Technical Valve Stuck in Guide?!?!

Had one like that in my super cobrajet. Freshening the engine and had valve guides replaced. Ran great for maybe a thousand miles. Took it to the drags for the first time after work done (at a major ford dealer and watched them do it) ran several runs and started a clatter on the way home. Pulled a valve cover and could see one exhaust valve stuck part way open. That one valve was the only problem lucky it didn't kiss the piston. It was stuck so hard a hammer couldn't drive it out.

Naturally back to the dealer and they checked all the rest of the valve stems for clearance it my INSISTENCE and they were all in spec. Replaced the guide, pushrod, and valve and never had another problem for the next 10 years while I had it.

 

Bent valve, it doesn't take much. I'd roll it on a piece of glass or get a machinist to look it over between vee-blocks.

 

I should be able to visit with my machinist today to see what he found when going through the heads. If I remember right, I think most of what he did was likely just surface them and check them to make sure the valves were sealing since they were so new. I suspect the fit of valve to guide was just as GM sent it out which was at least too tight on this one valve. Anyway, the heads I am putting back on it for now were on it about 10 years prior so shouldn't have the same issue. We will fully pull these heads apart to check clearance before I run them again. They at minimum need the one exhaust valve that stuck since it is bent pretty good in addition to the galling on stem from when it smacked the piston.

Anyway, thanks for all the help talking through this guys. I know I learned some things and hopefully this can help others pay attention to some of this stuff as well especially when dealing with new "correct" stuff.

 

you are running lean. I had the same issue with my hemi. Best to dyno it next time. They can tell immediately and fatten it up.

 

Just got off the phone with my machinist and he actually didn’t even pull the exhaust valves on these heads since they were sealing and only had a couple hours run time on them. Pretty sure my biggest issue is that they were likely borderline on clearance for a naturally aspirated engine. Considering a supercharged engine needs a little looser fit, I think it just bit me. Thanks again for all the help guys.

Got some parts from Summit today so should have it all back together Monday with the other heads. And, we will obviously be checking the fit of all these valves in this set of heads before running them again.