Installing Custom Roller Cam per FABO reccomendations

Wyrmrider said
YR
what most cam tech guys miss is that chevy is a short rod motor and much more tolerant of intake close as it takes many more crank degrees to move the piston around BDC
long rod engines are much more fussy
Around TDC it's the other way around
Chevy jerks the piston away from TDC much quicker than a long rod motor so they start opening the valve earlier to get it open when piston demand needs the flow
the same degrees of overlap is not as big a deal on a short rod motor as a long rod motor
etc
using the same specs on a SBC or BBC as a SBM or BBM leaves performance (however you describe it) on the table
what's the difference in torque that .030 lift and the implied increase in duration at .200 and area under the curve indicates?
WE went through this drill with a major fleet and also with the San Jose Municipal Busses where we dropped the EGT by 800 degrees (propane) with cam optimizations while giving more power and fuel economy

nm Engle is similar- good quality, good wear, easy over the nose (no little pointy chevy lobes) both have more area under the curve
but both series of lobes are dated but we are not talking "heads up" requirements are we

I agree. My problem is actually getting lobes that are designed for a .904 lifter. And I'm not sure for most of what most guys are doing, that they'd see a benefit with a .904 lobe.

I'd have to run through the Comp lobe listing and have a look because I don't remember many .904 lobes being under 235ish at .050 and its damn hard to convince some of these cam guys it's worth doing a .904 lobe.

I still have all the cam specs from when I built my engine a few years back. Only one cam grinder gave me a .904 lobe. That was Jim at Racer Brown. And I had better than an hour on the phone going over the junk I run before he actually decided I wasn't nuts and that netting .600 lift was actually worth doing. If I would have accepted less lift, I would have most likely ended up with an .842 lobe...maybe .875 if I was lucky.

Sometimes it's a matter of who you know, or who you can convince you aren't off your rocker. Jim was the only guy I talked to who was willing to go with that much lift for my engine.

Maybe tomorrow I'll go over the Comp lobes and see how many .904 lobes are under [email protected].