[William Miller]

Back to the project:
Last night I installed intake rockers #1 & #4
I set the basic timing on #1 and noticed that when I turned ir over by hand that I had some resistance. (Intake valve touching piston)
I adjusted the timing per the 930/10 specifications which is 1deg btdc. (dial the crank to TDC at 1mm valve lift.)

After I did this I felt no resistance. Turned smoothly and I could watch the dial indicator spin as the valve opened and closed.

I installed #4 rocker and timed it. I could not get it exactly to the spec because I could not get the hole and the sproket to line up perfectly. I ended up with this one a little advanced like 1.09mm lift at TDC. The other choice (next hole gave me slightly less than 1mm lift at tdc.)

Next I checked the valve to piston clearance. (Intake only so far)
#4 first since the dial gauge was there and I could watch it spin.
I adjusted the screw one turn (1mm) in past the point where it touched the valve stem. I turned the crank around several times. No resistance. Everything fine. I turned the screw in another 1/2 turn and felt resistance as I turned the crank (the valve was touching the top of the piston just before tdc because the valve starts to open before the piston starts to go down.)

I started to realize that the tolerances are in fact very tight. This is probably the cause for the marks in the tops of #1 &#4 pistons and which ultimately led to the ring breaking.

On #1 I did not encounter the resistance until I turned the screw in abou 13/4 turns or mm.

I began to wonder how the cam timing would effect this measurment.
I attempted to time both sides to 1deg or 1mm of lift. the right side ended up advanced slightly because of the hole and sprocket alignment. I decided to reset #4 (retard it to the next hole) This gave me just a hair under 1mm lift. It's really hard to tell because the pully is about 1/2" from the split in the case.

After this very small cam timing adjustment the piston to cylinder clearance went above 1.5mm as recommended by wayne.

I began to try and think "what's going on." I set the cam timing to the euro specs. the center of the range is 1mm to get you 1deg btdc.
I suspect if I set it to the US spec 7 deg btdc (center of range 1.55mm) I would have substantially less valve to piston clearance than the 1.5mm recommended in Wayne's book.

I'm beginning to wonder again if I have the euro cis pistons.
In the whole set up the main difference between the us an the euro version is 9.3:1 vs 9.8:1 compression.
Everything is equal except for the dome volume of the piston. Is there possibly less valve to piston clearance with the euro set up? Maybe that is one of the reasons they retarded the cam timing.

I guess the isue may also fall with the camshaft profile itself. The camshafts appear to be stock, but who knows.

In any case I have read a lot about the variations in valve timing. I mostly have read that there is some minor differences in where the torque is the highest.


I think for now I will leave it at the current setting where I know I have adequate valve to piston clearance.

I hope to install the exhaust side rockers and check the clearance on them they are supposed to be 2mm. I doubt there will be any problem.
Charlie, do you have any thoughts?