I picked up a project 57 392 engine that came with a Neilson cam. I was told it was a roller Neilson re-grind with a blower profile and came with a box of new solid roller lifters. Card in box reads as follows: Engine 392 Chrysler Cam Grind R-570 Valve Lift .572" Duration 290° 252° @ .050" Valve Clearance .025" 112° Anyone help decipher these specs? I am not familiar with roller cams but a .572 valve lift seems huge. Thanks to all!
Have you considered calling one of the cam companies and giving them those specs and getting their thoughts? I'm not sure what information you're looking for here.
Although Chris was talented, I'm not sure how he got 572 lift on a reground roller. Those lobes gotta be small. A couple thoughts; When lifts go past 500, all else being in stock configuration, you will get the rocker tip sliding/scuffing across the valve tip (side loading the guide). Yes, lash caps will ease this but, now you are adding length to the top of the valve. Lifts above 520 really require that the shafts be moved in the stands to maintain geometry. And yes, you could buy some of the aftermarket stands that have relocated shafts, assuming they are where you need them or step up to custom roller tip rockers.
I did call Oregon cam and they did say that .572 is a lot of lift and the 290/252 duration is for a high reving engine. Not much else. Gary, I agree with everthing you said in your response above. I don't know if this is a roller or not. Either way .572 is a big lift and probably not for me as I do not want deal with all of the valve train geometry issues or build a race engine. Maybe a good cam company can figure it out if I send it to them?
The lobe is generous on the nose, almost looks like a roller. The huge duration also makes a fat nose so someone with a CamDoctor will need to look at the ramps.
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