Small Journals and Camshaft Wear:

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Small Journals and Camshaft Wear:

Postby h-bot » Sat May 27, 2000 9:44 pm

From: twelve_second_vega_REMOVE_194726_THIS_@yahoo.com


GM claimed the "Squirt Holes" in the Small
Journal rod was put there to lubricate the piston skirts
and was later found unneccessary, being dropped with
the introduction of Large Journal Motors. As we all
know, the SBC is harder on camshaft lobes than some
other engines. I have discovered, over years of tearing
motors apart in the wrecking yards, that less cam lobe
wear is found in Small Journal engines. I supplied oil
pressure to an assembled Small Journal 327 with the pan
off, a controlled experiment. I discovered the "Squirt
Holes" also spray directly on the camshaft and lifters.
Not the best thing for windage, but an important
consideration, I think, for a street motor. As a result, I add
the holes to the Bearings and Rods in my Large
Journal buildups...Robert


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Small Journals and Camshaft Wear:

Postby h-bot » Tue May 30, 2000 6:42 am

From: mich_southpaw46_REMOVE_245790_THIS_@yahoo.com


Robert,
I think you are correct. Gee, this
happened at just the same time that GM had some "SOFT"
cams. I had always thought that the squirters were for
the cam, and your experiment finally proves it. I
think that the squirters added another step to the rod
building process, and that is why GM stopped doing it. I'm
not that familiar with other makes of engines. Do
they have squirters???
Or did they rely on the drip
method???

Robert, since you have a lot of experience rebuilding
engines, have you noticed where most of the cam wear is???
I find that the front lobes on some engines are
worn more. If an engine is run low on oil (read low
oil pressure) for an extended period of time, the
front of the motor doesn't get oiled enough because it
is the last area to receive it. What do you
think???

Mike


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Small Journals and Camshaft Wear:

Postby h-bot » Tue May 30, 2000 10:23 pm

From: twelve_second_vega_REMOVE_309825_THIS_@yahoo.com


Mike,
Generally, I tend to see more wear on
the exhaust lobes. This is probably due to heat
transfer through the valvetrain. If you notice, there are
1/4" drainback holes in the block directly above the
camshaft. I don't believe they were put there to aid in
camshaft oiling, but here is what I did for a low
rpm/endurance application. My business at the time was building
racing engines, period. But, I once built a dozen 350
Chevrolet's for a Farming Company to be used in their Wind
Machines. Seems like they couldn't keep camsahfts/valves in
these engines and everyone in the area had built
engines for them. As they were goverened to 3000 rpm, I
decided to take a special approach. First, I used
Iskenderian's 262 Hydraulic Camshafts (good material as opposed
to "regrinds") and stock lifters with stock springs.
Then, I drilled the 1/4" drainback holes in the block
to 7/16" with a steep bevel and plugged the holes in
the front and rear of the lifter valley, forcing all
the oil to drain back over the camshaft. I installed
Big Block Chevrolet Oil Pumps with GM "Z-28" relief
springs to give 80 psi @ 3000 rpm using Valvoline 20/50
oil. Oil and filters were changed @ 750 hour intervals
and most of the 12 now have over 5000 hours. Only one
ever broke....and that was the (cast) crankshaft. With
over 2000 hours on the clock, the cam/lifters looked
brand new and were reinstalled. On the topic of
camshaft oiling, I am not aware of any "cam-in-block"
engine that uses "forced" camshaft oiling...Robert


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Small Journals and Camshaft Wear:

Postby h-bot » Wed May 31, 2000 12:23 am

From: denisst78_REMOVE_145819_THIS_@yahoo.com


Robert,
while on the subject i know two

way to force oil to the cam lobes
1st; CROWER
sells gundrilled camshafts
(each lobes has a small
hole in it to spray
oil right at the bottom of the
lifter)
COMP CAM sells a lifter bore grooving tool

(simple to use when you rebuilt the engine,
just slip
the tool from the bottom of the
block then pull
the handle,it will make a
small groove in the
lifter bore,this will
also spray more oil on the
lobes)

Side note,
most engine shop don`t check
connecting
rod side play, if it`s too tight then you`ll

have much less oil spray

Other causes for
lobe wear,
Cheap oil filter,
low oil
level,
oil wasn`t changed a lot,
Bypass in the oil
filter adaptor
(where you screw the oil filter)

let oil bypass the filter
(easy trick, remove the
plastic valve and
the spring and plug the hole whit a
1/4
pipe plug)
dirt in the engine
(abrasive)
(intake manifold was just changed and particules
of sand,sand paper,dirt falled on the cam then the
lifer just grinded their way in the lobes)
Valves
clearances too tight on a solid lifter
cam (please don`t
use a rev kit on a street roller cam
too!)


Denis


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Small Journals and Camshaft Wear:

Postby h-bot » Wed May 31, 2000 12:25 am

From: denisst78_REMOVE_554075_THIS_@yahoo.com


BTW,
just changed a cam in a 1980 Z-28

last week
intake lobe on the number 1 cyl was
round,
changing acam in a 1972 Vette this week

exaust lobe on the number 6 cyl is round



Denis


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Small Journals and Camshaft Wear:

Postby h-bot » Wed May 31, 2000 5:50 pm

From: twelve_second_vega_REMOVE_498961_THIS_@yahoo.com


Dennis mentioned some very important things. Rod
Side Clearence is very important too. I keep it really
tight on street engines and run about .022" on a steel
rod race motor. Just a thought or two on the
subject...Robert


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Small Journals and Camshaft Wear:

Postby h-bot » Fri Jun 02, 2000 12:29 pm

From: denisst78_REMOVE_612710_THIS_@yahoo.com


Just another tought on camshaft

subject,
When you run a long duration High lift cam
you
need to run Heavier valve springs
(more
pressure)
This will contribute to wear the camshaft a bit
faster
So if your car is running heavy spring then
try
to not let the engine idle for too long...
When
the rpm is low the cam doesn`t see much oil
so
keeping the rpm faster(don`t let the car heat up at idle)
will aid in oiling the camshaft

Denis


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