intake loose)- the engine rotates, no problems. Then I tighten the intake rocker along with the exhaust rocker and "bang" it gets stuck. On top of that as I started rotating the engine, I decided to do a compression test. Every cylinder had compression except piston #1- no compression

So I follow tsnow679's advice and proceed with the following "Pull both rockers off of number 1. Now connect an air line into the spark plug hole on #1. If you do not have an adapter you can make one out of an old spark plug. Or you can use an air nozzle with a large enough end to essentially plug off any air from escaping from the plug hole. Now push air into the #1 cylinder and check to see where the air is going. If you bent the intake valve it will escape through the intake same with the exhaust. With both rockers off both valves should be sealed shut. if air doesn't escape through the intake or exhaust it may be escaping through crankcase which is not good. This would indicate a cracked or broken piston. The air will escape a little around the piston but should not be extreme. Your mainly checking the seal at each valve. Usually with a bent valve you can look across the valve tips and if one is bent it will sit lower than the rest of the valves since it is not fully seated(bent)."

Here are my results. Hooked up compressed air 90 psi into piston one spark plug. Air definitely comes through exhaust valve, and intake (not so much though). However, I began to freak out because I heard faint air go into the crankcase too. So I went ahead and removed rockers from piston 3, hooked up hose- No air leaking from valves but I still hear air going into the crankcase. It would seem so air will leak into the crankcase because of the gaps in the end of the rings. But it seems I have slight bent valves on piston one.

I will take care of this bent valve issue first, then since I will have the heads off I will attempt to check PTV clearance using the model clay method- that still worries me.

By the way, I spoke to Gary from TSP and he said they had never had an issue with PTV clearance when using their VVT-4 cam kits on the ls engines. Ironically they only use phase limiter 5454 instead of the 5460 which is for my engine. According to TSP, all their cam designs have based off the comp cams 5454 phase limiter and proven to work.

lsxRanger94

Don't forget to replace that push rod too, it is probably bent also. Glad you found out about what phasers they use for their cams because that's typically not the case. Very useful info.