The first try of 0.160" was a convenient hex head bolt with shank that fit inside the spring to guide it & a head thickness of 0.160".

The second try was a piece of metal that I machined on my lathe. It had a short guide step which fit inside the spring & a larger diameter step of 0.360" long & diameter same as the outside of the spring. A step of more than 0.360" long caused spring coil bind before the plunger was adequately released. This on a BN2. See pic:

The six cylinder might require something other than 0.360" long. A bit of experimenting might be required. If you get the spacer too long, the spring will coil bind & the oil pressure will not be released & the pressure will go sky high. If the spring guide step is too long the same thing will happen. It just took a little trial & length adjusting.

As I mentioned, strangely, the shorter spacer did not increase the pressure enough to fully seat the valve but the longer spacer did. Don't know exactly what was going on in there.
D

Dave

Mine sort of looks like the 6 cylinder one although it is tapered all the way back from the stop end to the outside edge of the piston, i have ordered another one from my ususal supplier to see if there is a difference between them (i'm hoping initially there is and this may be my problem) if not i will check the seat and try the shimming.

Rob

Thanks, Dave. I'll see what I can come up with, my BJ8 always has low pressure (at hot idle especially). Think this is typical for the later pumps.

I had lower pressure than I liked on my 65 BJ8. I pulled it apart and found that the spring had compressed. The shop manual states it is supposed to be a specific length and mine was significantly shorter than specified. I stretched the spring to the correct length and reinstalled it, then pulled it back out and found it had collapsed back to the shorter length. I stretched it a 2nd time, this time to a longer length than specified and reinstalled it. I pulled it back out and found it had collapsed to the correct length as specified by the shop manual. It appears to me that the spring had lost it's original heat treating if it ever had any, and had developed a " memory " of sorts. It wanted to stay at the specified length but only after it was stretched further than it's original length and allowed to compress back. It also had another " memory " of sorts at the shorter than specified length probably from years of being compressed.
I ordered a replacement spring from one of our usual suppliers only to find that it also was shorter than specified by the shop manual. Unlike my original spring, the new one stayed put at the correct length after I stretched it out a little. I kept my original spring installed and my oil pressure is 60 lbs cold and 40 lbs hot at a fast idle. It was never that good either cold or hot before I stretched my original spring back to the correct length. If the pressure ever gets low again, I'll try the new spring first.

Dave

Yes my car is a BJ7 and has the stepped valve. I tried shimming the valve and this did bring the pressure up a couple of lb/"2 to about 20, so nothing great and this was with a 9mm shim, i didn't like to go anymore but it may be worth a try, perhaps upto 12mm.
Is there a way of blanking of the return valve, i.e to stop oil returning past the pressure relief valve and down the drain holes as then i could quickly assertain if it is indeed the valve not seating which then may have to be reamed out.

Several years ago I saw an ad for an adjustable oil pressure relief valve. I haven't seen an ad for one since.
Patrick

I have not tried it but possibly you could temporarily glue a piece of flexible gasket material to the nose of the plunger. In theory, this would provide a good seal.

Small leaks at the plunger face will affect oil pressure much more at low rpm than at higher rpm when the pump is putting out much more flow.
D

I have read with interest over the years this on going discussion : change springs , add distance pieces etc.. I am left somewhat confused what the 'ideal'pressure should be at different RPM's. It seems possible to me to add incorrect spring lengths and/or washers, over-pressure and blow a seal or too.

Dave

Like i say i will try a few more shims and then may get my machinist to make up some sort of blanking plug then at least i can see if this is the route of the problem.

Dave

Just reading up somewhere earlier about oil viscosity, i am using running in oil in my engine and wondered if this may have some effect to oil pressure as it does seem fairly thin.
Also i have flow to half of my rocker arms (a good trickle) but not the others some am now checking all the holes in the new bushes are aligned etc, am i right in thinking the groove in the rocker bush is at the bottom with the oil hole to the lifters drilled into the groove ?

Yes - the groove should extend from the bottom just to the oil passage to the pushrod. Not so far that it extends to the oil hole on top. Some replacement bushings have a slot that is too long & extends to the top oil hole. There should be no oil spurting from the top rocker holes. A fix for too long slots is to plug the top holes in the rockers.

Light oil will reduce the pressure but would only be noticeable when the oil is hot.

I'm not a fan of light oil for running in & would use a good 20W-50 oil which has a known good amount of ZDDP additive OR add ZDDP to the oil. Especially because of the many cranking tests done for trouble shooting.

Cam & lifter break in is extremely critical In the first few minutes of running. The engine should be fired immediately & held at around 2,000 rpm for 20 minutes so that splash oiling will provide extra oil to the cam during this critical period. I fear that the original cam breakin lube that was applied to the cam & lifters during assembly may be largely wiped off by now due to the many cranking tests. I hope it doesn't cause problems.

I just don't know what more to advise at this point. I suggest that you quickly get some "GOOD" professional help. Damage is being done by the extended cranking sessions.

I personally would disassemble the engine, verify all clearances & parts conditions, check that all internal oil passage plugs are in place & not leaking (there are many), that the oil pressure relief valve is fully functioning, that the oil pickup is not drawing air, etc.

Or you can just run the engine & see what happens.
D

I remember those; seemed they were being touted as a "solution" to avoid an engine overhaul to cure low oil pressure.

Scary, huh?

I know (firsthand) that it's possible to shim one enough to burst a spin-on oil filter (remotely mounted in an oil cooler loop) in the case of a Midget 1500 (post 1975 Spitfire engine).

What a nice mess that made; at least it was fresh/clean oil...

Dave

I spoke with the guy that did the engine and he put it down to the valve not seating properly, he also said 20lb/sp" was not a bad oil pressure and quite common for healeys !!!
I have had the rocker shaft of and just checking that over as oil was not going to all the lifters, will do that replace and put in a new oil filter in case that is clogged, then will also experiment with spacers again and see if i can get the pressure up a bit, if not that may well be a case of running for a bit and see how we go.

Sounds like a plan. 20 psi hot idle might be ok, but not when the oil is at cold idle. Not sure what you or he meant.

As I mentioned earlier, a shim of 0.160" did not improve the seating but a shim of 0.340" did the trick. The relief valve will not work if the shim is any longer than 0.360". This prolonged cranking to test for oil pressure is doing harm to the cam & lifters.

I fear that the original cam assembly lube has been mostly wiped off by now with all of the cranking. I would fill it with 20W-50 oil & add a large dose of ZDDP. On this side of the pond "GM EOS" or "ZDDPlus" is available. Find something! I would be willing to send you a bottle of ZDDPlus if necessary. I was never comfortable with the "breakin" oil that you were using.

When you first start the engine, hold it at around 2,000 rpm for at least 20 minutes CONTINUOUSLY to get proper cam & lifter breakin. 30 minutes would be better.

This means that all systems have to be ready to go, no shutdowns for leaks or other problems. Have the timing properly set before starting up. If the engine gets too hot during this period, & it well may, put a garden hose in the radiator filler, open the block drain valve, & use this as supplemental cooling.

With luck, the cam & lifters will not have been scuffed yet, you will get a good breakin, & everything will be fine.

I wish you the best my friend.

Regards,
Dave