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Old 04-25-2013, 12:56 AM
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simps80 simps80 is offline
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Join Date: Jan 2009
Location: Arvada, CO
Posts: 1,540

I do have a problem that I would like input on though.

the pistons are all stamped ra2648 .075 then 0.04 UD

.075 converts from MM to .0295 inches so I'm assuming this is .30 over...searching on mud reveals that's true:

but I can't figure out 0.04 UD.

I care because number 3 has a gouge the radius of which matches the intake valve:

Name:  no_3_piston.jpg
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so...I wonder if these are .04 "under height" to allow for block and head decking.

I would assume so, which then makes me ask why #3 got smacked..

so do you concur this is the valve contacting the piston? I think that's the only logical explanation for this shape and location, I should have taken a picture with the camera orientated square so the location of the mark was more clear, but it lines up with the intake valve.

for it to be one valve to piston, my likely flawed logic rules out too much milling of the head or block or other causes like timing that should affect more than one hole.

so ... floated valves and one kissed the piston?

its not deep, can catch your finger nail on it just barely is all ...
the cylinder walls are pure,
I think I'll continue with original plan and have the head reworked, I'll check the block for warpage, then turn it over and look at the bottom end before deciding on anything for certain especially since its already been rebuilt at least once it would appear.

thoughts on that approach?
Mike | KØSMP |
1997 fzj80 | 1976 FJ40 | 1965 FJ45lpb | TLCA # 20038
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