This was a discussion on a bent push rod that I found on my number 1
push rod. After Bob's reply I examined my pistons more closely and
found a ding on the third piston. The push rods for the third
combustion chamber are dead straight and the old valves show no sign of
impact.
I have replaced the head entirely with a new AL head with new valves
and springs. I am replacing the bent push rod which showed no unusual
wear on its tip. My current thoughts are that the damage to the third
piston dish occurred some time in the past with a different set of
valves a DPO or few in the past
I read in haynes how to decarbonize the pistons and plan to do that.
When the replacement head and all off the other goodies I have
purchased this time around I don't have the $ to replace the
pistons/rings and rebuild the lower half of the engine. IIRC a point
or ridge on a piston can heat and cause premature combustion which I
never detected in the past or possibly dieseling. Am I missing some
other problem that this might cause in the next year or so till I can
redo the bottom of the engine?
I also noticed that the old exhaust valves on the third and forth
cylinder is a very different color than the other 8 valves, it is a
reddish brown, the others are mostly black. I did have a problem with
a sticking choke on the front carb, so it this would indicate too rich
of a mixture on the first 2 cylinders that might explain it.. I have
never had a head off before, is this an indication of a burnt valve?
Since I put a new head on with new valves I haven't taken the old ones
apart to examine them yet, though I might it I get curious.
On Tue, 4 Jan 2000 13:25:00 -0500, Bob Howard wrote:
>Andy,
> Pushrod can be replaced individually. No need for a new tappet unless
>you see some peculiar wear pattern on the pushrod's round end. The
>tappets must always be replaced when a new cam is installed, as the
>tappets and cams are (supposed to be) machined to work with each other.
>Crane Cams has an interesting website, if you want to read up on this.
> Why would one bend? Check that the valve springs are not binding, that
>the valve is free to push down per the specs. An odd spring can compress
>to its limit, which could be less than the push of the camshaft, hence a
>bent pushrod. Do you see any marks on the piston? It's not likely that
>one valve would hit and not three others.
>Bob
Andrew Lundgren
Lundgren@iname.com
http://www.itwest.net/~lundgren
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