HELP! uneven valve stems

[THE78II]

Are uneven valve stems acceptable on a reconditioned set of heads? I was surprised to find one of them has an exhaust valve 1/16" shorter than the intake valve. Seems like a lot to me, but I've heard of it before. Can anyone offer any advice? It's not a racing motor, so it won't see high r's. Thanks fellas.

 

[Wart]

If the head was rebuilt by a reputable shop unless they suffered a massive brain fart it will be ok. But if hte heads were reconditioned by a fly by night shop you may or probably have something to worry about.

What you need to do is figure out why the valve is a different 'length/height'. They may have replaced one valve and seat and ground the remaining valves and seats. This certintly would give differen't heights. If they over ground and knife edged the re-used valves it certintly would add up to differences between valves.

Just throwing an eyeball on the heads should give you a pretty good idea what's going on.

 

[Vince]

What type of head is it? You mentioned in your other thread you had a choice between rail-type or pedestal-mount rockers. I assume you're using a hydraulic cam & lifters? So you'll need .020 to .060 preload on the lifters. Bolt everything up and check to make sure you're in that range. If not you have a problem. If you have pedestal rockers you should be able to shim them to get within this range. Ford sells a shim kit for their pedestal-mount roller rockers. I think this would work with the stamped pedestal rockers too. If you have rail rockers, I'm not sure if you can do anything except get a new head (or maybe a new valve).

 

[Wart]

What type of head is it? You mentioned in your other thread you had a choice between rail-type or pedestal-mount rockers. I assume you're using a hydraulic cam & lifters? So you'll need .020 to .060 preload on the lifters. Bolt everything up and check to make sure you're in that range. If not you have a problem.

Not really.

Pretty much as long as the lifter collapses some (short valves) and doesn't bottom and has some play (tall valves) it ought to be fine.

Ther real issue is the rocker tip maintaining 'proper' contact with the valve stem.

 

[Vince]

Another thought...Ford used a hardened steel cap on the exhaust valve with rail rockers. Could be the cap is missing.

 

[THE78II]

problem solved

I bought the newer type heads, with the fulcrum/pedestal setup.
Found out that the stem lengths are different due to valve seat reconditioning.
Thanks to all for your replies.