Lifter Foot Load

[Taylor]

Thousands?

 

[BuickGN]

Originally Posted By: Taylor
Thousands?


Just a guess but on the nose of the cam you may only have 1/2 square inch of lifter touching cam. Proabably less in most setups. That in itself would mean doubling the psi.

 

[Taylor]

Yea, probably less than that. This is an example of a cam with higher lift and stiffer springs that stock. So obviously I was expecting higher pressures, and although it makes sense I wasn't expecting them to be that high! I wonder how a stock set-up would compare!

 

[Taylor]

Then you need to figure the amount of time that pressure is exerted on the nose? Intuition says the most wear occurs at lower speeds (idle), so your cam is spinning ~400 rpm's.

So the worst case scenario is at the exhaust lobe's nose's at idle speeds, no?

 

[Taylor]

I guess what I'm looking for is the cam face loading

 

[Taylor]

So the number I'm looking for is going to be thousands of psi per sq in and will vary depending upon engine speed. Arriving at a exact final number would prove to be difficult to say the least. With enough time and research I could probably figure it out, but I don't have the time right now. At the nose it will decrease as speed increases, howerver at the flanks it will increase as speeds incease. I guess this is why engine speed is so important on run-in.

The reason for askng was I read somewhere there is a direct correlation of this pressure and the need to EP/AW add's to prevent scuffing. I'm sure there are also many other variables, I.E. film thickness etc. I was hoping to determne if an OTC SM oil would be sufficient for my semi-built stroker. That and I find it very interesting.

Anyways, thanks for all the help.