Most times when I work on this car I discover how much I have yet to
learn about it and cars in general - mostly this is fun . . . and
another way of saying I feel like I ask a lot of questions as a result
of basic ignorance! Anyway, you might recall that I posted about a
"dropped" valve guide the other day (intake) - it had moved into the
intake passage at least .20". Stem to guide clearances seem to be in
line, and the interference fit mic'ed out correctly.
I picked up a few replacement guides and noticed that the lengths of
what I purchased and what installed vary considerably.
Installed - 2.07" (both intake and exhaust) - this means the intakes
protrude more above the head and more into the port.
the odd one that dropped - 2.16"
New ones from a reputable source - either 2.03" or 2.27". I would
assume the longer ones are the exhaust, given the head configuration,
but would love to have someone confirm that.
Available travel before the retainer hits the top of the guide - 0.58"
Gross valve lift with current rockers - 0.490"
Net valve lift after clearance - 0.475"
OK, so the extra length may be why the odd intake guide moved, though
it moved a lot more than the extra protrusion would indicate.
BTW, the factory manual says the valve guides are supposed to be 2.72"
long! Don't know how they fit, unless they protruded halfway into the
air passages, and of course the valve lift was less.
So, the questions are -
1. which is supposed to be the longer guide - the intake or exhaust?
2. how much clearance is enough between keeper and guide top?
3. how much should the guide protrude into the air passage? In the
current installation, the intakes protrude about 0.2-.25", and the
exhaust not at all.
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fot@autox.team.net
http://www.fot-racing.com
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