RHOADES LIFTERS and High Pressure Oil Pump
 

Will the higher pressure of the HP oil pump affect the action of Rhoades lifters ?


At idle fully warm I have 45 psi ...2400 rpm 75 psi .


Should have stuck with the standard Oil pump to get full benefits of the Rhoades lifters ?

Oil is 5- 30 Royal Purple HPS ...with some Zddp added . 8oz of the Lucas ZDDP ..


Running temp of engine is 180 .....never gets hot.

They are not effected by oil pressure, there bleed down rate is effected by oil viscosity and oil temp and rpm and to some extent valve spring seat pressure.

When a lifter is lifting.. Trapped oil under the plunger is pushing against valve spring pressure multiplied by rocker ratio.

So plunger leak rate can be effected by spring pressure X rocker ratio.

High engine oil pressure just ensures the lifter stays full. Working pressure, inside the lifter, is way higher than engine oil pressure.

I'm with Steve on no change to leak down rate by oil pressure.

Clay

Yes it will..

Read your original post. Would your's stay pumped up or leak to fast and not pump up with RPM?

Neither would have been caused by oil pressure. So curious why you posted "yes it will".

Clay

PSI in the Lifter Bore will encourage a Pump-up, only theoretically a lot better.

In actuality, the OIL Pump PSI does matter, and the Bore clearance matters.

As for me, i stopped using Rhoads because they were a few dollars more.

Well.....I lean towards it will affect the bleed down rate , but I also see the other side .....


Wonder if anyone made a switch from high psi to low psi and saw a difference in how the lifters behaved ?

The leak is between plunger OD and lifter bore ID. During lift the valve on the bottom of the pluger is shut tight tght holding valve spring pressure multiplied by rocker ratio.

Oil weight, sping pressure and time/rpm is what effects bleed down rate. Low rpm they have time to leak down. Higher rpm they don't.

Thin oil leaks faster than thick
Strong valve springs leak faster than weak springs
When lifter is up on the lobe, engine oil pressure can't push more oil under the plunger

Clay

Reminds me; A difference has to make a difference to be a difference.

Thankx...that now clears it up for me more.


Thanks everyone ☺

I ran a Crower 69019 with Rhoades lifters and an 80 psi oil pump. LIfters performed as advertised and engine had a smooth idle. later changed the oil pump to 60 psi and no change in idle quality.

I think categorically it will affect the lifters but not to a degree that it can be noticed

Any force that is trying to keep the plunger up effects its ability to go down but again 20 extra lbs. Of oil pressure would probably equate to a micro second of difference

Iam sure such a question is aimed at figuring out if a little more pressure renders them ineffective I highly doubt that is an issue

Also worth noting is the RPM rhoads does it's best work at idle what else is going on then ?
Less than pump rated oil pressure

Once the lifter begins to lift the valve, Engine oil pressure is irrelevant. Its all in the Lifter.

I remember the lifters being just like regular lifters when the engine was cold. The valve train was quiet and the lope was back.. I tried changing oil, Full synthetic to regular, 5W30, 5W40, 15W40, straight 30 and 40. Once the engine got to operating temp none of that mattered. That out of time ticking came back. The timing kind of reminded me of the way Elain used to dance on Seinfeld lol...

I would get a Super Duty #10 solid cam, look it up it might be just what you wanted..

Number 10s usually don't live long and the streets.That lobe designe required the engines to be high idle.I tried running them a few time in the 60s with not great success in a lot of street driving.JMHO,Tom

I ran a #10 in college for a while. Lots of street driving.
Took the car on a several hundred mile (one way trip) all was fine.
Was 30 miles away from Home on the way back when one of the #10 cams lobes
failed at cruise rpm. Got it towed home and removed the camshaft and lifters after
pulling the engine and cleaning the crap out of the engine. Cam bearings were fine.
Engine bearings looked good as the lobe failed and I immediately stopped on the road.

At that point I went to the 255/260 @.050 .540/.560 solid flat tappet camshaft and drove that for several years around town.
No more long trips. Comp (Roy and Mike Mckinney grind) cam. Johnson solid lifters.

Tom V.

Could oil pressure in the lifter bore slow the 'leakage' some? I always assumed that the leakdown came out of the fill hole in the exterior shell? If the leakage occurs on top of the lifter, oil pressure should have no effect at all. In any case, any possible effect of a higher pressure pump would be a small amount, so basically little to no effect, and at 2400 rpm , rhoads will already be moving too fast to lose much lift.

lifters
 

Correct me if I'm wrong but the 041 cam and the number 10 appear to have the same timing, although the 041 has the same lift as the #10 with 1:50 rockers while the #10 needs 1:65 rockers to achieve the same lift, .447. In theory than the 041 with 1:50 rockers should be just like running a #10 but hydraulic. The 041 with 1:65 rockers reaches .516. Am I missing something hear? Mike:confused:

Well at 6 before TDC the number 10 has opened the valves .010” more then the 041 cam, though I don’t think this would make much of a performance difference other then in the vacuum seen at idle.

lifters
 

Thanks Steve. I did run a #8 in the 421 that was a nice driver but had a tendency to eat tires when you opened up both carbs. :eek: