IAP Performance cam questions

[wachuko]

I need to buy a set of their 42/82s(92410 Autocross Cam) - so I have been paying a lot of attention to this thread.

[ventura ace]

Perhaps it is a 'billet blank', from which various camshaft versions can be made by a final grind.

Alvon

[So Cal Mark]

even a billet blank has to be ground.

[fiatfactory]

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[FiatMac]

SteveC wrote:
"Some cams are cut from solid steel billets (like an Alquati / Pittatore / C&B) and others use cast cam blanks, definitely a material difference between the two types. Which the IAP cam is, I don't know as I've never had one to look at, but if the area between the lobes / journals has a rough (as cast) appearance, then they are likely cast cam blanks... if this area has a smooth machined finish, then they could be solid steel billet made cams...."
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Looking at my cams, the area between the lobes/journals is smooth on the IAP cams....therefore, they are not likely to be cast blanks.

Stan

[fiatfactory]

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[maytag]

I just snapped a couple of pics, and took some very unscientific measurments. Before we go furhter: don't go picking at my measuring methods. it's rough, and it's cold, and this was curiosity, not science.

Beginning with the factory-installed 2L cams; It's quite clear that they are NOT billet peices. I'm no metalurgist, so no clue if they've been nitrided, or ?? but clearly NOT billet.


The base circle on the factory 2L cam (with a reported 59k miles on it) measures roughly at 1.0275"

The base circle on the IAP cam (42/82) measures at .984"
Again, I'm no metalurgist, but these cams appear to be billet. I see no reason anyone would go to te lebgths to machine the shaft like this, unless it is in fact turned-down from a solid item. Here's some pics:

[ventura ace]

Thanks for the pictures, Maytag. Keep in mind that measuring the 'short dimension' with a pair of calipers won't represent the true base circle if the cam lobe ramps extend out past 180°, which is the case with the standard Fiat 124 camshafts. The measurements that I took with a dial indicator and protractor wheel showed that the ramps blend into the base circle at about 197° of cam rotation. This adds about .010 - .011" to the measuerment at 180° as measured with a pair of calipers. If you subtract about .010" from your measurement of 1.0275" base circle diameter, you'll end up wtih about the same that I measured: 1.018" for the base circle of the stock camshaft.

Since we don't know where the ramps blend into the base circle for your IAP 42/82 cams, I can't comment about the measurement of the 'short dimension' -- but it could be that the base circle is slightly smaller than the measurement with calipers due to the reason explained above.

If you know the lift of the cam lobes, you could calculate the theoretical base circle from your measurement of the 'long dimension': Base circle = (Long Dimension) - (Maximum Lift)

You can measure the Maximum Lift with a dial indicator while rotating the camshaft.

PS: I'm not meaning to pick at your 'crude' measurements, just offering a little clarification, that's all. Thanks again for the pictures!

Alvon

[baltobernie]

I'll be talking with Frank at IAP next weekend, and will e-mail him in advance for more info on their camshaft products.

[maytag]

Thanks for the pictures, Maytag. Keep in mind that measuring the 'short dimension' with a pair of calipers won't represent the true base circle if the cam lobe ramps extend out past 180°, which is the case with the standard Fiat 124 camshafts. The measurements that I took with a dial indicator and protractor wheel showed that the ramps blend into the base circle at about 197° of cam rotation. This adds about .010 - .011" to the measuerment at 180° as measured with a pair of calipers. If you subtract about .010" from your measurement of 1.0275" base circle diameter, you'll end up wtih about the same that I measured: 1.018" for the base circle of the stock camshaft.

Since we don't know where the ramps blend into the base circle for your IAP 42/82 cams, I can't comment about the measurement of the 'short dimension' -- but it could be that the base circle is slightly smaller than the measurement with calipers due to the reason explained above.

If you know the lift of the cam lobes, you could calculate the theoretical base circle from your measurement of the 'long dimension': Base circle = (Long Dimension) - (Maximum Lift)

You can measure the Maximum Lift with a dial indicator while rotating the camshaft.

PS: I'm not meaning to pick at your 'crude' measurements, just offering a little clarification, that's all. Thanks again for the pictures!

Alvon

An important clarification! I had assumed that the lobe measured at its' smalest point would give us the base circle..... I had not thought through the scenario you describe above.

thanks for setting me straight!

[ace124]

Ok, well looking at those pix they look very much like billets that were ground after a forging process. They are too smooth to be cast iron. Im definitely keen on a set now.

[baltobernie]

Frank at IAP checked the manufacturing spec of their cams, and assures me that their cams are ground from new billets. He also reiterates what many pros within and outside of this forum preach: Improving engine performance requires a balanced approach to compression, timing, fuel, etc.