Thanks to those who have sent me suggestions on troubleshooting my valve
train problems on my big block chuby. I have not yet completed the
diagnostic workup so there is more to come. However, I might add that the
usual issues such as valve to piston clearance, spring bind, correct pushrod
length for geometry are things I did when I assembled the motor. I have no
reason to suspect a change, other than abnormally worn or broken part. And
the motor has given me about 1500 miles of good use with numerous high rpm
spins
(after a lengthy break in period.)
Now, the good doctor has found some new clues:
1. When I first pulled off the valve cover I
smelled the inside of the cover. I didn't like the smell.
2. As I was looking at the valve train I noticed
that the rocker that was completely off and the two that were either loose or
had bent pushrods had nuts that were a different color than the rest.
I used the nuts that came with the Competition Cams stamped steel roller
rockers. They are kind of a anodized gold color. But those that had
a problem were black.
3. Upon further inspection of the problem rockers I
noticed there was a lot of black carbon deposit on the outside lower part of
the
rocker, around the area that the pivot ball is located. I was surprised to
see carbon deposits on an engine that has so few miles on it.
4. Inspection of the pivot balls show galling and
even discoloration of the matting surface of one rocker. It almost
looks blue.
5. Oil up through the pushrods is not the
problem. The last time I played with the lash while the engine was running
and the covers were off it looked like I just dumped a quart of oil all over
the
engine compartment. I had to stop because the smoke was too thick to see
through. Even with the clips on the rockers. And, I did check each
and every rocker to make sure it was getting oil.
By now the pieces of the puzzle were falling into place and I already
suspected the source of the problem but I had to call Comp Cams and run it
by them anyway. After I explained the symptoms and my observations the
first question the guy asked me was "Are you running tall valve covers?"
When I bought the engine it had on a set of chrome Edelbrock valve
covers that are just a bit over stock height. That is what I
still run. They're real purdy lookin! But sure enough, a closer look
underneath reveals the lack of a drip rail.
I agree with the Comp Cams guy when he says there isn't a problem
at low speed but at continues high speed, the oil isn't flowing into the rocker
cup but is getting flung off onto the cover and is running across the top and
down the side. The springs are probably getting lots of oil but the pivot
ball is not getting enough at high rpm. At least it's obvious that the
rockers are not getting enough oil. And I don't think it's the fault of
that Melling high volume pump. I don't use restrictor plugs as I would
rather pump more oil for a few HP than have happen what is happening.
Anyone have a set of valve covers for sale? I
do!
--- Gene Halvorson
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