Just got back in from claying the motor. Came up with some interesting results. But first, I realized that yesterday I did not have my exhaust rocker assembly properly lashed. I used a new rocker assembly on the exhaust side. Therefore, I repeated the v2v measurements.

This time the v2v clearance was more in line with what I expected. This was at .010" lash. Quite a different result from last night.

Just for kicks, I checked the v2v at .011" lash. .001" of lash gained .002" of clearance.

Now, on to the claying. The process is very simple, cut out strips of clay, and lay it out on your piston in the following areas. Lock your rockers in VTEC and set your cams to the max settings you think you can get away with. Then assemble the head to the motor. Some people will spray down the combustion chamber roof with WD40 to keep the clay from sticking to the head, but I've found that it's a crapshoot on whether the clay will stick to the piston or the head no matter how much WD you spray on.

Once the head is on the motor, turn the engine over so that the valves make their impression on the clay. Then take it apart to inspect. As you can see below, there is plenty of clearance between the piston domes and the head. The exhaust v2p measured out to .125". I didn't even need to measure to know that the intake v2p is insufficient. The intake v2p measured out to .015". This is one reason why you use old valves when claying a motor. If things do touch, you don't want to trash a new valve.


The conclusion is that the Skunk2 stage II cams are NOT 50deg safe in my motor. I always suspected this. Back when I did the cam test, the skunk2 stage II's (and the IPS k2's) had an insane knock count anytime I'd advance to 50deg on the VTEC lobe, no matter what rpm. My suspicions that I'd have clearance issues at 50deg were cemented when the v2v clearances came up so small with the exhaust rocker lashed correctly. For reference, I have shelf stock CP 12.5:1 pistons with Eagle rods.

One curious note regarding my engine is that TDC occurs well before the factory mark on the crank pulley and cam gears. I've long suspected this, but was able to verify it with a travel gauge. Finding the true TDC point of your motor is a simple affair with the head off and a travel gauge. You setup the gauge perpendicular to the piston and turn the crank while watching the gauge. When the needle reverses directions, you've found your TDC. You can do the same thing with the head on the car, but you'll need a long extension for your travel gauge.


Typically, knowing the "true" TDC of the motor is not necessary, but in my case, I'm degreeing the cams in so I need to know exactly where my TDC occurs. Once I know where TDC is, I can set my exhaust cam centerline accordingly. Oh, and to degree cams, you need to be able to measure the angular travel of the crank. So I made this little thing.


The goal is to have my cams precisely dialed in relative to my "true" TDC. But that will be saved for another post.