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In response to a request last Thursday I have finally gotten access to
a Rockwell hardness tester and did a little testing on B20 lifters and
a cam. I only had one OEM cam to test, and also only two OEM lifters,
so this testing does not tell the whole story. The reason I feel that
way is that I am sure that there are plenty of great OEM lifters out there
but it only takes ONE defective one to mess you up. I don't know what the
proportion of good lifters to bad lifters might be, but having had 4 engines
wipe out because of what I conclude to be defective lifters, I continue to
be very reluctant to use them.
The OEM lifters are chilled iron. This is a white cast iron which is cast
in a mold with heat-conducting surfaces so that as the iron cools
from the casting temperature, the parts of the casting exposed to those
surfaces cool fast enough to make them very hard on the surface and somewhat
below the surface. I only tested two and it is obvious to me that both of
the lifters I tested were good. One of them I tested on the original wear
surface. It yielded a hardness reading of Rockewll C 54. I tested another
OEM lifter with about 0.030" ground off the wear surface, being careful to
keep the lifter cool while grinding. The hardness on that surface was
variable between Rockwell C 50 and 54. As would be expected, the interior
of a chilled casting cools at a slower rate than the surface and thus is
slightly softer. This is still a small, nearly insignificant difference.
I tested an "IPD" lifter, apparently manufactured by Sealed Power, who makes
a LOT of lifters for all kinds of engines. This one was made for a Chevy
V8 engine, I believe. Its hardness was Rockwell C 55. This tells us that
the Chevy lifter is MARGINALLY harder than the OEM lifter. Although I did
not have the opportunity to do any more tests than those cited above, one
obvious difference is that the Chevy lifter is made of steel and "through-
hardened". The only failure I have had with those lifters was a cam with
welded lobes, and the welded lobes were soft enough that I could easily file
them with a dull file. I sent the cam back to the vendor and they replaced
it for me, paid shipping,paid me for the gasket set I used, and would have
also paid me labor if I had asked them to. Incidentally I used the used Chevy
lifters with the replacement cam, which now has about 80,000 miles on it,
replacing the two that were on the defective lobes only.
I also tested a "D" cam (the only OEM cam I had available) for hardness.
I found the bearing journals are NOT hard (Rockwell C 21) but the one
good hardness reading I could get on a lobe indicated Rockwell C 52.
Assuming a correction for the curvature of the lobe of 2 points, the
cam lobe is about the same hardness as the OEM lifter.
I would like to have been able to test some of the OEM lifters that have
wiped out cams for me in the past, and my wife might express surprise that
I have not kept them ("Well, you keep everything ELSE!!"), however I got
a degree of satisfaction out of throwing them as far as I could, so I don't
have them any more and thus can't test them. I am pretty sure that those
tests would reveal a VERY hard surface at the outer periphery of the concave
worn surface and a much softer surface in the center. If anyone has some
damaged OEM lifters that they would like to send me I would be happy to
confirm or deny this theory. Meanwhile I will continue to use lifters
I trust.
Your patience in reading this far is appreciated!
--
George Downs, Bartlesville, Oklahoma, Central US
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