I would be interested to learn what methods people have used to reseat the oil pressure relief valve. So far I've tried tapping another identical ball against the seat with a long drift (no improvement at all) and attempting to burnish the seat with a "hole sizer" (in effect a 7/16th ball on a stick), whch produced a small improvement but is very tedious. I might add that I am attempting to do this in situ on a ten stud Ulster engine, so the valve is relatively accessible. It would be nice to avoid engine out and disassembly but I am resigned to that if I must.

All magic fixes gratefully received!

Regards, Stuart

Stuart

I gave up and blocked it off. Mine was however the standard "inaccessible" valve.
There's now a remote pressure relief valve on the bulkhead that bleeds the excess back into the extended oil filler tube (magneto based engine).

Probably not the answer that you wanted!

ps - when's your book out?

c

May I tentatively ask why this is an issue? I have built 16 engines and admit that I have never "done" anything to the relief valve seating. I always replace the ballbearing and spring. I fit an overbored oil pump and modify the cam shaft rear bearing. The oil pressure can ,when cold,consistantly be up to 40 psi , but only briefly, and then settles down to about 4psi when thoroughly warm, using a good classic 20/50.

bugger, mine gets down to about 2 when hot, nothing at idle. I always thought that normal. Is it

Thank you Charles, a very good answer and one I shall seriously contemplate if I have to take the engine out. For reasons not relevant to this thread I may have to do this anyway. I have become uneasy about the lubrication of the blower drive bearings - long story - and it strikes me one could lead the blown off oil from a remote valve to the timing case.

Mac, I've never had problems with a spit and hope engine. In the engine in question the oil pressure starts to fluctuate at about 40 psi. At the desired pressure (circa 60-65 psi) the needle was flickering almost too fast to see, until I laboriously "improved" the seat, albeit insufficiently. Now it flickers quite fast with an amplitude of about 3 psi.
I think the problem is more likely to occur in the 10 stud engine because the relief valve is above the sump and is not continously bathed in oil when the car stands; more chance for the seat to corrode, I'd say.

Ah yes, the book, thank you for asking, Charles. I was promised the final proofs "after Easter" so perhaps I should make a call. I begin to fear that by the time it appears everyone will have lost interest!

Regards, Stuart

PS What oil are you using, Hedd? I used to get that with "Silver Knight" at ten bob a gallon.....S.

Currently a 20/50, though it was just the same on the Morris's 30 i used before an oil change.

Hedd

I think the guys are refering to pressure fed engines?

My "spit and hope" runs well of the scale when cold but settles at about 8 psi when really hot and flying on a run, BUT my gauge reads zero at idle, and from what I gather this is normal?

Steve

I once talked to some one who replaced the steel ball bearing with a teflon one. I have no idea weather it worked but it might.
Am I correct in thinking your vibrating needle at a high pressure means you are getting pressure variations while the valve is open. If this is true then it is a vibration of the ball on the end of the spring.
Put a second smaller spring inside the first one to change the dynamics maybe?
Pat

Hello Stuart.
I've had a go at the odd pressure fed engine and got good results from grinding the valve seat, ie use the ball on the stick but use fine grinding paste as you would with a inlet valve. You may need to renew the ball every so often as you are also grinding that to. The reason for the pressure flutter is because the ball is cavatating and bouncing off the seat, Paul Bonewell makes a torpedo type valve that opperates some what smoother and stops this.

Hi Stuart,
I've nevered ground the seating, I've always found that it's aluminium. Much better to put a new ball in position and give a sharp tap via a brass drift to seat it. I wouldn't be happy aout using carborundum on an aluminum casting.

Some further developments from the garage of the flickering needle.
Continued with tedious burnishing process, achieving gradually less fluctuation in the needle, until it became apparent that improvement had ceased, leaving a small but perceptible flicker. At this point began to wonder if the ball was still bouncing, so used a short length of brass tube to lock the ball onto the seat; flicker unchanged. By this time I'm fairly confident I've achieved a decent seat, so suspect (maybe) oil pump base/rotor clearance greater than desireable and permitting interesting recirculatory effects - or something more arcane!

Oil pressure at 2000 rpm circa 62psi with ball locked up, so to my mind acceptable. Thanks to all for suggestions to date. Engine out soon anyway to sort worn blower drive bearings so will take opportunity to investigate oil pump then.

Regards, Stuart

The most annoying thing I ever had was what I think was a microscopic bit of swarf/debris managing to get itself under the ball such that it didn't seat and gave virtually no oil pressure. Equally, not enough oil pressure to lift the ball off its seat to clear the debris. Gave rise to a rather long, messy and tedious job for about a 2 minute correction of the problem...

Hugh thats nothing,

My dad and is pal got a beatle stuck in the oil pump inlet on their 750 racer in the sixties, the car was so loud whoever was driving didnt notice the noise when the number 4 big end melted and kept going until the big end bolts let go. The conrod was left behind and was cut off by the crank the next time it came round!!!

All good fun but beware of beatles!!!
Regards

Rob

Which one of the Beatles was it? John, Paul, George or Ringo??
Andy