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TR6 69 TR6 engine suggestions - cause for burnt valve?

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I

ichthos

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Last summer, I took a cross country trip to see my son and ended up burning an exhaust valve on my way home. I pulled the head, got the head rebuilt, rebuilt the rocker assembly, but then got too busy with school to do anything more. My car has been sitting ever since. I plan on doing a full restoration at some point, but for now I need it for a daily driver.

I have about three weeks left to do some work, and this is where I need some advice. I could just put everything back together, but it doesn't make since to do this if there is something else I am overlooking to begin with. So, what causes an exhaust valve to burn in the first place? I should let you know I did do some stupid things that may have contributed. I pulled a small loaded trailer during my trip. My distributor was also destroyed on the way there. I didn't realize how worn it was, and the wobble got so bad that the inside of my distributor cap got machined out. A piece broke off and destroyed it. This all happend less than 60 miles from my destination, and I had no choice but to hobble in. Luckily I was right near The Roadster Factory, and I was able to get a rebuilt one. Any help is greatly appreciated. Thanks for your help, Kevin
 
Weak valve springs and lean mixture are probably the two most common causes; but of course general wear (leading to poor sealing) will do it too.

Hopefully they checked (or replaced) the springs during the rebuild, so I'd just put it back together and be alert for signs that the mixture is too lean. ISTR a 69 doesn't have a mixture adjustment, but you can substitute carb pistons, domes & needles from a later car to get the adjustment.
 
Kevin, welcome back. As I recall, your engine was really tired. A lot of things, as Randall pointed out, can cause the burnt valve. In your case, we will probably never know, but now that your head has had a valve job, and the rocker assembly rebuilt, put her back together and things should be fine.

That said, once assembled, and valves adjusted, do a compression check to get an idea of how the rings are doing. If all are low, but within a few pounds of each other, it will tell you you have worn, but no broken rings.

With three weeks remaining, you should have it going in time for school.

Good luck
 
Thanks, guys. I am finishing up a total restoration on a Bugeye Sprite I promised my wife years ago, and then I will be making a mad dash to get the TR up and running before the end of the month. It has not been fun having no car for the last year. I really just want to drive for a couple years before I do any more restoration on the TR6. Thanks for the advice. It was kind of what I wanted to do any way.
Kevin
 
Don't forget timing. Carbs that are borderline lean and timing too far advanced can be a deadly combo for valves.
 
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