Author Topic: cam end play  (Read 5565 times)

Offline hotrod316

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cam end play
« on: January 23, 2015, 12:50:02 PM »
Matt,
 on a solid lifter cam should you still set the end play on the cam, between hex drive and the pump.
if so, how much end play and is this with the gasket or no gasket?
or does this screw up the lifters from spinning and pushing the cam back?
going to use a thrust bearing and shims
hope this make scene  to you
always thanks for your time
steve m
 
 

Offline Frontenginedragsters

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Re: cam end play
« Reply #1 on: January 23, 2015, 07:23:11 PM »
Steve:
 Yes you should always control end play even with a solid flat tappet camshaft.
It could be said that its more important than on a roller. In My Opinion.  ;)
Assuming its on a Chevy right?? What brand of engine in the old days had more OEM camshaft failure than any other?
If you said Chevrolet than your Right!!! ::) ::)
The engines that do not use a thrust plate to control camshaft movement relied on the helical cut gears on the distributor
drive to pull the camshaft to the rear of the engine during acceleration. 
This keeps the camshaft lobes in one spot and the wear pattern on the bottom of the lifter happy.
The camshaft lobes are not flat. They are ground at a slight tapper. The lifters are also not flat. They are spinning when being ground and have a slight crown in the center. The high edge of the cam lobe rides on the outer edge of the lifter causing the lifter to spin in the bore.
The tension on a good tight timing chain set keeps the camshaft from moving forward when you let off the gas pedal and life is good under the timing cover.
Now your 1974 Impala has 67,000 miles on it and the nylon teeth on the top gear are all in the oil pan and that timing chain
is about ready to jump a tooth. Your cruising along with the 8-track playing Chech and Chong and de-accelerate for a stop sign coming up. That camshaft is chucking as far forward as that loose chain will let it, sometimes the only thing stopping the cam from falling out is the 3 cam bolts grinding into the timing cover. Now the lobes of the camshaft are moving forward and backward 3/8" of an inch. The camshaft can not make the lifters spin anymore. Now your cam and lifters are done. >:(
 Long story short.......
    Control the end play on the camshaft and you will not only see better cam life but your ignition timing will be a lot steadier.

Matt

P.S. Camshaft end play should be limited to about .010 to ..020 in a perfect world.
« Last Edit: January 24, 2015, 05:12:19 AM by Frontenginedragsters »
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Offline hotrod316

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Re: cam end play
« Reply #2 on: January 24, 2015, 10:02:01 AM »
Matt,
 great minds think alike 8)

AGAIN THANK YOU FOR YOUR TIME
steve morgan

Offline alkyal

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Re: cam end play
« Reply #3 on: January 31, 2015, 01:47:13 PM »
FYI the lobes on a mech flat and hyd flat tappet are ground on a slight taper. Approx. .0025 when new. The flat lifters are ground on an approx 32 in Radius.On a V-8 8 lobes are ground with the taper in one direction and the othere 8 are taper ground in the opposite direction to help offset cam walk forward or rearward. There is also as problem with lifter bores being 90 degs to the cam C/L forward to rearward. [note: Isky has a way to garage test your block-see their web site] With a Roller cam, Lifters being out of Square front to rear will cause EDGE RIDING of the roller wheel and bearing failures in the roller lifter. Lifter bore missalignment ONLY from left to right as viewed from the front or rear of the block will cause cam timing issues [ie when degreeing the cam per the card. I do #1 and #6 as TDC should be the same for both cyls]  The interface action between the tapered lobes and the spherical lifter bottoms causes the lifters to spin in their bores when unloaded. This action prevents the lifters and lobes from contact in the SAME pattern. The non-additive oils [mandated by EPA to keep the Cat Conv Operating] has caused most of the Wipe-outs. The current OEM Roller cams and lifters dont require these additives[ However most quality Race ONLY oils contain These Additives in a much High PPM than ever in the older oils/ These additives also help with Ring breakin and engine life]. As to End-Play on Racing roller cams-YES it must be controlled. I try to hold to .005 with a roller type thrust brg. Sprockets with no Brg. running against the block face can use .008 max. A little trick is to scrape a Tiny groove from the #1 CAM bearing feed hole [in the babbit] to the front end of the #1 cam brg., so as to lube the sprocket/block face area. Hope this helps you Al