I'm doing a COMP Cams retrofit roller swap and I'm running the Edelbrock two-piece aluminum timing chain cover: http://store.summitracing.com/partdetail.asp?part=EDL%2D4242&autoview=sku

Edelbrock tells me to use a nylon cam buttom, which COMP happens to make:http://store.summitracing.com/partdetail.asp?part=CCA%2D202&autoview=sku

With my timing chain set, I had to grind down a good bit of this cam button to get it to fit under the cover. I was wondering how much clearance or endplay of the camshaft/cam button should I have? Thanks

I set mine at 5 thousands, I believe that's generally the rule on cam end play, maybe somebody could confirm this.

Interesting. .005'' seems very tight. Does this allow room for expansion of the cam?

Ryan, I believe .005 is as tight as you would want to go and .007-.008 would be about the max. you would want to go. My understanding is you want wiggle room but not to much.
You may also want to consider contacting the manufacturer for their recommendation.

Thanks John. A member from another forum found this from COMP:

Checking Camshaft Endplay
Camshaft endplay refers to how much a roller cam is allowed to move back and forth in the engine.
.005” to .010” endplay is required to eliminate the possibility of wear occurring as a result of
interference between the cam and other engine components. Excessive endplay is detrimental as the
cam will be misaligned to the lifter bores, causing the roller wheels on the lifters to run off the edge of
the lobes instead of on the center. Another important effect of camshaft endplay is that as the cam
moves back and forth, it advances and retards the ignition timing at the distributor gear.
The proper amount of endplay is between .005” and .010.” This can be checked using a dial indicator
and magnetic base on the front of the engine. To do this, push the cam as far back in the engine as
possible, zero the indicator on the upper timing gear, and then pull the cam as far forward as it will go.
The indicator reading is the amount of endplay in the camshaft.
In Chevrolet engines, the front cover must be in place to check endplay because it is the front stop for a
roller cam. A cam button is used to take up the additional space between the timing gear and the front
cover. These are typically made of Teflon™/fiber or steel. The steel buttons have a miniature roller
bearing built in. All types are available from COMP Cams® in various lengths, depending on what
front cover you are using.
The Chevrolet front cover design makes using the dial indicator technique of determining endplay
difficult. Some of the front covers have an access hole with a pipe plug in it to allow a dial indicator
extension to go through the hole and contact the upper timing gear. The stamped covers have no such
provision. An alternate technique that can be used is to gently insert a long screwdriver in one of the
lifter bores and carefully pry the cam back and forth using the sides of the lobe in the bore. Do not use
excessive force to try and move the cam. Estimate how much endplay exists from the movement of
the lobe, and adjust accordingly. If the endplay is too much, install some suitable shim material behind
the cam button and recheck. If it is too small, carefully remove some material from the back of the
cam button, reinstall it in the timing gear, and recheck.
One final note of warning, stamped steel Chevrolet front covers are typically very flexible where the
cam button contacts them. This is detrimental to maintaining a consistent amount of endplay.
Washers are available to weld inside the cover to stiffen it. Also, the water pump fits tightly to some
front covers and can act as a support. For most race type roller cam applications the use of a cast or
billet aluminum front cover is strongly suggested to eliminate any front cover flex-induced change in
endplay. COMP Cams® offers two and three piece billet aluminum timing covers for big and small
block Chevrolet engines.

Also interesting about the cast or billet aluminum timing cover and the flex that a stamped cover can have. I for one am using that STAMPED aluminum Edelbrock cover and am wondering before I install this cam again, should I look into a beefier cover? I'm thinking so...

When do I know if I need a steel roller, aluminum, or nylon cam button? My Edelbrock stamped steel timing cover calls for strictly ONLY a nylon cam button, but I was looking at cast aluminum covers and they don't specify. Wouldn't the nylon or aluminum cam button be best for an aluminum timing cover?

Ryan,
You definitely do NOT want to use an aluminum button on an aluminum cover. Like materials do not like to rub against eachother. I use the nylon ones on evrything I do and have never had a problem with them. They are a lot easier to trim to the correct length. I use a small belt sander. I personally do not get too carried away with the amount of end play. I think anywhere between .010 to .025 is fine and will not cause any problems. Most of the time I just get them to "zero" without a gasket and then whatever the thickness of the gasket is is my end play and seems to work just fine.

I have a cast aluminum cover and a roller button.... all's good so far.

Oh, thanks Bill...still gotta give you a call about that oil issue with my dad's car.

I used the steel roller type with a stock steel stamped cover and a adjustable stopper that I Macgyvered up to retain a stock look. If memory serves me the one I used is in the link

below. Maybe some body else will comment or call the manufacturer and get their opinion.

http://store.summitracing.com/partdetail.asp?part=CRN%2D99165%2D1&autoview=sku (http://store.summitracing.com/partdetail.asp?part=CRN%2D99165%2D1&autoview=sku)

scooped: slow type...

I used the steel roller type ...

John,

The roller ones work fine but ..... I have found more than one of the little snap rings and rollers in oil pans before when tearing engines down. I prefer to keep things simple, therefor the nylon / teflon buttons.

Good to know Bill, I will keep that in mind on the next build.:yes:

Now I'm worried. :eek:

Thanks Bill...now I feel relieved