Do I need a Camshaft Thrust Button?

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 12:45 pm

Does anyone know whether I should be putting a thrust button on my cam gear?

As a matter of interest, if I dont, what stops the camshaft walking forward and allowing the timing chain to turn on the wee wee? Logic tells me the dizzy drive will hold it firm but surely this cant be what it is meant for as well as the obvious?

Also, where can I get three camshaft bolts, and an RB oil pump bolt set? Does anywhere sell them off the shelf (without me having to find a bolt shop and go through a possibly painful comparing exercise?)

Thanks all

Dave-R · Post by **Dave-R** » Tue Mar 29, 05 12:47 pm

Cam thrust is taken by the block.

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 12:53 pm

Good day Mr. Robson,

Was hoping you would see this thread

No button - got it.

Another question I had was on Woodruff keys.

I just bought a new one and it is a different shape to the one I had on my old 68 440.

My old one was (humour me) sort of cheese wedge (Edam) shaped from the side. The one I have been sent by 440 source.com is similar but has what I would describe as "arms" extending either end of it. Should I bin that and try and get the Edam shaped one?

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 2:22 pm

oops, i was under the impression that they had a button and we sell a ally cover on the strength of that, to stop the button flexing the tin cover slightly.
Best remove that reference from our site if it's wrong

i thought that the lobes on a standard cam were ground with a slight taper on them to try and keep the cam in place and when the cam was changed for an aftermarket one you needed the button.

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 2:25 pm

BLIMEY!!!

I have a Mopar Performance Parts 6-Pack 3-bolt camshaft and progear Billet Steel Double Roller Timing Gear and cahin for a 3-bolt camshaft.

Still no thrust button???

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 2:39 pm

I'm confused now, i've just done a search " mopar 440 camshaft thrust button" in google and there are references to them

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 2:47 pm

YOUR confused!!!

I dont suppose looking at another engine will do because if what you say is accurate Wil, I would need to know if the camshaft is original or aftermarket.

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 3:02 pm

I thought the cam thrust was taken by a bolt on plate, i wouldn't imagine the dizzy gear would hold it in place since it is not a fixed point it is a rotating shaft. Infact too much cam trhust will alter the ignition timing as it moves from forward to backward.

I am really refering to small blocks here, I don't know if it applies to big blocks.

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 3:39 pm

Well i guess that would tie in with the references to a cam button.

Fitting one would make sure the cam stayed where it was supposed to be
and keep ignition timing more accurate.

After doing a lot of reading this past hour or so it looks like the cam button is a performance piece, but there seems to be a lot of people concerned about the cam walking and the cover flexing.

So here's a question

I guess the distributor drive pushes the cam forward onto the plate? if so you have metal to metal contact between cam and plate and by design the plate couldn't hold the cam as the wear would be horrendous, it must kinda float, now to give a limit to the cam and stop any metal to metal contact must be what a button does.
It doesn't cost much and if it wears out you just pop in another one, my guess would be adjustable in some way so you could sort of limit the cam
movement.
Come to think of it i'm sure i've read something a while ago about adjusting the button clearance by denting the cover but i think that was a che##

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 3:50 pm

Here's my

The camshaft will never touch the timing cover - the gear chain will. The crank gear is pushed back hard on the crank nose. After the timing cover / oil slinger have been installed, the harmonic balancer goes on. The HB has a snout protruding from the rear that goes through the timing cover to sit on the crank gear and the whole assembly is held in place by a big bolt n washer bolted into the crank shaft nose therefore the camshaft will only move forward by the same degree of lateral play there is in the timing chain. Coupled to this, the dizzy drive gear meshes into the side of the camshaft near the front - one lobe behind the fuel pump actuator rod cam. The disszy drive cannot move forwards or backwards as it is held in place by the buch sitting directly below the drive gear. This is how it is on BB's, and it sounds different to SB's (obviously as their dizzy's are at the rear of the block and not the front).

I cant really see how the camshaft would creep forward that much, but I really am not that sure.

Jon · Post by **Jon** » Tue Mar 29, 05 4:07 pm

I think the button is a roller cam thing

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 4:14 pm

I guess the fitting of a button is only relevent if the cam has got to stay pretty much in a specific place for timing issues.

Thats probably why it's refered to in the text for our ally cover (copied from the manufactures site) "designed to stop chronic cam walk" as if you've paid the ?? for an ally cover you'd certainly want and need spot on timing and cam position or looked at from the other direction if you need spot on timing then fit a button and a stiff cover

Dave-R · Post by **Dave-R** » Tue Mar 29, 05 6:01 pm

The thrust is taken by a thrust plate on a small block. Clive was asking about a 440 and I was pushed for time so I gave him the answer he needed. No button.

Anonymous · Post by **Anonymous** » Tue Mar 29, 05 6:42 pm

So am i right in thinking if you want or need spot on timing it's time for a button

I'm only curious as i've got a ally cover listed on our site and if the info is wrong then i've got to change it thats all

Kev · Post by **Kev** » Tue Mar 29, 05 7:32 pm

Well I've looked around and seem to think they are for Roller cams. What does keep a big block cam with a gear drive and Indy front plate from moving forward and back?