Guys, Anyone had any trouble running 600 thou lift with the stock 454 Mag Gen 6 roller lifters. They have done 250 hours but look in pretty good shape, run smooth and the engine hasnt been worked to hard. Cheers. Jas

I just put the crane "741" Cam in my gen 6. I believe the the lift is around .641 or close to it. My stock lifters worked fine. I checked and they didn't raise out of the bore or drop down below the dogbone. Different manf may have a different base circle and that could cause problems.

lift over .580 (ish) causes the oil groove to drop below the pressure passage in the bore. There are potential long term valvetrain issues because of this.

Also, with a moderate performance cam, lifters and springs are ready for the trashcan at 250 hours anyhow. A 741 and springs are running on borrowed time at 250 hrs.

741 Lift is 610/632 Crane says to change the lifters, but I've seen many motors with the stock ones that have had no issues.

Mike, when you say that it drops below the pressure passage, what issues to you see it cause?

low hour problem, or 200+ hour problem?

I changed springs and retainers to go with that cam. If the lifters fell below the oil supply it wouldn't oil the rockers would it?

Get a set of Morel Marine Hyd rollers from RMbuilder. Morel added some features to its existing hyd roller lifter to improve the performance for the marine user. They have no lift limits, will operate in sustained higher rpm and not pump up, and they are worth some power as proven in independent testing. Best of all they are fully rebuildable so after a few seasons you aren't out another $500. A full rebuild on these runs about $185 or so.

Chris Straub
Perf. Mfg. Rep

Yeah. You get the picture.
Each block is a little different, so obviously some bores will oil and some won't. Running right there at the edge of the limit will eventually show you which ones don't.

All you gotta do is watch it at idle. If you're oiling fine, then don't sweat it (watch each rocker). The only other issue is how close you are to dropping out of the retainer plate with the valve on its seat (keeps the lifter pointed in the right direction).


mc

I had to replace the existing Comp Cams top of their line hydraulic roller lifters this past summer---one colapsed on me at start up, but thankfully didn't do any damage. I decided to have RMbuilder/Bob Madara send me some Morels lifters and I replaced them all in both engines. As far as I could tell, the oil pressure was up by about 3-5 lbs and the engines acted a little stronger throughout the entire RPM range. I also like the idea that the Morels are fully rebuildable at less than half the cost of new.

The lifters sit nice in the retainer plate. I have spun the engine on the starter with no plugs and all roller rockers oil nice. I have installed a high volume pump which in hindsight may have been a mistake. The 454 run at 50 PSI and now does 50 on the starter. I wil look at replacing the lifters at the end of the summer i think after this advice. I only have one poker run to do and then its just short bursts and heaps of fishing and drinking while you guys up in the northern freeze your Tits off. Thanks for the advice, Jas
P.S we can still go out 10 munits and catch a chili bin full of good eating snapper up to 10 pounds most days.!!!