Do I need a Camshaft Thrust Button?

Anonymous · Post by **Anonymous** » Wed Mar 30, 05 8:35 am

Cheers Dave - no button

Anonymous · Post by **Anonymous** » Wed Mar 30, 05 10:29 am

I've read quite a bit on this just now and again only what i've read

"on a standard or hydraulic cam the lobes are ground with a slight taper to gently keep the cam towards the back"

Roller cams by design can't have a taper ground onto the lobes so the cam can do what it likes within the restrictions of the chain and the distributor gear so the timing could be anyhow.

So i guess if there's a roller in there you button it

Although Mopar Action fitted one to their big block that has a hydraulic cam just do a search on "440 thrust button"

Ivor · Post by **Ivor** » Wed Mar 30, 05 1:03 pm

I'm not sure I agree with what you've read Wil about the lobes being taper ground to stop cam walk.

I have always understood that the cam lobes were taper ground so as to keep the lifters turning and avoid generating wear in one spot on the lifters...but what do I know I'm only a humble engineer!

Dave-R · Post by **Dave-R** » Wed Mar 30, 05 1:14 pm

I would have to check if there is any taper but the lifters sit off-center on the lobes to rotate them rather than any taper doing that.

Ivor · Post by **Ivor** » Wed Mar 30, 05 1:24 pm

Cheers Dave...in the words of Mister Wiseman...I'll get me coat.

Dave-R · Post by **Dave-R** » Wed Mar 30, 05 1:26 pm

Narr. What do I know? I'm a bloody Audio Visual Technician.

Anonymous · Post by **Anonymous** » Wed Mar 30, 05 1:57 pm

And i know nothing as i was quoting what i read

Dave999 · Post by **Dave999** » Thu Mar 31, 05 6:46 pm

not very helpful but i thought i'd chip in that aussie 265s have terrible cam endfloat problems because the only thrust comes from the oil pump and the dissy drive (well thats a lie they are supposed to have thrust from one of the cam bearing faces but it doesn't work)

Chrysler Australias answer was to drill the timeing cover weld a nut to the outside, then turn down the end of a bolt harden it and screw it in leaving about 1/2 mm play between the end of the bolt and the dead centre of the cam gear.

i.e cam floats but not far enough to snap your oil pump mountings.

bodge
but works
Official chrysler bulletin was issued with details on how to do it !

otherwise you can buy whats know as a torrington bearing timeing set.
rollmaster (australian) make em they do them for the 265 don't know if this add-on extends to their small and big block stuff

cam gear has a thin bearing (caged i think) that bears on the block and the back of the gear.

the steal timeing cover is preferd because the small ammount of flex it has avoids the bolt bodge wearing out and cuts down on shock loading when the end of the cam hits the bolt

Dave