Valve to piston clearance

[nm9stheham]

Some people tear them apart and make a solid shim to hold the plunger in place to keep it from bleeding down and making your measurements incorrect...

If you could set the plunger at it's bottom and then set your adjustable rocker to zero lash it could work...

This is the accuracy issue with a stock pushrod length, fixed rocker gear, and a solid lifter or a 'made solid' hydraulic lifter: You have lost the .060" nominal compression of the hydraulic lifter. This means the valves will be hung open in the measurement and will be nominally .090" closer to the piston than when running with a hydraulic lifter in place....

Now.... if your clearance is adequate in this 'solid' setup, you are home free. When you put in a real hydraulic lifter, the running clearance will enlarge. But, if you use the solid lifter method with all other parts fixed, and you get inadequate piston to valve clearance, then you have to use some adjustable part somewhere, or measure how much the valves are 'hung open' as suggested: Put the lifters on the base circle of the cam and back off the rocker shafts, while measuring how much the valves move to the seated position.

 

[James Camp]

could you use a borescope with flexable end and camera, and go thru the plug to see the clearance between piston and valve ,turning engine by hand?

 

[nm9stheham]

But even if you could see it, how could you measure it? And that is assuming the 'scope was not pushed out or crushed.... the minimum P-V clearance is around TDC.

BTW, Robert.... were you at VA Tech in the late 70's or early 80's, or work at GE in Salem, or were in the US Naval Reserves in Roanoke? If this is your actual name, it suuuure seems miiiiiighty familiar. And did you trade a Celica GT for a Ford Econoline van?

 

[Bobzilla]

Post 24 has the most accurate way to check it. The tightest clearance usually occurs right at 10 degrees before top dead center for one lobe, and 10 degrees after top dead center on the other lobe. I forget which lobe is before and which is after, so check both lobes at both spots.
The only thing this method does not check is radial clearance, but that can be checked another way if the heads are not final torqued already.

 

[MOPAROFFICIAL]

Ive got KB flat top pistons with valve reliefs, EQ heads and 222/226@.050 roller cam.
I dont have solid lifters so I cant measure the clearance, because the hydraulic lifters just collapse. What do you think, should I be worried about the clearance?

I dont think you have anything to worry about.

I did a 360 kb373 quench head w/ .585 hyd roller ... no clearance issues.