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Va914's Avatar
 
Join Date: Aug 2000
Location: Williamsburg, VA
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Piston and Valve Clearance

Okay I am following Wayne's book's and have a Q or two.

First off the Cam timing is a B!&C#, but it's done.

I like the way it was worded in the 101 better then the other book Wayne

I am now at the point of checking the valve-piston clearance. I have a stock 2.2T that has had the heads resurfaced some.

I just want to make sure this isn't a process that is needed on the bigger more aggressive engines? If this is not needed on the smaller HP engines then please speak up.

So far so good.

Kerry
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Old 05-09-2005, 05:08 PM
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Only thing extra checking costs is your time. If you don't at least check it you could ruin all your past hard work and parts which are valuable and cost $$$$
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Old 05-10-2005, 04:44 PM
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Checking the valve-to-piston clearance is an operation best done before timing the cams (and rotating the crank). I would have suggested using clay or solder on the piston crown and light springs to close and open the valves.

At this point, you'd have to regress a little to perform the above. However, if your engine is factory spec with relatively low HP, it would be safe to just verify the cam timing is spot on, rotate the crank to make sure it rotates okay, then proceed. Still, checking is verifying so there's nothing to assume.

Checking the clearance is mandatory on any modified engine.

Sherwood
Old 05-11-2005, 12:44 PM
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I check the piston to valve clearance with the cams timed but just #1 and #4 intake and exhaust valves in place. Backoff the valves that you aren't measuring (i.e. the other 3 valves).

Sherman, Are you thinking of piston to head clearance perhaps?
-Chris
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Old 05-11-2005, 03:58 PM
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Chris,
No. I meant valve-to-piston clearance. The piston-to-head clearance is another issue.

If you check the valve/piston clearance after timing the cams and it's okay, you're fine.

However, let's assume the clearance is insufficient. The top end now has to come off and the pistons machined or whatever it takes to restore adequate clearance. Timing the cams and using up the head and cyl. base gaskets then was just an exercise that you'll end up repeating. Make sense?

Sherwood
Old 05-11-2005, 05:44 PM
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My thinking (and I've been wrong. sigh, a lot) is this:
The valve to piston clearance is a function of the cam lift and cam timing. Without the cam timing set I don't have a good way to check it.
(The closest the valves get to touching the piston isn't at TDC.)

The VtoP clearance check I'm talking about is the turn-the-adjuster-screw-and- count-the-turns method.

I'm just tired and a little dense right now so cut me some slack if I'm not "getting it".

-Chris
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Old 05-11-2005, 06:58 PM
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