View Full Version : Valve cover clearance

03-31-2013, 02:01 PM
Ok, so maybe just one more question before this baby's ready to roll for the Spring.

I was fillin' 'er up with oil when I noticed the rocker arm was really close to the valve cover. Then I noticed notches on the rocker arm from contact with said valve cover. Pictures!

So I took the cover off and most of the other rockers seem to have the same problem.

Of course, I have noticed noise, but there had been a lot of noise with this car until I got it to this point, so it's been relatively quiet! I didn't change the gasket after the valve adjustment, so I'm thinking I just need a new, thicker one. The old one hasn't leaked, but it has gotten pretty flat. What do you guys think, or recommend? Is it ok to drive until I get a new gasket or should I not even risk it?

Almost there!!!

03-31-2013, 02:11 PM
I would say you don't want your rocker arms banging into anything. I'm surprised that there would be so little clearance that a flattened gasket would allow the rocker arms to hit the cover. Are you sure you have the correct cover?

03-31-2013, 02:26 PM
It's certainly possible. However it looks, to me anyway, like the right kind. But I'm only comparing to pictures I've seen online. Maybe you guys can tell me:

03-31-2013, 02:36 PM
Are there matching shiny/worn spots on the cover? In that first shot, it seems odd that the nearby edge is angled/rounded, while the notch on the arm is square to the arm. Ok, that could be, but what would the other arms be hitting to make a notch? The cover doesn't have an edge in those areas.

03-31-2013, 02:59 PM
Randall, that's a good question. And where the filler cap is, there is definitely a notch underneath. I did look underneath the rest of the cover and didn't see anything suspicious anywhere else, though. Maybe I'll have to take a closer look after some cleaning and take more pictures. The valve cover is slight contoured in a way that it might produce edges. A different angle here:


03-31-2013, 03:05 PM
I just did a search on this forum and my valve cover looks exactly like Geo Hahn's in this thread: https://www.britishcarforum.com/bcf/showthread.php?82493-TR4-Upgraded-inlet-manifold-valve-cover-question

PS Randall, should I put on one of those vent filters that you and Richard mention there?

03-31-2013, 05:48 PM
Also, Scott, are you sure the notches haven't been there all along? If the rocker arms had been hitting something metal, hard enough to put such notches, I would think the racket would be very loud, indeed. Perhaps cleaning or other work there has uncovered what you never noticed before.

03-31-2013, 06:17 PM
Yeah, Ed, that's possible. I haven't had the car very long and I've had my attention in a lot of other places. It does make a quiet ticking noise, but it doesn't seem to me to be so bad as to make those notches. But the clearance is very small. Just thought I'd check and see if you guys thought so as well.

03-31-2013, 06:41 PM
Is the contact flange flat and square to the body of the cover? My gaskets were 1/4" thick new and everything cleared.

03-31-2013, 06:55 PM
I'm not seeing a problem from the pics. The notches on the rockers look like forging marks, and they are not shiny, which would indicate recent contact.

Just of note, if the cover nuts are too tight, it can bend the cover down. I had to bend mine back out when I restored it last year. Now I only put them a turn past contact (that's the purpose of the nylocks), to hold them with little torque).

03-31-2013, 07:11 PM
OK going back and looking at the underside of the cover I think I'm only partially correct in my worrying. Everything looks fine except for the flange where the filler cap goes. It's notched from contact (look at upper left portion):


And just going off of what you said, John, all the other rockers' notches look dark, but that one #8 rocker is shiny--you can kinda tell from that second photo (the rocker to the far left), but there's a little bit of a glare. I think I'll just file that lip down a bit and order a new gasket just for the heck of it.

03-31-2013, 07:53 PM
It's normal for it to make some noise, mechanical lifters always do. Seems like I always have one that is louder than the others, don't know why.

Cover looks right to me. Seems unlikely to me that the rockers are hitting the cover, but could be possible I guess. The marks in the underside of the cover should be really obvious, though. If you find them, I'd try gluing a second gasket to the first one, to put the cover higher.

Not sure what to say about adding a filter in place of the (sealed) cap. Probably not worth the effort if the engine is reasonably fresh; but not going to hurt anything either, if you can find something that will fit. It's a lot easier with the earlier covers, though, since they have a neck that the filter can just clamp onto.

Geo Hahn
03-31-2013, 08:51 PM
I just did a search on this forum and my valve cover looks exactly like Geo Hahn's...

Yes, though mine are not that close. There are some machining marks on the top of the rockers so maybe that is what you see on some of the others.

I just measured my spare (cork) valve cover gasket -- it is 3/16" thick. Some are thinner and all will squish when installed but a new one might help.

I find no need to have those nuts really tight if the head an cover are clean and Hylomar is on each side of the gasket.

If it is hitting -- I wonder if someone milled the head and then installed taller pedestals (or shims under the pedestals) to regain correct geometry?

Don Elliott
03-31-2013, 11:19 PM
Does the rocker or the top of that valve look higher than the others ? Maybe some PO installed a valve with a longer valve stem ?

04-01-2013, 12:09 AM
The PO did have the engine rebuilt so both of those suggestions are possible. But all the valves appear to be of similar height. If only the rearmost valve is hitting, then it's because of that small lip under the cap. In any case, there isn't much clearance for any of them.