Valve clearance tolerance
Duncan
I'm in the middle of doing my first major service by myself. This is the
first time I've done this so I would appreciate a spot of help.
I've just measured the valve clearances and I got the following results:
Max inlet clearance: 0.19 mm (0.00748 inch)
My first test was trying 0.0075 (0.005 + 0.0025 blades) with the assumption
that if they went through the gap was too big.
The blades fit fairly comfortably in all the gaps.
Next I tried a single 0.008 blade and this did not fit any of the gaps.
With a bit of a push it would but I guessed as it did not slide back out
easily it was too big for the gap.
My question is, seeing as all ther gaps were the same and it is fairly close
to the upper clearance limit, should I replace all the shims or just let it
go for now?
The exhaust gaps fell fairly comfortably in spec.
Cheers,
Duncan.
Kaybearjr
>Max inlet clearance: 0.19 mm (0.00748 inch)
>My first test was trying 0.0075 (0.005 + 0.0025 blades) with the assumption
that if they went through the gap was too big.
I wouldn't worry about clearances to four decimal places,
a 7-thousandths feeler gauge and an 8-thousanths feeler gauge will work fine as
GO/NO-GO gauges...
If the 7-thousandths blade is loose and the 8-thousandths blade feels tight, I
go on to the next valve...
When the 7-thousandths blade feels tight, then I have to think about
re-shimming...
>Next I tried a single 0.008 blade and this did not fit any of the gaps. With a
bit of a push it would but I guessed as it did not slide back out easily it was
too big for the gap.
The correct "feel" of a blade between the valve and rocker arm or tappet has
been compared to the feel of pulling a business card out of a telephone book...
It shouldn't require much force at all to pull the blade through the gap...
>My question is, seeing as all ther gaps were the same and it is fairly close
to the upper clearance limit, should I replace all the shims or just let it go
for now?
I wouldn't worry about valves that might be about 1/4 of a thousandth of an
inch loose, or even valves that are 1/2 a thousandth of an inch loose...
The valves and valve seats will erode over a long period of time, and excess
clearance will disappear...
As the valves sink into the head, I would think about re-shimming any valve
that was 1 thousandth of an inch
tighter than the minimum specified clearance...
So, when 6-thousandths feels tight, the cams are going to come out of the
head...