The s***** machine shop you got for your "valve job" sank the valve\valves too deep into the seats, thereby reducing your available adjustment up top. This is common with tobacco-drooling good 'ol boys that work on Fords or Shivelays and have never "heerd" of an overhead cam. Since you probably don't want to pay for new seats or valves, I would go with a set of the available .015 " cam tower shims. Others may correct me, but I believe they are still available thru a place called "Goodsons". Do not grind the valve stems for clearance (the keepers will hit the lash pads, causing the tips to separate) Do not attempt to grind the lash pads, as they are "dimpled" on the bottom.

To remove rocker and lash pad, rotate engine until cam lobe points away from the rocker (up). Using the cam as a fulcrum, pry the valve retainer down with a large screwdriver enough so that the rocker can be removed. Then remove the lash pad.

BTW the head won't flow as well as it should with sunken valves, so seriously consider pulling the head and finding a decent machine shop that knows what they're doing......

 

I like you Doc Z with the only information you have is the head was sent to the machine shop and now one valve wont adjut some one has to have s***** for brains. You should change your name to the Z god. Maybe there has been a slow leak on #6 and seat was ground until usable I can think of many reasons, but to just label someone as incompetent when not knowing all of the facts only shows your own ignorance.



Post Edited (Jun 1, 5:31pm)

 

Ouch !

That was almost painful to read. I kinda like the guy that did my head and overall I think he did a good job. He did the P79 shave and shim already,
raising the cam towers with the Goodson shims. When I came to pick it up he did say one valve gave him a hard time and to see how it ultimately worked out after I ran the engine a bit.

The only problem was just that one tight exhaust valve. I'm tempted to run it as is. There is <<some>> clearance 0.006 instead of 0.012 - just about halfway there. Not tragic, but not 100% either.

The lash pad does seem a good way to go. Perhaps I could just purchase a thinner one instead of machining the existing one down?

Still pondering the situation

 

Although my delivery just might be a little bit kinder than the above, I am however in agreement....This was a dipstick mistake done by the machine shop who did this work.

This is Basic Machining 101 type stuff!

I'm recommend that you don't take any other work there at all, even just to correct this gross error, as they should. But if they pulled such a bonehead mistake as sinking the valves and/or not "topping" the stems correctly AND/OR!! not equalizing and "centering" the shims....I would not trust them to correct those errors!!!

But IF!!! this happened because the choice you made as to which machine-shop to use was based solely on trying to find the lowest price...You deserve this!!!

G.O.B. network be damned...I take serious and personal pride in my machine-work! Far too much pride to let crappy work like this even leave the shop! I wouldn't let it happen...Period! Even if I had to loose a few bucks!

"The bitterness of poor quality is remembered...Long after the sweetness of low price is forgotten!"

You almost ALWAYS! get what you pay for...One way or another!

....ase mat

 

Hi ase mat,

Thanks for the note. Yeah, I can not quite figure it out since all the other valves are correct. Why would just one be too tight?

I did shop around for a machinist with a good reputation. This fellow actually does alot of fancy work on the new Nissan/Accura/Mitsubishi heads. He showed me the kind of work he does and it
all looked great. I explained what needed to be done to the P-79 (tower shims, shaving the bottom off the head, etc) and he said it was actually a straight forward job. He adjusted the heights of the valve stems, etc and even did the math to make sure that the final compression was not going to be too high - just under 10. Maybe there was a defect in the head or some other problem he was working around?

Anyway - I'm still perplexed what to do.
1) Run it as-is and hope the valve does not burn
2) Cut the lash pad down and re-machine the dimple back in. Maybe I could buy a thinner lash pad?
3) Pull the head (ugh), buy another exhaust valve and try again.

 

Mr. Yurmohill: Wipe your chin boy, you got some bacci juice dripping.
(I really am a Z God, but I use the name Z Doctor so as not to overwhelm)

 

Getting good info around here is like pulling teeth sometimes. People get so stuck on what "they know" that they don't even see the real question much less answer it.

Yes you can buy a thinner lash pad, try malvern racing, they come in pretty much any thickness. Cheap and easy to change.

Don't run the valve too tight it will just cause more problems then the head will be useless.

The head probably already had a sunken valve due to someone overtightening it previously.

Matt

 

The stock lash pad is the thinnest. All the others available for reground cams are too thick. The earliest L16 engines (1960s) had an extremely thin pad with no dimples, but finding one of those is next to impossible.

You're still better off fixing the underlying problem rather than half-assing it.

 

If the valve lash will not come into spec, there is a problem. Find it, and fix it before it ends up destroying something else. Maybe you are the lucky one, and all will be ok.......maybe not.

If anything, that valve will get tighter with age. Either the valve will sink in the seat more, further reducing valve lash. Or the valve could stretch, further reducing valve lash. Or both! Either way, it's not going to get better.

 

Sorry for all the name calling, has nothing to do with your problem. Machinest put you on notice of problem,he is teething on edge of doing what is right. I really think you should tell him this is not what you paid for if he corrects the problem keep him for life, if not ditch and go to some one else. Maybe wrong but calling him a s***head right off bat will get you no where.



Post Edited (Jun 2, 5:03pm)

 

Hey, after you get screwed with this problem a half dozen or dozen times, it's hard to show restraint. Seems there are people hanging out a "machinist" shingle and practicing machinism without a license pretty much everywhere.
Let's call a spade a spade and move on. PS: I can call this machinist any name I want to.....he ain't working for me. Besides, I didn't refer to anyone personally as a S***head, but rather the machine shop as being s*****.