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Valve Adjustment?

9K views 4 replies 4 participants last post by  emsvitil 
#1 ·
I will be doing the timing belt on my Zetec within the next week or two. My question is : Do I or should I adjust the valves while I am in there? The car has just turned 145,000 miles. I was just curious if they need to be adjusted, bc I have never really seen anyone talk about it on this forum.
 
#2 ·
To some extent, yes.
Most don't talk about it because it's an involved process. It's a mechanical system and you have to replace lifters with a thicker/thinner lifter. If you don't have spares it's kinda fruitless as you'll be down until you have the correct sizes in hand.

But on on interesting note, I've also never seen anyone talk about how shimming tighter can increase stock duration, which it does. but there are diminishing returns on this and you have to know what you're doing.

For the most part, you shouldn't need to adjust them. Doesn't hurt to check though.
 
#3 ·
Thanks for the input. I was just curious bc when we pulled the head off my Cummins a couple months ago, that was one thing we checked was valve adjustment/lash. I wasnt sure about these engines though.
 
#4 ·
These wear so slow no need. The valve springs are weak enough to use in ball point pens. If motor runs fairly quiet and no lifter tick don't touch them. This type valvetrain wears so slow that often the clearance DECREASES from the exhaust valve wear at seat, or, the reverse of what most do or loosen with age. You won't know about too tight until valve burns, one reason why Ford spec clearance is so wide. When setting up one after valve job I set to the loose side rather than tight, the engine runs longer that way. In most cases though I think the normal wear (looser) is balanced out by valve recession (tighter) to run practically forever.

If you grind valves you have to re-set them up.

Shimming tighter could help add duration, but if running stronger valve springs can be a danger. On bikes with this exact same top end setup, you got into problems with running valve clearance not being what was measured. The cams would get pushed around in the cap clearances by springs to make actual running clearance different from what you measured. You could have up to .004" clearance and measure 6 times and motor would be down on power because of cylinder leaking from valve held open at actual running. Another reason why they run a looser spec.

If you had the Contour zetec (pre'99?) buckets with shims you changed shim instead, you could grind a notch in tappet edge and pry the shim out to change without pulling cams.
 
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