Valve collision problem Options

[thomasotten]

I am having a bit of a problem with my latest 2 liter build. Basically, valves are colliding with pistons after warm up during break in. A valve got stuck and the pushrod actually fell off the rocker.

The heads were redon by RIMCO. After the problem happened, I pulled the heads, and there was clear indication of valve collision, and I had a valve stuck open. The head with a problem was sent back to RIMCO.

Reinstalled. What happened this time is the engine start up from cold, runs fine. But then I can hear the taping of collision again. The taping is accompanied by a chirping sound that sounds like something is dragging. I think it must be the valves dragging and closing too slow.

I have a deck height of .065.

This is essentially a stock build, stock camshaft, etc.


Any ideas? Is this perhaps a valve stem lubrication issue?

[bdstone914]

I am having a bit of a problem with my latest 2 liter build. Basically, valves are colliding with pistons after warm up during break in. A valve got stuck and the pushrod actually fell off the rocker.

The heads were redon by RIMCO. After the problem happened, I pulled the heads, and there was clear indication of valve collision, and I had a valve stuck open. The head with a problem was sent back to RIMCO.

Reinstalled. What happened this time is the engine start up from cold, runs fine. But then I can hear the taping of collision again. The taping is accompanied by a chirping sound that sounds like something is dragging. I think it must be the valves dragging and closing too slow.

I have a deck height of .065.

This is essentially a stock build, stock camshaft, etc.


Any ideas? Is this perhaps a valve stem lubrication issue?

The first thought is what did Rimco do when building the heads. They have a poor reputation for quality work.
Is this a basically a stock build?
How much lift is on the cam, what size valves are you running ? Aluminum or steel pushrods ?

Maybe you need pistons with a valve relief ?

Deck height as measured is not a direct measurement of the clearance from an open valve to piston due the valve angle and diameter.
That distance can be measured using clay ( or other formable material ) on the top of the piston, turn the engine over by hand slowly. After removing the head you can slice the clay to see the minimum distance that the edge of the valve to piston.

Regarding valve to guide clearance, should be correct as the guides come out of the box. Were the guides checked and replaced if needed ?
Since Rimco had the heads twice and the problem persists I would be looking for a better place to identify the problem.
Or pull the heads, remove the valve springs and check for clearance. If you have worn guides the valve can deflect at the tip.
.065" desk height should be more than enough if all other things are correct.
I am not an engine expert but I did once sleep at a Holiday Inn Express.