Piston to valve clearance is a very important measurement that must be performed in any engine build. In all my research I came across two different methods of doing this. The first is using a dial gauge set up on the valve spring retainer and checking at different intervals of crankshaft revolution how far the valve can be pushed down before contacting the piston (more on this farther down). The other method of checking is using clay, which I will explain. I did both checks, this is my first engine build so I figure better safe than sorry.
The degree wheel is used again for this check. I brought the piston to 20 degrees before top dead centre (BTDC) as my starting point.
I then pushed down on the lifter slowly watching the dial gauge until I felt the valve contact the piston. I recorded the reading from the gauge at this point. I then moved the crankshaft in the normal rotation (clockwise) to different degrees in the crankshaft rotation and did the same thing.
After I did the measurements for the intake valve I moved the setup over to the exhaust valve and did the same thing.
Below are the recordings that I got at each interval. It looks like the closest clearances seem to be about 8-10 degrees after top dead centre on the intake valve and 6-8 degrees before top dead centre. Minimum clearance on the intake valve should be 0.080" or more and for the exhaust side 0.100" or more. My numbers are well within safe limits.
Next I decided to see what clearance numbers I get using the clay method. I won't be needing to have the light weight checking springs on the number 1 valves anymore so I first swapped the regular springs back into the head.
Below I have my valve spring compressor set up.
The valve is compressed to insert the two valve retainers in
Below are the two valve spring retainers
Valve spring installed
To perform the clay method of checking piston to valve clearance the head gasket needs to be used also to get a accurate value.
A chunk of modeling clay was placed on the #1 piston, enough to cover the whole span of the piston where the intake and exhaust valves are.
The cylinder head was then placed on the block and just snugged down.
The valve train for the #1 cylinder are setup again. Once again using the lifters that I made into solid lifters. The engine was then turned over a few times, enough that the intake and exhaust valve open a couple times.
Everything is then taken off again. Below the intake and exhaust valve indentations in the clay can be seen.
Carefully using an x-acto knife I cut each indentation in half. I then used my calipers to measure each indentation at it's thinest points.
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