You cannot do a compression test with the rockers off....

You can do a leak down test.
Will

 

Makes sense then, no leak down was holding air fine. I just realized that no air could get in if the cylinders if the rockers were off...

 

Never had one gush water either.... I use Teflon thread lube/sealant on all bolts that enter the water jacket or oil passages


Mike

 

After taking the drivers side valve cover off, I discovered one of the rockers spun sideways (and damaged) with the half moon keepers for the valve laying in the valley below (it had not made it into the engine thank goodness). The spring had not come all the way off, the rocker arm was barely holding it on.

When I got both heads off, I found no damage to the pistons or cylinder wall.

I called the guy who rebuilt the engine for me and he said he will fix it, but says there must have been something defective with the GM hot cam kit I bought. I am trying to figure out what happened.

Both heads had small springs laying in them when I took the valve covers off, which come from the rubber valve caps I believe (see pics in 1st post). Only one valve was damaged, that I mentioned above, valve seems fine, just the keepers (two half moon shape) were off it.

From reading what is posted here, I am thinking he did not take into account the hot cam and adjusted the valves incorrectly? Would this have caused this damage? Would it have possibly damaged the cam?

Or could it be that the push rods are the wrong length? He purchased them, they did not come with the kit.

Thanks for all the help!

 

[QUOTE=jmh139;1584140794]After taking the drivers side valve cover off, I discovered one of the rockers spun sideways (and damaged) with the half moon keepers for the valve laying in the valley below (it had not made it into the engine thank goodness). The spring had not come all the way off, the rocker arm was barely holding it on.

I called the guy who rebuilt the engine for me and he said he will fix it, but says there must have been something defective with the GM hot cam kit I bought. I am trying to figure out what happened.

From reading what is posted here, I am thinking he did not take into account the hot cam and adjusted the valves incorrectly? Would this have caused this damage? Would it have possibly damaged the cam?

Thanks for all the help![/QUOTE)

I looked up what the original LT4 rocker arm part number was for the then unique , one year only, pedastal mount : 12557779;

I then looked up what comes in the LT4 hot cam kit: 809-19210729;

I then looked up 809-19210729 in the 2012 GM Performance catalogue and read this notation: "similiar to 1996 Corvette LT4 engine except trunnions have been machined for EARLY 3/8" ROCKER STUDS (emphasis added).

Soooo, if your machinists just installed the Hot Cam kit, and didn't remove the original LT4 pedestal rocker studs and replace them with early style 3/8" rocker studs, everything was probably doomed from the get go.

The up side, no irrepairable damage was done to the engine. And if it makes you feel any better, even when the stock so called "self aligning" rockers are correctly installed, it is not unusual (in my experience) to find one askew on the valve stem tip. I think the locating "ears" are a little too small to be 100% effective; but thats just my opinion.

 

While you have everything apart - you might want to consider going with Better Valve Springs and Better Retainers. The factory stuff is certainly not junk, but I've personally seen two retainer failures with the LT4 spring retainers (both of these happened at HPDE events), and both involved a valve contacting a piston. Comp Cams, Crane, Isky, Manley and others all make hardware that will stand up to hard use better than the factory stuff. Generally speaking - you want a valve spring that has at least 0.080" difference between the lift (at the valve) of the cam you're using and "coil bind".

Don't take my word - ask a couple of Engine Builders (not general mechanics - but guys who make their living putting together engines that will be used in High Performance / Competition applications) what they think of factory springs / retainers.

Just my $0.02

 

I finally found my paperwork and he installed ARP 134-7101 rocker arm studs, which I think should be fine from my searches, at least others have used them with LT4 heads
http://www.summitracing.com/parts/arp-134-7101

Push rods he used show LLP LPR-5-7150 but I cannot find that part number online. Pushrods are labeled 1912 7.150" X 0.80 WALL

Valve guides: SBI 140-8180
http://www.cnc-motorsports.com/valve...-140-8180.html

Everything else came from the GM LT4 Hot Cam Kit
http://www.summitracing.com/parts/nal-12480002

Also this information is listed in the paperwork:
Intake Valve Lash: 1 +/- 1/4 TURN DOWN FROM ZERO
Exhaust Valve Lash: 1 +/- 1/4 TURN DOWN FROM ZERO
Lash Adjustment Method: ADJUSTING SCREW

Again, I appreciate everyone reading and commenting on this. Jay


[QUOTE=mtwoolford;1584144381]