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  #1  
Old 03-28-2002, 07:27 AM
turbotim23 turbotim23 is offline
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Default anyone out there used Rhoads lifters?

Hi I woulld like to hear from anyone who has tried Rhoads lifters. I have been told that my cam won't be streetable.I/d be willing to put up with the lifter noise if they work.Most places I called said bad things about them. I wonder how many have really tried them. Thanks Tim
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Old 03-28-2002, 08:33 AM
fox fox is offline
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I've used them, years ago. They are a good product but I am now more aware of cam action and it is simply a bandaid. If you are building your motor trust a cam company and put the right one in it now. If you have the wrong cam/too big and cannot aford a swap they will tame the cam down.
If you need some, e-mail me. I have a set for mopars and a set for bow ties! jrfuchs@warpnet.net.

fox
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  #3  
Old 03-28-2002, 05:43 PM
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rumblefish360 rumblefish360 is offline
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I used a set with a purple 288 dur. cam. They work and noise wasnt that bad. Like said.."Band aid."
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Old 04-01-2002, 04:44 AM
Karl43 Karl43 is offline
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They work great. I have used them for years now. I put them in every engine that I build. Don't use the other brands - trust Rhoades.

I have used them with performance cams and also stock cams. Even with a small cam they bring up the idle vacuum and low end torque. I had a 318 with 10.5:1 compression and a 252/410 cam idling at 24" Hg at idle. When I put on 360 heads to lower compression the vacuum dropped to 22.5". Car ran great with lots of low end torque. I got 18.8 mpg with an A-body and a 2.76 gear on a 318 with a 4-bbl carb and performed well also. I am trying to get 20 MPG from a small block on the highway.
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Old 04-12-2002, 12:33 PM
HankL HankL is offline
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Here's a recent US Patent that talks about the pros and cons of variable duration hydraulic lifters:
========================

United States Patent 5,623,898
Bruton April 29, 1997

Inventors: Bruton; Murl L.
(7735-52 Mission Gorge Rd., Santee, CA 92071)
Appl. No.: 586971
Filed: January 16, 1996

BACKGROUND OF THE INVENTION

The invention relates to hydraulic valve lifters and more specifically to variable duration valve lifters.

Variable duration hydraulic valve lifters are an improvement upon the basic hydraulic valve lifter which has applications in high-performance engines. The radical cam of high-performance engines causes valve overlap which is effective in improving engine performance at high speeds, but causes very rough engine performance at idling. The variable duration, or "bleed down", lifter solves this problem. U.S. Pat. Nos. 3,921,609, 4,524,731, and 4,913,106 are directed to prior art variable duration hydraulic valve lifters. Thorough descriptions of the purpose and functioning of bleed down hydraulic lifters are found in these patents.

When an engine is cammed for more power, its ability to breath is effectively increased by opening the valves wider and holding them open longer. Keeping them open longer is known as increasing the duration of the cam. Theoretically, the exhaust valve of each cylinder opens when the piston reaches bottom dead center of the power stroke and remains open as the piston rises to top dead center on the exhaust stroke. At this point the intake valve opens and the exhaust valve closes. This is generally speaking how the valves are timed on a stock engine.

In order to extend the total duration of the valves, the exhaust valve must open before the piston reaches bottom dead center and close after the piston reaches top dead center, and the intake valve opens before the piston reaches top dead center and closes after reaching bottom dead center. This gets into a situation known as overlap: the intake valve opens before the exhaust valve is fully closed producing a period when both valves are open simultaneously.

At high rpm, despite the overlap, the increase in the ability of the engine to breath increases engine power. However, at low rpm, just the opposite is true, and the more radically varied the cam is, the greater is the overlap period, and the greater the power loss at low rpm. A car modified with a radical cam is hard to start, idles very roughly, and lacks low speed power.

At low and mid-range rpm (3500 rpm or less) the overlapping of the exhaust and intake valves being open at the same time result in a loss of horsepower and torque, result in incomplete combustion causing increased emissions and a decrease in gas mileage.

Stock factory engines are set up to primarily use engine oils such as 5 wt, 10 wt, 20 wt, and 30 wt. They are designed to use multi-weight oils such as 10-30 wt, 10-40 wt, 15-40 wt, etc. Existing variable duration valve lifters having straight external grooves in the external surface of their plungers, such as described and illustrated in the Rhoads patents, cannot function efficiently with multigrade engine oils. The oil passes along these grooves in spurts and not with a controlled steady flow. The recovery time for the oil to leave the reservoir areas of the variable duration valve lifters, pass along their respective external grooves and return to their respective reservoir areas is excessive making their operation inefficient.

It is an object of the invention to provide a novel variable duration hydraulic valve lifter that will reduce emissions by accomplishing complete combustion of the gases burned in the engine.

It is also an object of the invention to provide a novel variable duration hydraulic valve lifter that will increase an engines horsepower and torque.

It is another object of the invention to provide a novel variable duration hydraulic valve lifter that will increase gas mileage.

It is a further object of the invention to provide a novel variable duration hydraulic valve lifter that can be used effectively with multiweight engine oils and which can provide a controlled steady bleed flow along its respective external grooves in its plunger.

It is an additional object of the invention to provide a novel variable duration hydraulic valve lifter that can drastically reduce the recovery time for oil to leave the reservoir areas and pass along their respective external grooves of the plunger and return to their respective reservoir areas.

SUMMARY OF THE INVENTION

The variable duration hydraulic valve lifter described herein is designed to provide favorable characteristics over the entire speed range. At low and intermediate speeds a closely controlled oil leak in the pressure chamber is permitted to prevent pumping up to a wholly solid condition. This is accomplished with uniquely configured grooves in the outer surface of the plunger of the valve lifter. These grooves extend the entire length of the upper portion from its top edge to its bottom edge and also on the bottom portion from its top edge to its bottom edge. Each of these grooves has a greater width at their bottom end than their width at their top end. The width of the grooves at their top end is in the range of 0.0042-0.0612 inches. The width of the grooves at their bottom end is in the range of 0.0150-0.0625 inches. The configuration of these grooves is referred to as a pyramid type cut. Also the depth of the grooves may increase from their top edge to their bottom edge. The depth at the top edge of the grooves is in the range of 0.0075-0.0150 inches. The depth of the grooves at their bottom edge is in the range of 0.0080-0.0180 inches.

Control tests have been conducted on a 1991 Ford pickup truck that was tuned-up to factory specifications. Then it was sent to a California smog station for testing. Once the smog testing was completed, it went to a wheel dyno for horsepower and torque testing. Thus provided with an accurate starting point established, the Ford pickup had the novel variable duration hydraulic valve lifters installed. No modification to the vehicle's engine of any kind was required nor was any retuning of the vehicle necessary following installation of the novel valve lifters. The Ford pickup was tested again at the smog station and on the wheel dyno. The testing revealed that the novel valve lifters made the following improvements: 91% reduction in hydrocarbons at idle, 37.5% reduction in hydrocarbons at 2500 rpm, elimination of deadly carbon dioxide at idle or at 2500 rpm, increased air flow through the engine, and 7.9% increase in horsepower and torque from the engine. The engine's warm-up time was also cut in half. An additional benefit was that there was an increase in gas mileage from 18.6 mpg. to 20.7 mpg.

The use of variable width grooves and/or variable depth grooves in the external surface of the plunger of the variable duration hydraulic valve lifters allows them to be effectively used with multiweight engine oils. In prior art variable duration valve lifters such as the Rhodes lifters, the external grooves in the plungers had a constant width and depth. It was therefore difficult for the oil in their respective reservoirs to enter the bottom ends of their respective grooves and also insure that there would be a continuous flow of motor oil up the length of the grooves. As a result, spurts of oil would be ejected from the top ends of the grooves instead of a controlled continuous flow and the valve lifters would operate inefficiently at low and mid-range rpm. This produces a lose of horsepower and torque, incomplete combustion causing increased emissions and a decrease in gas mileage.

The use of variable width grooves and/or variable depth grooves in the external surface of the plunger of the variable duration hydraulic valve lifter also decreases the recovery cycle time considerably for the oil to leave the respective reservoir areas at the bottom of the respective upper portion and lower portion of the plunger, pass along their respective external grooves and return to their respective reservoir areas. The recovery time can be reduced by as much as 50 percent or more.
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Old 04-12-2002, 08:00 PM
Doug Wilson Doug Wilson is offline
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...well....duh!
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Old 04-12-2002, 08:49 PM
turbotim23 turbotim23 is offline
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Default anyone out there used Rhoads lifters?

Thanks for all the repies Guys.I liked the the last post about Rhoads not working well with multi-vicosity oils! I have Rhoads lifters already,Tring to decide if it's worth tring them.Engine builders I talked to said they don't consistantly control lift and duration and are very noisy.I can live with noisy.Could it be these people didn't use the right oil with these lifters?What if I used 30 or 40 weight racing oil? Would this give the best chance of working? Thick oil would have to help control the spurting you talked about. Since I have these I would use these before buying something else.My reason for using them is I'm going to use overdrive.this drops the cruising rpm down to where cam doesn't work well on highway. Thanks again for the repies!
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Old 04-13-2002, 01:41 AM
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SpeedSleaze SpeedSleaze is offline
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I've used rhoads without problems and no noise. Definite improvement. Look at a lot of high tech machinery being built these days- variable valve timing, variable intake manifolds...
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Old 04-13-2002, 03:14 PM
HankL HankL is offline
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I think one of the things to be learned from Bruton's criticism of the Rhoads design is that there is a 'Optimum' oil viscosity to use to make the Rhoads style lifter work best.

So I would go ahead and try the Rhoads with a good 30 wt oil, then trying blending in some 40 wt or 20 wt oil as an experiment.

My guess would be that the 40 weight oil would cause the Rhoads lifters to behave more like conventional lifters, but the 20 wt would cause them to be more 'Rhoads like'. This based on the idea that the flats ground on the lifter pistons inside a Rhoads allow more leakage with lower viscosity oil, and less leakage with high viscosity oils.

Ever wonder why Mobil One 5W-30 oil gives slightly better fuel economy?

Most times this improvement is said to be because of lower friction...but

It might be that the low viscosity Mobil One oils cause the conventional hydraulic lifters in engines to become slightly 'Rhoads-Like' at 1500-2000 rpm highway cruise conditions. This is like a lower duration cam, which would be better for low rpm, part-load cruise condition in an engine.
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Old 04-13-2002, 06:20 PM
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SpeedSleaze SpeedSleaze is offline
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My oil pump had the overkill HEMI pressure relief valve, and killer pressure to go with it. I often wondered if that was why the lifters were quiet.
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  #11  
Old 04-19-2002, 10:35 PM
Karl43 Karl43 is offline
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I have Rhoades lifters with the high pressure spring and they work great. They even tick a little.
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Old 04-20-2002, 05:04 PM
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SpeedSleaze SpeedSleaze is offline
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Mine helped a lot. The cam was unknown, set up for a four speed. But the lifters never sounded like solids.
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Old 04-21-2002, 12:37 PM
turbotim23 turbotim23 is offline
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Default anyone out there used Rhoads lifters?

Ok let me ask this question.How radical of cam have you used Rhoads with and how streetable was the result?I plan to use the Mopar 509/292 cam in a 383 big block.This is a 3000-7000 rpm cam. Thanks
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