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Old 02-21-2010, 11:47 AM
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Rhoads variable duration lifters

Anybody have experience with Rhoads variable duration lifters? They claim more power and torque in the bottom end, and vacuum over standard hyd. lifters. While reading up on them I wondered why everyone doesn't use them.
I'm guessing it's because they might not have the lope of a HP cam.
True, or false?

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Old 02-21-2010, 11:49 AM
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I ran them in a 350 with an RV cam. No idea about the lope, but I imagine it would be the same. They are louder then standard lifters.
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Old 02-21-2010, 12:51 PM
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Quote:
Originally Posted by sqzbox
Anybody have experience with Rhoads variable duration lifters? They claim more power and torque in the bottom end, and vacuum over standard hyd. lifters. While reading up on them I wondered why everyone doesn't use them.
I'm guessing it's because they might not have the lope of a HP cam.
True, or false?
They are louder (sound like a solid), I think this is one big reason they're not used as often.

They have a new V-max lifter now, that's lashed much like a solid- I have no experience w/them.

I once used the "regular" Rhodes on a 455 Pontiac, on the intake side only. I never used standard lifters in this engine before using the Rhodes, so I can't say how much (or if) they helped, but the engine had a LOT of bottom end and the vacuum was good for how much overlap the cam had.

I also built a 400 Pontiac and used them on both int. and exh. w/an HO-2 cam. The engine was strong, but as with the 455, a back-to-back test wasn't done to be able to say it increased the bottom end or vacuum at idle.

It should be mentioned that the biggest asset of these lifters IMHO, is to increase the vacuum of big cams at idle. As for more usable torque (enough to lower ET, for instance), that's better left to the individual build/cam/application.

Rhodes has a cam kit out now w/the V-max lifters:

"This unique Cam Kit together with Rhoads' new V-Max Lifter makes it possible to design a cam with extremely tight lobe centers (104 degrees). This greatly enhances low-end torque and throttle response for performance street or mild racing applications. This cam has .440" lift intake, and .460" lift exhaust. At idle the cam is reduced to .400" intake and .420" exhaust. This yields an incredible power curve with instantaneous throttle response and great upper-end power. The cam has 218 degrees intake duration at .050" lift and 227 degrees exhaust. Currently available in small block Chevy only."

Last edited by cobalt327; 02-21-2010 at 02:45 PM.
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Old 02-21-2010, 01:02 PM
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In the early 80's, my buddy chose too much cam for his street-driver 454, so we used them to tame the cam a little so we could bring the idle down so we could use the stock converter and a too-tall gear. They worked well. You have to get used to the "solid lifter clicking" though.
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Old 02-21-2010, 04:17 PM
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Rhoads Lifters

Maybe with gear drive timing I wouldn't hear them as much, you think?
The only reason I didn't change the cam in my engine was because I wanted
to keep the bottom end power/throttle response/power brake booster vacuum for my off road truck.
I completely forgot about the rhoads lifters and now I'm starting to have second thoughts about changing it. A buddy of mine put a HP cam in his 350 and claims his mileage went up a little. Don't know if I would gain that much with 4"10's though. I don't really need the power but the mileage increase would be a plus for me.

Last edited by sqzbox; 02-21-2010 at 04:27 PM.
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Old 02-22-2010, 01:28 PM
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Quote:
Originally Posted by sqzbox
Maybe with gear drive timing I wouldn't hear them as much, you think?
The only reason I didn't change the cam in my engine was because I wanted
to keep the bottom end power/throttle response/power brake booster vacuum for my off road truck.
I completely forgot about the rhoads lifters and now I'm starting to have second thoughts about changing it.
The main problem I see is- depending on how long the cam has been run- the new Rhodes lifters might not mate up to the cam during their break in.

If you decide to chance it, I'd suggest you do the whole break in procedure just as if the cam and lifters both were brand new, as I'm sure you would.

If the cam is >radical, you might consider the V-max lifters. They're designed to give even more vacuum back and, as racemaniac said above and you've probably read- are adjustable as to how much lift/duration you want to 'lose'.
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Old 02-22-2010, 10:13 PM
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I had to run them in my 350 Poncho in order to run a 041 cam ( RA4) it rattled like a sewingmachine at idle and had a hint of lope it also helped the vacum numbers ( people thought I didn' know how to maintain a car , but once the pressure built up it made the engine really wake up ) , it was a street racers secret when I was younger , you could run a lumpy cam and it would sound like you needed a valve adjustment on a stock cam or needed new lifters , but 2500 rpm and away you went ! we always ran them new on a new cam as when put on a used cam they would stick in the bores and not rotate and scoop out . the new cars use cam phasers to do what these basically do lowering the duration by retarding the lift points .
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Old 02-23-2010, 04:46 AM
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When I was in tech college and we did the build for my instructors 56 chevy, which used a 350. He had gotten the cam from one of the students and it was a lot bigger than he was told it was. Not happy with the low end power, he got a set of the rhoads lifters. He liked how they ticked like a solid lifter, as that helped with the classic performance sound of cars of that era, but he wasn`t impressed with how they operated. There were other things he could have done to help it out. he was using a open plane intake with a 750 holley carb, I told him if we used a dual plane with a 650 carb the results would likely be alot better. But he`s the type even so he could afford what he wanted he still insisted on "use what I got laying around or what I can get for free"
There was another student who did a build with a massive cam and he too later installed some rhoads lifters, he said he honestly couldn`t tell any difference. I hadn`t seen any advertisements for them in years, I don`t remember any in the 90`s either. But I have plenty of magazines from the 80`s and there`s lots of ads on them. I`ve never used them and likely never will, I`ve always been conservative on my cam picks.
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Old 02-23-2010, 06:06 AM
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IMHO, they are a band-aid for a poor cam choice. There are so many choices for cams out there these days, and methods and software to help picking the right cam, there really is not much reason to use them.
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Old 02-23-2010, 07:42 AM
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Quote:
Originally Posted by Rickracer
IMHO, they are a band-aid for a poor cam choice. There are so many choices for cams out there these days, and methods and software to help picking the right cam, there really is not much reason to use them.
I remember now about ad's when Rhoads first came out with them. The whole point of useing them was to be able to run a bigger cam while having good driveabilty on the street. The best of both worlds especially when used with automatic's and low stall speed converter's.
Example; My 71 Javelin probably would have been a good canidate for them because of the Borg warner cast iron tranny and stock converter. In 71, there wasn't a lot of choices for my tranny, and with the 3:54:1 rear gears and the 280/460 crower cam, it was tough trying to idle in gear and the bottom end power sucked. I won most of my races at Tuscon by catching my opponent while still in first gear. and crossed the line in second. I also made 1,000 mi trips from the base in Arizona to my home in SD cal. at 16mpg hwy.
I wouldn't say that it was a poor cam choice but a poor tranny/converter/rear gear choice. In that case, I believe the band aid would have been for that drive-line choice not the cam.
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