hi,

when i installed a cranecam 272 hydr.n in a 355, i noticed that, when i pushed the camshaft all the way in, the lobes wont align with the lifterholes.

so i was wondering, what prevents the camshaft from walking forward and backwards during driving?


please help,

thanx

To prevent rear movement of camshaft, the timing sprocket does this function.

To prevent forward movement, a cam buttom and a short water pump with a thick (1/16 inch thick) backing plate performs this function.

I believe World Products might sell a bronze bearing to fit between the timing sprocket and the block to fill the void. One engine I was putting together had this 1/8 inch space with the chain centered.

Maybe others here will offer their 2 cts........

The cam gear prevents it from walking rearward and the timing chain prevents it from walking frontways. If you have a gear drive, you need the cam button spacer to keep it from rubbing through the front of the timing cover.

-Mark.

its going to far rearwards.

the lobes are not centered in the lifterholes

It will be too far back without the cam gear installed on the cam. Put the gear on and you'll see that it sets how far back the cam goes.

Jody

Originally posted by rolling-robert:


the lobes are not centered in the lifterholes With a flat tappet cam, the lobes not being centered in the holes, and the convex shape of the lifter bases are what make the lifters rotate. If they didn't rotate, they would get destroyed very quickly.

That's normal.

сссссссh, that make sence, thanx!!

an engine is pretty nifty, isnt it?

Aa-haa!! The lobes, except their noses, are ground at an angle, and along with the convex lifter bottom, the lifter rotates. Now, one half of the lobes, intake, are ground at an angle in one direction, the other half, exhaust, are ground just the opposite, thus, the flat tappet cam stays centered. Look at a good used cam, you'll see the edge of the lobe shiny where the lifter ran and the nose will have full contact.

so, i installed the cam with gear and if i push it all the way in, the lobes will touch the edge of each lifter, so i think thats pretty far out -of-the-middle, isnt it?

I just dont want to build this engine and take it out after 100 miles because the camshaft/lifters are all f*cked up.


should i buy one of those space rings?

Robert,

With the cam gear installed on the cam and the cam pushed back until the gear is against the block, does the cam and crank gear line up directly above/below each other? In other words, can you put a straightedge on the face of the cam gear and crank gear in a vertical line and see that they're directly in line?

Jody