Hydraulic roller Rhodes lifters in attempt to tame cam
- Thread starter jake17201
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I don't like those lifters and wouldn't use them. Something seems wrong with the numbers you are posting. The first thing I would do is to check true TDC and compare it your timing marks. And one question did you degree it in?
You might want to try just timing it with the vacuum gauge bringing it up to maximum vacuum at idle and then backing it off a little bit just to see what happens. Run it see how it runs and then check to see where your timings at. It might not be your best answer but I would try it. Also make sure you're using quality octane fuel!
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4eighteener
Well-Known Member
Sounds like you have done this before, I have not. Would you say that each .001 of lash equates to 1° less of duration as the youtube talking heads claim?
No I don't but if you think the cam is too large I'd just swap it out for something smaller and stay away from those bleed down lifters.
TT5.9mag
Two atmospheres are better than one
I have done it, and am doing it currently. My 8.1 has solid rollers on a hydraulic cam. I wouldn’t say there is a direct correlation between lash and duration, far too many variables.
autoxcuda
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What mufflers do you have on it?
Have you tried gently closing the choke flap (or slowly blocking the carburetor by hand to see what effect it has? If it does not kill the engine, or if it is slow to kill it, my bet is on a vacuum leak. That would explain why it won't idle down. Also worth checking on, is the secondary throttle adjustment. If they are too far open, it also will not idle down. Easily adjusted by removing the carburetor.
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MOPAROFFICIAL
Well-Known Member
Thats what I was thinking...stinking on the mains.
Should be able to get a 8-900 rpm idle w a 4 corner idle and a few more degrees initial.
Accurate ltd magnum mufflers, straight thru 2 1/2
Just keep on mind that if you DO decide to ultimately use variable duration lifters, try to utilize the Z-Max. They are adjustable for the amount of duration they knock off at low RPM. With any of the rest, you have no idea how much duration you lose at low RPM, OR IF you ever gain it all back at high RPM. At least with the Z-Max, you have some control over that. I really think this is tuneable without those type lifters, though.
4eighteener
Well-Known Member
Yes, it sounds like the op is trying to make a daily driver, and not sure your application? Did you originally start off with hydraulic rollers and switch to the solids rollers and if so, did it change the characteristics for better or worse?
TT5.9mag
Two atmospheres are better than one
Mine is a turbocharged big block in my daily driver dually with 630,000+ miles on it. It ate a hydraulic lifter and killed a cam when it broke a spring somewhere around 400,000 miles, so I had comp grind a hydraulic roller cam for it. And I put hydraulic roller lifters back on it at first. Right about that time engine masters was doing an episode about this very topic and Steve Brule convinced me to try it for longevity testing reasons. The engine acts exactly the same as it did with hydraulics and it’s still running today.
4eighteener
Well-Known Member
I would say with 230k since the rebuild it has passed the longevity test!
TT5.9mag
Two atmospheres are better than one
Agree!
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