Valve Adjustment/Wear

[glemon]

I reset the valves after the first 500 miles or so on my rebuilt motor recently. I have read a lot about valve recession, and I thought with a rebuilt head everything might settle in a little bit and I would have tight clearances. To my surprise none were tight, about a third were still in spec, and the rest had a little to a lot too much clearance. I did not measure, but some were pretty lose, I tightened them all up, the engine sounds better now (less valve clatter).

But it got me curious, I understand what would close the gap, but what would make the gap bigger, only thing I can think of is wear to the rocker shaft or the valve stem ends or rocker ends, but I wouldn't think that would amount to much over 500 miles. I am not that worried, but just curious about opinions, is this more or less normal, and what would the typical cause be?

Thanks Greg

 

[TomMull]

Greg,
I have had the same experience myself but attributed it to my ineptitude in making the initial adjustments. I re-adjusted as you did and had no further issues.
However, judging from posts on other forums, there are some very bad things that could cause your condition, soft lifters/ cam lobes, inadequate lubrication (upgraded lifters have an oil hole) improper run in, and modern oils. I've never experienced any of these and have recently rebuilt (not yet run) my Tr3 engine with no upgraded parts. I'd say not to worry.
Tom

 

[TR3driver]

(upgraded lifters have an oil hole)

The hole isn't for added lubrication. The theory is that it lets the oil drain out of the lifter that would otherwise be trapped there and make the lifter heavier than it needs to be.

But everyone that has looked into the issue says it makes no difference at all to the effective weight, since while the engine is running, the action of the camshaft will bounce all the oil out the top anyway. And it weakens the lifter, which is not a good thing.

I'd stay away, since lifters with the hole may be "dis-upgraded" in other ways as well.

 

[glemon]

I wasn't real worried, I am actually more worried now, hadn't thought of the fact that even when there is no force on the rocker the pushrod is sitting on the lifter, which is sitting on the cam (although now that I think of it not on the lobe, I would think most if not all cam wear would occur on the lobe, not the part of the cam that does not lift the lifters, though lifter wear could cause it).

Anyhow, use Brad Penn oil and plenty of Moly Lube for break in, will check again in a few hundred miles or a few months, whichever comes first.

 

[Don Elliott]

I suggest that you remove the entire rocker arm assembly and turn it up-side-down to look at the rounded ends of the rockers. That's why Tom Mull suggests that the rockers may be soft. If you see a flat oval indent on the rocker end where it impacts on the top end of the valve stem, it means that the valve gap (rocker gap) cannot be set correctly with a feeler gauge. The step upwards into the originally rounded end gives you a gap dimension of the feeler gauge you are using PLUS the amount of wear on the end of the indented rocker.

I have often re-radiused the indent out of the rocker ends till they were rounded again. I did this with a hand grinder or a bench grinder. Then I re-assembled the rocker assembly, re-set the gaps correctly and everything stays fine for about the next 50,000 miles or more. I'm still using the rockers, bushes and rocker shaft that came with my 1958 TR3A brand new. So if the rockers are "soft", mine are still in the hard (heat-treated) zone or they were made naturally hard before the TR left the factory.

BTW it was 11 years ago and 86,000 miles that I had 8 new valves, 8 new guides and 4 exhaust valve seat insert rings installed at an engine re-build shop and have had no issues since. I check the gaps every 5,000 miles or so and have never had to re-gap the valves more than a thou (0.001") at any time during the past 11 years.

Last weekend, I drove my TR 860 miles with no problems anywhere.