Haven't post much lately, so heres a question.



I have a rotor pump, before I did any modification to it, at idle, I get about 10psi, 30-40 at cruise, I think thats within specs from the factory service manual, but I think its a little low, so I put a bunch of washers between the nut and the spring of the oil pressure regulator valve on the oil pump, now it idles at 25psi hot and 55-60 psi cruising.



but the thing is, with the washers in there, it limits travel of the regulator piston, I dont know if it will affact anything, but so far I haven;t have any problems.



what oil pressure you guys have in you Ys? do you guys think that 25psi at idle and 60 at cruise is overkill for these engine? is there any high pressure springs out there that will fit the rotor pump instead of putting shims and washer in it?

That used to be an easy modification. We could buy the oil pump springs at the Hot Rod shops that would bring up the oil pressure. Maybe one of the Guru's out there knows a source or maybe another spring that will work. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Shimming the spring isn’t expected to affect the hot oil pressure at idle speed providing the engine has normal clearances and no blockages.  The spring simply controls the pressure point at which the relief valve opens and thereby dictates the upper end oil pressure setpoint.  Shimming the spring will simply create more resistance for the relief valve and cause it to open at a higher pressure.  In your case, simply removing the pump, taking it apart, and replacing it would appear to have boosted your low end oil pressure regardless of what you did in the way of shimming the relief valve spring.  High on the list of possibilities is that the oil pump was pulling in some air at the inlet side and that issue was alleviated when the pump was reinstalled.

 

Too much shim can potentially limit the relief valve movement by inducing spring coil bind which then prevents the valve from fully exposing the internal hole in which it must dump oil to relieve the excess oil pressure.

 

The gear style pump in my ’55 with a 272 will bump 67-70 lbs oil pressure at a cold fast idle but will fall down to 20 lbs hot and idling.  It will still run 55 psi going down the road when hot and this is at 100K plus miles on the engine and using 10W-40 oil.

 

My roadster Y engine has its gerorotor style oil pump relief valve shimmed so that the stock spring is ~0.150” shorter which provides 90+ psi cold pressure.  Hot idle at about 1000 rpms sees the oil pressure drop to around 15 psi but immediately jumps up when the engine speed is brought up.  Going through the traps at temperature, it’s running 70+ psi pressure with 20W-50 racing oil.

Lorena, Texas (South of Waco)

Hi ted and guys, i drilled and tapped the relief spring screwin plug in oil pump and fitted bolt with locknut, washer and fibre washer. i can then externally adjust the relief pressure reading the oil guage. Aussie bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Ted,



If the roadster is only making 70# hot pressure at redline, what's the point of shimming the spring to bypass at 90#? Faster warm-up by friction-heating of the oil?

6 VOLTS/POS. GRD. NW INDIANA

The oil viscosity changes with the temperature.  Oil pressure is defined as 'resistance to flow' and cold oil simply has more resistance than hot oil due to being higher in viscosity.  When shimming the oil pump so it had 90 lbs cold, I was insuring that the highest possible oil pressure was 90 psi.  If I were to increase the viscosity of the oil being used or run the oil at a cooler temperature, then I could potentially have the oil pressure closer to 90 psi going through the traps than the aforementioned 70+ lbs.  If I had not shimmed the oil relief valve spring, then the oil pressure going through the traps was potentially going to be no more than 55 psi or whatever the stock spring tension allowed.

Lorena, Texas (South of Waco)

Pardon my ignorance guys (still learning the basics). I assume then that the pump manufacturers figure that 55-60 psi is all the pressure a stock motor needs, and higher would just create leaks/waste H.P/overheat the oil.



While shimming the spring simplest way to insure adequate pressure under race conditions, an adjustable pump would seem a more precise method, if indeed the power wasted overdriving the pump was significant, and the maximum usable pressure latitude COULD be precisely determined.

6 VOLTS/POS. GRD. NW INDIANA

Dan,

        The pump manufacturer will build the pump to Ford specs. They have no idea what bearing material, rotational speeds, style of lifters, or any other design parameters the engine designers are using. And, at 6000 rpm and 70 lbs the oil pump is using a subtantial amount of power. There's quite an aftermarket in heavier than stock oil pump drive shafts for almost every kind of engine.

Frank/Rebop

Bristol, In ( by Elkhart) 

Does anyone know the spring rate of the stock spring? I bought some at a local industrial supply that are 16lbs at 1.08". The feel a bit on the strong side. The dimensions are pretty close, otherwise - 5/16" diameter, 2 1/2" long. These are the only ones they had with dimensions which were close. There are some longer, smaller wire diameter springs that might work but I didn't get them.



Also, is there a source for gaskets for the relief valve plug? They are about 5/8" id, 7/8" od and maybe 1/32" thick. The gaskets for Edelbrock fuel fittings would probably work but I can't find a part number for them. The gaskets broke on most of the old pumps I've taken apart. I'd like to have one in hand, just in case.


Lawrenceville, GA

Oil pumps are positive displacement, meaning they produce flow in Gallons Per Minute in direct ratio to your engine speed.

You're right HoLun,  if your engine can't use (or bypass) the flow produced by the pump, pressure continues to build.  As wide-open as your bypass valve can be, if it's not enough to relieve flow, pressure will continue to build until something gives.  Usually, it's the oil filter because that is the very next thing right after the oil pump, and it's the weakest component.

You're wise to look for another spring rather than shim.

Dave

Royal Oak, Michigan (Four miles north of Detroit, and 12 miles NORTH of Windsor, Canada).  That's right, we're north of Canada.

Ford 292 Y-Block major overhaul by simplyconnected