This is a joke right?

Shannon86, do a search for "SStrokerAce" on here and you'll see that A LOT of people here come to Bret for camshaft advice.

 

I just cant believe he is all pissed off beause someone knows just as much if not more and is doubting his word. He really dosent know what he pretends to. I dont care how many post he has.

 

Oh boy.

 

WHY DO YOU SAY THAT????? ????

 

As in a torsion bar suspension with stiffness affected by the dia. of the shaft, a cam's torsional rigidity is affected by the minimum dia. of the shaft. If that minimum dia. is altered due to a change in base circle dia., the shaft's rigidity is compromised. The force that would twist the cam(shaft) is obviously generated by the action of spring tension transmitted through the lifters.

Edit: Have no documentation as to the amount (degrees) of twist possible per 'X' amount of spring tension applied but it is a force to be recognized. A little off topic, but it can be astounding the amount of torsional crank twist that can be experienced in a fueler without it snapping. A person would not imagine this possible, but as cam twist, it is.

Understandable allegiance notwithstanding, that statement in and by itself doesn't mean squat! Now you are hinging Ace's credibility on the decision/choice of others whose credibility has not been determined.

 

Again the material between the lobes is considered the barrell.Do you understand that part? ok. The barrell is always smaller than the base circle. So no matter if it is a large base circle or a small base circle the barrell is the area that absorbs the torsional twist. So again I say there is no *******way that base circle affects stiffness of the camshaft. If the cam was so large that the lobes would need to be undercut into the barrell or if the cam has been reground and undercut then it would affect stiffness.

 

The torsional spring rate of a shaft is proportional to the 4th power of the shaft's diameter so a small change in diameter makes a big change in stiffness. Because the area between the lobes is smaller than the base circle diameter, when it is reduced even a little to allow small base circle diameter lobes, the torsional stiffness drops dramatically. A 1.00 inch diameter bar is about 52% stiffer than a .90 inch bar.

So IF the area between the lobes is reduced to clear the lifters when using small base circle lobes, the torsional stiffness IS reduced.

That's what you meant, right?

FWIW, coil springs are really torsion bars that have been coiled. The stresses in the wire are torsional.

 

Isn't that what I just said? [QUOTE ]If that minimum dia. is altered due to a change in base circle dia., the shaft's rigidity is compromised.[/END QUOTE]

[QUOTE ]The barrell... base circle.
If the cam... it would affect stiffness.[END QUOTE]
You've just contradicted yourself. Maybe it is you that doesn't understand.

 

The barrell is never reduced on a small base circle unless it is undercut. I understand the torsional power of a bar of steel but when the bar stays the same trosional stiffness dosent change. Now who sounds like they dont know anything.

 

If you wouldnt change s&it around it wouldnt sound like that.

 

When we orederd my cam for the 396, we had to use a small base circle to clear the rod bolts, and had it ground on a billet core.




Nick

 

I know OldSStroker has seen a few cams in the shop where the base circle and the barrel where one in the same, so yes it does happen and it is commonplace.

Bret

 

But it still dosent affect stiffness if the base circle is no smaller than the barrell.

 

While I am not an expert on cams, I do understand that their is a science behind it and that technology continually improves designs and efficiency. Putting your question aside, the XFI grinds should yeild superior results when juxtaposed to the older XE grinds.

 

But it does...a cam where the base circle is at barrel diameter will be less rigid than one that has a larger base circle simply because of the radius from barrel to lobe.