SBM Roller Lifter Choice
I don,t think I am confused about anything. We do not know yet the root cause of his noisy lifters. Are they just inherently noisy because as you say, they cannot handle the ramp, or are his lifters in the smiley face area partially uncovering the oil feed passage at full lift, or is the oil band being exposed above the lifter bore cause loss of pressure at the lifter. As the poster shows in the pics, post number 4
The lifter can expose the oil galley depending on the amount of cam lift. Some guys that have posted on the forum in the last 6 months or so have low system pressure because of the lifters.
Yet some guys have no issues at all.
I agree with you that I personally do not understand the attraction of hydraulic rollers. They cannot handle a real roller ramp to get the performance advantage, so I do not see the benefit.
A friend of mine claims that no one uses flat tap pets anymore because the steel is crap and the oil today does not have the additives to make them live, that's why he went hydraulic roller.
But his build has no issues, so not every case is the same.
I just post my experience. BTW, you should let your friend know that all flat tappet cams are cast iron. And as Kenny from Oregon Cam always says "they sweep the crap off the floor and make cams out of it".
Which is true. Always has been for cast iron cams. BTW, my first roller cam was cast iron. Those cores HATED being in a clutch car. I don't know why, but the lobes would get substrate fractures (had an engineer friend cut the cam up and look at it and I think that's what he said was happening but that was 1985 and in those days I drank a bit so I could be a bit fuzzy on the terminology) at the end of the lash ramp and cause the material to flake off. I made it better by tightening up the lash but it still happened. Ok, just a little trip down memory lane.
As for the rest of it, a quick search of most any hot rod forum and you'll see they had industry wide issues. I've had the same issues with every brand. So it's a lifter issue. Yes, the Chrysler machining adds another left handed monkey wrench to the issue, but that's on top of the hydraulics issues.
Like I said I was big on hydraulic rollers. My first 408 that made well over 500 HP was a hydraulic roller. When Cam Motion looked over the dyno sheets they begged me to either put solid rollers on it or just change to a solid roller and instead of 5200 RPM turn it 6000 and it would be close to making 600 HP.
So I've built many HR engines. When the lobes became even more aggressive then the issues cropped up.
I mean, you can get a lobe that is .680 lift and 240 at .050 (wish my Comp catalog was here) or similar stuff. You'd never get away with that on a SFT lobe. Not even close. Not even with a Comp MM lobe. But with a roller you can.
When my catalog gets here and I'm back home I'll start a thread comparing modern HR lobes to SFT lobes. Or better, maybe PRH, if he feels like it will do it.
I think that would be interesting and eye opening.