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Discussion Starter #1
I have an early block that I am putting a roller cam in. I got a Cloyes cover with an adjustable cam button. Is a thrust washer necessary behind the cam gear?

A flat tappet cam pushes the cam backwards. A cam button on a roller cam keeps the cam from walking forward. Do you have to worry about it moving backward?
 

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I have the same set up , its called retro roller cam. I use the cloyes hex adjust gear and cover with the adjustable button. The hex adjust gear has a encapsated torrington bearing to run on behind the gear. You need this bearing as its part of the set. The bearing is what carries the load against the block. You did not say what timing gear set you had. I believe the part # of the Cloyes timing set you need is 9-3100A. See attached link
http://www.cloyes.com/images/CloyesHighPerformCat-2002.pdf
You could use other gear sets that require a wear washer but be careful in applying excessive pressure to the cover bearing. Usually required to be at finger tight .0 clearance.
 

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Discussion Starter #3
Right now I have an Edelbrock true roller timing chain. It is not machined for a thrust bearing. So in order to add a thrust bearing, I would have to either machine the cam gear or get another timing chain that has a thrust bearing. But, is it necessary to do? Is the Cloyes cam button enough? The button obviously keeps the cam from walking forward, but with proper endplay set up, will I need to use a thrust bearing to keep it from wearing the block and moving back?
 

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Due to the lobe bevel, Flat Tappet Lifters keep the cam centered and prevent walking. All Chevys will walk a Roller Cam forward due to the angle at which the lifter bores are machined.

To set up a Roller cam, the forward stop, Anti-Cam Device, must be fixed so that the Roller Lifters track in the center of the cam lobs or approximately as close to center as you can get them to center when the engine is rotated. NOTE that it only takes a revolution or 2 for the cam to walk completely forward. Now you will note that there may be as much as a 1/8" space between the back of the Cam Sprocket and the Face of the Cam Boss on the block, this space may vary pending manufacturer of Cam Sprocket. The problem here is not preventing the cam from walking forward but for what ever reason preventing the cam from suddenly bouncing back which may cause a lifter to catch an adjacent lobe, breaking the distributor gear or possible knocking out the Cam Plug on the rear on the block.

.040" is the approx recommended travel for a Roller cam. The space between the Rear of the Cam Sprocket and Cam Boss on the block will have to be shimmed. I personally do not trust Torrington Bearing Spacers as I've seen the needle like pieces totally destroy an engine when they fail. I shim this space stacking as many as 3 Solid Hardened Steel Spacers that are Moly-Lubricant Impregnated. These shims called "Wear Plates" and made by Morrosso, Comp Cams, Crane ... etc.

I also drill a 1mm hole in the Front Oil Plug on the Psgr Side lifter Gallery to lubricate the Timing Gears and any additional bearings associated with Anti-Cam Walk Devices or Gear Driven Cams.

I hope this helps.
 

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Discussion Starter #5
I have a Cloyes adjustable cover. I can set the endplay to the recommended specs. That will definitely stop forward walk. It should also stop rear movement. But, the cam gear to block face will be the stop. Thrust washers keep the cam from walking back. With endplay limited, the cam will not be able to walk back. The cam gear will be rubbing on the face of the block. Flat tappet cams have a rearward thrust because of the lifter taper. So it is fair to say factory cam gears were designed to rub on the block face.

What I don't understand is roller cams don't have the built in rearward force. If the it is okay for flat tappets to pull the cam gear against the block, why isn't it okay for roller cams, which don't pull back, to be able to be used without a thrust washer? There is less force applied rearward with a roller cam. Shouldn't I be able to get away with using a roller cam button in the front only?
 

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Discussion Starter #7
But is it enough to necesitate the washer? The flat tappet has the cam gear and the lobe taper but doesn't require the washer.
 

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But is it enough to necesitate the washer? The flat tappet has the cam gear and the lobe taper but doesn't require the washer.
Factory never used a washer or wear plate or cam button in various forms, but if you have ever see some of bad cases of wear on the face of the blocks, it may convince you to take the precaution. The timing chains limit a lot of this forward movement, especially the morse linkbelt type. You will need some type of device to limit forward movement with a roller cam.
 

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LLuciano
I have a solid roller cam, aluminum cover, and a button.
No washers. No bearings. No troubles.No extra lube but that's a good idea to drill that pee hole, they ought to do that when they put those crappy sounding noisy gear drives so they don't sound so crappy.

But I'm not worried about getting 100,000 miles.

Just 1,000 or so 1/4 miles at 7500 RPM or so would make me way happy.
Last teardown cam gear and block face were fine.
Tim
 
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