Durango_Boy

I have a roller cam, with hyd. roller lifters. Everything is assembled, and I can see the lobes of the cam are just a bit aft of being centered with the rollers on the lifters. I have heard that the cam's final position can be driven forward a bit by tapping the cam plug at the back of the block, forward 1/8". I would have to remove the engine from the stand to do this though so it may have to wait.

The other aspect is the cam walking forward. I have a true double roller and was told that the chain itself will keep the cam from wandering forward. Is this true? With the fear that even with the chain in place and taught the cam would still creep forward, I bought a cam button. The retainer plate that came with it does not fit this cam, and while the button does fit the cam it's loose and has no way of staying unless it was pushed up against the timing cover.

That brings up another fear, and that's the wear a button will cause spinning in either the cam or on the timing cover. Does it get oil somehow? Is there some missing way for me to install the button properly?

It's an LT4 Hot Cam, two piece timing cover, and hyd. roller lifters.

Thanks

norvalwilhelm

The cam plug has nothing to do with cam postion. The cam should never touch this plug. The gear on the front of the cam touches the block and this is what keeps the cam from going out the back of the block. NOT the cam plug.
As for a chain holding the cam back that is also not acceptable. The cam has specs of only say .005-.009 or so, this is just quessing and the chain will not meet these specs.
You need a cam button and adjust it so the cam when pried back and forth fall within those specs. A normal cheap timing cover is also not good enough. You need something a little heavier. At least a good quality cover.
As for the button not fitting the cam? That I don't remember since it was 7 years ago I did mine but you definitely need the button and properly adjust the clearance.

Edzred72

Roller cam lobes do not have a pitch that spins the lifter, so it does not naturally walk forward like a flat tappet cam does. The timming chain keeps the cam from moving backwards, and rides against the block, so it's a good idea to a have a cam thrust bearing behind the timming chain. The thrust bearing pulls the cam a bit forward and should center the lobes in the lifter bore. Timken roller thrust bearings and solid brass thrust bearings are available for this purpose. Now, the cam button keeps the cam from walking forward. Most engine builders recommend .008 of play between the cam button & cam. Must allow for some movement. Your timming chain cover should be reinforced to allow for the pressure the cam puts on the button. Some aftermarket timming covers are set up for that...stock ones are not! The Cloys Hex Adjust cover is an awsome, easy to install & adjust cover specifically made for roller cams.
Eddie

Durango_Boy

I understand the cam cannot move backwards. I understand the cam cannot move forward. I will adjust the rear plug so it stays within tolerences. I have a cam button, but it's retaining plate does not fit the cam. The button does, but I don't understand how it all goes, and need a visual.

I do have a good timing cover. It's a two piece design that allows the oil pan to stay on while the tining cover is removed. It should suit my needs just fine.

What is suggested for a cam button kit? Does anyone have a part number?

bashcraft

Where did you get the cam? They should be able to get you the right button kit.

Durango_Boy

It was a custom ground kit to match the specs of a Hot Cam by an online seller from Ebay. I don't have his info anymore.

gkull

There are two styles of cam buttons and you don't really need either one unless you have a serious race machine. High quality roller chains and timing sets hold the roller cam in position. You can't hardly pry it fore and aft. tight chains don't allow it.

the two kind of buttons are part of the timing cover or some type that installs on the cam gear. Both types require .003-.006 clearance Never have the cam button ginding away while it's spinning.

You actually install the crank gear position so it holds the cam in the correct position. To far back and the cam gear eats up the thrust bearing or block. To far out and you can't clearance the timing cover.

Durango_Boy

Great to know this. The set I have is a Rollmaster set, a true double roller set. Very high quality from what I'm told. It's true it does not more for or aft easily. Since I do not race or twease high RPMs long, will I be okay with no button?

gkull

More knowledgable race engine shops don't install cam buttons unless the motor is going in a race machine capable of exceeding one "G" braking or taking off. That is the force it takes to move the cam back and forth more than the chain can hold in place. So if the cam is moving excessively your distibuter gear is also changing position.

I run a roller bearing timing cover cam button because I bought it before I knew. Not because i really need it.

Durango_Boy

Okay, thanks for the info. I'll button down the timing cover and move on. Thanks.

norvalwilhelm

Again this is NOT advisable. If the cam touches the rear plug you will just grind away at it. The rear plug only plugs the back of the motor.
IT NEVER TOUCHES THE CAM.
The cam gear keeps the cam from going out the back of the block.

George I never knew that only race motors require a button??? I thought all roller cams should have one?

norvalwilhelm

Flat tappet cams try to walk backward out the back of the block.
The timming chain has nothing to do with keeping it from running backwards. The timming chain GEAR prevents the rearward travel of the cam.

Durango_Boy

Okay, but this is a roller cam with roller lifters. Will it still try to "walk?"

norvalwilhelm

I know it is a roller cam and lifters. I was just correcting the original post by another member. Read the quote I outlined and I answered that.
All cams walk somewhat. It is up to us to retain them.

Durango_Boy

Okay, thanks so much for the help. Norval...do you agree that the chain and sprockets will keep the cam from walking under normal driving conditions?

norvalwilhelm

The sprocket keeps the cam from walking back, that is a given. As for the button to keep it from walking forward? George says you don't need it. All the things I have read about roller cams say you do and a button is manditory.
My new roller cams says I need the button.
If the cam moves forward the timing is thrown off. As for buttons I would have to look at what you have to decide if it would work or not.

Durango_Boy

Can you suggest a cam button to purchase that you know would work for this cam? The one I bought, thinking it was correct had a moutning plate that did not fit, and I didn't know how to 'mount' the cam button.

fauxrs2

Was your mounting plate too large or too small? is the cam a step nose item originally designed for a OEM roller cam block?

Little Mouse

flat tappit cams are ground with a slight angle on the lobes it keeps
the cam pushing backwards and the cam gear keeps it in
check from walking out the back the rear cam plug has nothing
to do with the cam. chevys low rpm hydraulic roller later model
blocks have a way to control front movement of the cam. I think
you should use a cam button or better yet the cloyes timing cover.

jimmygmartin

You have to use a cam button with a retrofit roller cam, the allowable tolerence for cam movement is very tight. Go to the Comp Cams web site and look at the procedure to set end play. If you don't do this your ignition timing will be all over the place and if a lifter slips off a lobe you will have a catastrophic failure. A Cloyes timing cover is the easiest way to do this, well worth the money.