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Re: Adding new shims to set valve lash for 78' 99 turbo  1 Saabers Like This Post!
Posted by Gary Stottler [Email]  (#1463) [Profile/Gallery]
(more from Gary Stottler) on Thu, 15 Jan 2015 05:38:40
In Reply to: Adding new shims to set valve lash for 78' 99 turbo, Justin, Thu, 15 Jan 2015 01:15:16 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hi Justin,
I am going from memory (danger!) here, but if you are using stock settings I recall that the intake setting clearance should be .010-.012" and exhaust should be .016-.018. Especially for exhaust it does not hurt to let them go up to .020, but otherwise larger clearances just add noise and cut airflow.
Basically, if your measured clearance is below the spec, then you need a thinner shim which will make the clearance larger, or if it is above spec then you need a thicker shim.
So, on your engine, for example, your #4 exhaust measurement is .006" (dangerously low!) and you want to set it to .018", so you need a shim that is .012" thinner than your current one. I think you had one, (maybe #2 exhaust?) that you measured at .024" and you want it set to .018, so you need a shim that is .006 thicker than the current one.
In summary, if the clearance is too small, then you subract the difference, if it is too large you add the difference.
I always do both my clearance and shim thickness measurements in inches so that I don't get confused, but you could also use metric, but I hate to mix them or I get into trouble.
A caution on your #4 exhaust - I have seen a lot of engines with worn valve seats on #4 exhaust leading to burned valves and stretched valve stems even to the point of the head breaking off the valve, so you will want to monitor that one very carefully to make sure it is not continuing to wear quickly. I would check compression frequently as well.
A general issue with valve adjustments on the early Turbo engines is that you may find that you have a clearance that's too small, but you already have the thinnest available shim in there. While some folks (including myself) have ground shims thinner than those originally available, this "no thinner shim available" situation is basically your indication that you need to pull the cylinder head off and do a complete valve job with new valve seats, 'cause the old ones are worn out!
I can give you chapter and verse on what's needed to do a good valve job if you get to that point, just let me know.
I hope that helps!
Gary
_______________________________________ Gary Stottler
, Thu, 15 Jan 2015 05:38:40 <-- Viewing This Message
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