Hello everyone,

I only have about 150 miles on the car since rebuild and I’ve had to adjust the lash on the same valve at  5 or 6 times now. All of the others valves seem fine fine, but the lash on a valve on #6 constantly needs readjusting. I understand that the engine is still break-in stage, but I’m beginning to think something is wrong.

I initially set the lash up to be .019 on all valves, but am now going as tight as .018 on the problem valve and it still loosens up after an afternoon's drive.The lash on that same valve has grown to .024+ after only 20-30 miles of driving. Does anyone have hunches as to what’s going on? Do I have some kind of unusual wear problem with that rod, lifter and/or cam lobe? This does not seem normal to me. Or Is this normal while breaking in the engine and how often should I expect to redo the valve lash?

New parts:

cam

pushrods

valves

springs and retainers

rocker-arm shafts

 

Freshly Machined:

rocker arms

lifters – good old original ones

heads  - including hardened valve guides for unleaded gas.

 

I broke in the engine right after first start up by running it for approx. 20 min at 2500 RPM.

Try a new adjuster in the rocker.

Ed. Hopefully your cam is o.k.  Vicky is probably right about a defective adjuster, particularly if yours are the "interference fit " type rather than the "jamb nut" type. There is some history of problems with these in use.  Oversize thread (+.oo3 ?)  replacements used to be available. You could try J. Mummert or Rocker Arm Specialties if you can't get one in Canada. A temp fix might be to try Locktite. - Paul    

Paul

Hi guys,

Thanks for the tip. After a closer look I found that the ball on the adjuster was slowly being worn to a nub. So I just replaced it with a spare that I had on hand and all seems well now.

Off I go cruising...

Ed

Ed,



What color was that adjuster that failed, and where did you obtain it? I wonder if it was from the same bad batch (improperly hardened) that John Mummert complained of?

I recently installed a set of repro 56/57 style rockers with interference adjusters (black), but left off the jamb-nuts that were included. Though my lash has been pretty stable, I notice the adjustment torque on some of them has decreased quite a bit. If the thread surface has likely been improperly hardened, I guess I had better keep an eye on the ball-end also!

6 VOLTS/POS. GRD. NW INDIANA

The problem seems to be solved now. I drove the car quite a bit this weekend and no more ticking. Thanks Town Vicky and everyone.

 

As far as I’m aware the adjuster that failed was off the original engine – likely rebuilt back in late ‘70s. It wasn’t black. It does seem odd that that one is the only one that had that problem. I’m also going to also be keeping a closer eye all of them now.

 

Thanks again,

Ed