Reply to "Dropped a valve..."

I presume that Chevy valves were used because these are after market heads using Chevy dimensions?
Look at the stem detail in the pictures. Those are cut down stems for greater flow.

That isn't anything that has proven to be a problem in either case though. I use +.100 length Chevy valves in SB Fords (289/302)WITH the cut down stems and they work great. Ford valves are a little short a lot of times and the +.100" length works better.

I guess if you are going to kiss a piston with a valve, the weakest point is going to break. Usually you will bend a push rod, but if the valve gets sucked in something else needs to break?

Still working on the source of the Revs. I think those are the Argentinian ones? same as Farrea.

Regardless of all of this, you still need to find out why the other valves are showing signs of abuse.

Again. I would look at the camshaft profile.

OK. Just heard back from Ted, my valve expert. Here is the direct quote:


"Morning!

Our part number is 11800EPN and 11803EPN, those numbers you mention are Rev products. Rev supplies (or at least used to) an India made piece, produced by Vikram. They don't make valves, they just import them.

Two piece valves are joined in the middle of the stem, not at the head of course so that wasn't the problem.

OK for stock use but not performance, we looked at the brand line but rejected them long ago.

Note the slight bend at the end of the stem, that is classic from an impact. If the head of the valve just fails and comes loose, this almost never happens, so the valve likely bent from hitting a piston first. Usually a good valve will make many many hits before snapping like that, this one let go in just a few bumps.

Plus look at the stem, signs of burnishing? Then the rocker arm roller is gone?

The valve stopped moving, the rest kept going. You might even break one of mine when this happens, pretty severe damage there.

I won't install a Rev valve myself.
Ted"

He's also a retired race engine builder. Lot of experience there...and good judgement.

Hope this helps. Sounds like someone needs to verify piston to valve clearances with clay?