340 Cam Comparison
Have you ever taken a cranking pressure test with a stock camshaft and measured it again after installing a late closing, large duration camshaft.
Yes and no
I have had three cams in my 367; the 292/292/108; the 270/276/110; and the current 276/286/110
With each one I back-calculated the Scr to achieve about the same cylinder pressure, with the new Ica. So my Scr for the first cam was 11.3, with the second it was 10.7 and with the last it is 10.95. The pressure variation between them was only about 3 to 5 psi, and that was probably due to my changing the installed centerline, after the calcs were done, on account of I'm not anal enough to move a cam 2 degrees, from where it drops in, lol, especially when I already have 180psi or more . I mean if I only had 150psi, and could get 3 more psi for 2 degrees well ya, I'm going for the 3psi.
With the 292* cam I moved it three times, not to get more pressure cuz it had lots, but to move the power around a bit. and finally, to get a lil more power extraction out of it, in a misguided bid for fuel-economy. Forget it with the 292!
I can tell you that I did not like the street combination of the 292* cam and 3.55s with a 2.66 lowgear. The power-peak did not arrive until ~5500/46 mph in first gear, and it liked to be shifted way higher than you might imagine; top of first was 6000/50mph, but I usually carried that out a lot deeper. 7200 was 60mph......
I know the 3.55s were all wrong for that cam, but 3.55s was all that I wanted to run.
I pulled that cam a couple of months later, in favor of the 270/276/110; then I was a happy happy guy. The 270 made tons more low-rpm torque, a fatter midrange, still revved to 7200 albeit with less power. But since both cams spun the tires to past the speed limit, I didn't miss the lost power. That wouldn't come until the third cam went in.
I can also tell you that I will never go back to a low-pressure engine. Even my 2.5liter OrlandoDD is pushing over 200psi; what a sweetheart. Ok well the 6-speed helps,lol.
