oil relief valve
 

if i were to stiffen the oil relief valve under the intake manifold what would the specs be Gene

Re: oil relief valve
 

DO NOT attempt to stretch the stock spring.Add a shim bushing(you have to make it) to increase pressure supposedly.GM on here will tell you how to make it. I just done mine,but haven't started it up yet so i cant update on modification yet.ken ct.

Re: oil relief valve
 

In my opinion, there is no need for a lot of oil pressure... Oil film strength is what keeps parts from contacting. I think 30 lb is plenty. I would like to see oil flow, and that the idle oil pressure doesn't drop off. You may be asking the oil pump to work harder than it needs to... Karl

Re: oil relief valve
 

Aircraft engines either have an adjustment screw that can be turned down to increase pressure or they add washers like ken ct mentioned. Incrementally is the best way to make any pressure adjustment. Too much can be worse than not enough in some cases.

Kerby

Re: oil relief valve
 

Gene, There are no specs to get a speciic oil pressure as an end result. You need to install a temperary mechanical oil pressure gauge then adjust it to 45 or 50 lbs. These engines had an adjustable bypass valve at one time and us kids screwed them in with no idea what the results would be. This is probly why they went to a fixed spring which seems to change tention over time. I believe there is a picture in the early parts manual and may also be in some service bulletins. Just adjusting or changing the spring is like throwing a dart. By removing the spark plugs, oiling the cylinders and cranking the engine with 12 volts you will have a very good idea of what the oil pressure will be running. 1/8" brass pipe is the correct diameter for a spacer. I would crank it and check the pressure before takeing the cap off the valve. Make a 3/16" spacer out of the brass pipe and make sure the hole in the pipe clears the stem on the valve so it don't hang up. Crank it with the 3/16" spacer and see what the pressure is. If it is to high make the spacer thinner. If the pressure didn't change then you have a pretty good lose of oil some place. I think if bearings dropped the pressure that much you would have a bearing rap. I have never seen the cam bushings warn that bad but heard of it. The 3/16" size is just a starting place, don't just put a spacer in without testing the pressure with a 12 volt battery spinning the starter first. Why 12 volts? It spins it with plugs out at all most driving speed. I found if the pressure went up 40 lbs above what it was before putting the 3/16" shim in and we cut the shim down to 3/32" the pressure would only increase 20 lbs. This isn't accurite as I only did this on the first valve we ever did and was surprised to see that was how it worked. Do the test with 20/50 oil so thin oil isn't the problem. G.M.

Re: oil relief valve
 

If you're running later 8ba style pump, wouldn't that internal bypass control pressure?

Re: oil relief valve
 

I have a friend running an Ardun in a nice street rod and idle pressure is from zero to 5lbs and cruise is 30-35. Engine has8-10k miles in it, so far so good.

Re: oil relief valve
 

thanks guys, i appreciate the response, and thank you GM, was wondering how i would know what the result would be when i reassembled
it, will be a project to do before it gets down to 10 below here in Iowa. Gene

Re: oil relief valve
 

Gene
Here's what I did. Maybe it helps. After the pic was taken, I had to shorten the plunger to fit it properly. I adjusted the way GM described and have it set to relieve at 62#. :)
Jim

Re: oil relief valve
 

I think my spring may have been stretched. I have two and the are different lengths. One is about 1/2" longer. Anybody have a stock length spec?

Re: oil relief valve
 

Jim, I like your adjustable oil relief valve setup. I will plan to make some of those for my engines.

Re: oil relief valve
 

Andy no matter how long the spring is the only way to know what you will have for oil pressure is to do the test I described. Then you have what you want and your done. Putting it together without testing is like Russian roulett. Just because an engine runs at low oil pressure that doesn't mean there won't be more wear over a long period of time then one with 40 lbs pressure. I also think more oil through the engine will help in cooling. G.M.

Re: oil relief valve
 

I have shimmed the oil relief valve and raised the oil pressure about 10#s but it took 1/4 inch, what i wonder is if too much shim are the cam gears assured of oil through the indentation in the ball that seats? Gene

Re: oil relief valve
 

Slick I would try a 5/16" shim and see what happens. The spring may be so weak the pressure is still moving the spring and dumping oil causeing a pressure drop. If the pressure don't rise with the 5/16" spacer then the oil pressure is dropping do to wear or if the oil pump is the later type with a pressure relief valve that is dumping and needs a shim. The gears get all the oil they need even if the valve NEVER opens from the flat spots on the valve. G.M.