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TR4/4A Need Advice as to what to do regarding Engine Compression Problems

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I have heard of valve rescission in a TR3/4. What is generally the cause and/or cure. Does it continue to happen once it has started?

The reason I ask, is ALL Bobs clearances were tight. The number four exhaust took a few turns until I could see the valve stop coming up. The valve clearances were adjusted a short time ago, and set to the standard .010/.012. Why would all the adjustments move that much? All the lock nuts were tight, but none had clearance.
 
Seat recession was always a problem to consider once it gets started, but there are so few heads around that haven't had seats installed and hardened seats at that. When it was the problem, it could be either the cast iron or the valve itself, if you were dealing with original materials. The valves typically were surface hardened and a couple light or one heavy handed valve job would remove that hard surface material exposing the softer metal beneath. If you have a good extra head you can make an approximate measurement of how high the top of the valve stems are in relation to the valve gasket surface. I've got one buried out in the garage if I can get to it I'll measure it tomorrow.
 
Bob-

Longer term, be thinking of some head work potentially - unless the valve adjuster itself was loose the reason you lost the clearance may be due to valve recession as Geo mentioned. If so, you may see the problem return - best to keep checking clearances there to see if it starts closing again. I definitely endorse Westside, they've done head work on two engines for me with good results - I think you'll get good results, and cheaper too staying local if at some point you need to have work done.

And yes, we missed you at autocross - Mr Knucklehead beat me by about 4 seconds on a 60 second course. I'm assuming he skipped a few cones. At least that's my story!

Randy

oops, didn't read the last page of stuff before I posted - looks like you are already on track for head work but at least you can drive a bit while you plan. Westside... can't go wrong there..
 
And another thing that popped in my head: this may fall under the snake oil category, but before I rebuilt my TR4 engine I always added a lead substitute - it might be worth doing that for a while and see how things go. Walmart still carries CD-2 concentrated lead substitute, at least they did around my area just a few months ago.
 
Whats 4 seconds among friends? I did not skip any sections. Also, I'll have you know that I did not knock down any cones all day (that I am aware of), nor do any of the few hundred pictures Bob took show a cone under my car. I think Randy is clear in that regard as well. However, this is my favorite picture. It's slightly out of focus, but it is raining. You can see how close I came to the last hair pin curve gate -the rear end actually slides around the cone. That is a tough act to follow! I am now convinced my TR3 runs as good (or better) than new, but doubt it moves my title up to "Mr". -I'll stop stealing the thread now...

Why would the intake valves also recede? It makes sense that #4 exhaust would be worst, assuming it is the hottest, but all the intake valves were extremely tight -the other 7 rockers were about the same and none of the lock nuts were loose. Generally I avoid snake oils, but if I were Bob, I'd be looking at some lead additives and watching the valve lash.
 

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