Oil pressure slow to rise

600 miles completed with running in oil all good. Oil changed to Millers Classic 20/50 and WIX WL7078 filter fitted, on start up pressure seems very slow to register. have just completed 100mile run pressure sat at just over 40 psi while driving and 20 psi at tickover but still slow to rise on starting.
Any ideas? Should I be worried?

How slow is 'slow?' On my BJ8, I usually see some oil pressure on the gauge within 3 seconds of a cold start. I think that varies somewhat with the amount of cranking you had to do to get the engine to start.

Also, if you haven't had your oil pressure gauge calibrated or checked against a known good gauge it could be the issue. My BJ8 showed almost zero oil pressure at hot idle for the first 100K miles of my ownership; obviously, I had pressure or the engine would have seized long ago. When I got the safety gauge serviced and calibrated, I 'gained' almost 20PSI at idle. If your spin-on filter is mounted horizontally--there are two types of adapters--some oil will drain back into the engine despite having an 'anti-drainback' valve (the original canister type--mounted vertically--are actually superior in this regard)*. I figure the filters are half-empty after sitting for a while, as some oil will drain back through the outlet port.

* I always 'marveled' at some of the old Ferarri engines that had two oil filters mounted on the front/top of the engine; with their in/outlets down; presumably, the engine would be started with the oil filters completely empty (not a good thing IMO).

Bob, thanks for reply, just started from cold. 7 seconds to reach 20 psi, 15 to reach 60 psi. No cranking, fired on first push.

That does seem a bit long. No idea what could cause it, besides the need to fill the filter, and/or a 'lazy' gauge. I looked up the spin-on filter you use; it looks to be larger diameter but 'shorter' than the Wix 50516 I use on my cars (BN2 and BJ8). What kind of spin-on adapter do you use? Mine is just a thick disk that bolts between the block and the filter: https://www.bpnorthwest.com/austin-...ts/oil-filter-adapter-spin-on-bn4-to-bj8.html.

A known good gauge somehow connected to the pressure 'pickup' might rule out the gauge.

Did the engine get a new pump? Might be worth dropping the sump and making sure the pick up pipe isn't drawing air. Also you could look at some bearings and make sure the engine was properly clean out and that no dirt has damaged them.

i bought a rebuilt BJ8 engine from California and it self destructed in a few miles thanks to bead blasting grit in the oilway. I had to completely rebuild it again at vast expense.

The inlet port of the oil gauge has a restrictor in it to stop the pulsations of the pump bouncing the needle . It probably has a spec of dirt in it restricting it even more .

Convinced the oil filter was the problem, I replaced it with one of the same make and model which I had on the shelf, no change. Now I'm thinking maybe this filter does not have anti drain back or is not designed for horizontal installation, my adapter is an alloy disc bolted to the block. I fitted a K&N HP-2009, no change, I'm now convinced its not the oil filter.
The gauge was rebuilt recently by AH Spares.
Next one on the easy list is the restrictor suggested above.

Passed a fine wire through the restrictor, pumped oil back down gauge feed line, no change.

What was the weight of the break-in oil? And there were seemingly no long delays to build pressure with that oil?

I once rebuilt an engine for my 100/6 (like 30 years ago...) and painted the entire inside of the block with Glyptal (electric motor insulating varnish__look it up) and my oil pressure became a cause for concern too. Upon removal of the sump__really easy in a Healey__I found the most of the Glyptal had flaked off and was all stuck to the pump's pickup screen.

For the cost of a gasket/oil and a half-hour of your time, you could rule that out. It's possible too, that I was tipped off by either finding flakes in the oil drained, or by cutting apart the filter, but too much water under the bridge to remember those details. I have never painted the inside of an engine block since though!

If nothing has changed but the oil and filter, we must assume that there's something going on in the oiling circuits and its components.

When did you put the spin-on adapter on? Mine are different--the Moss ones that are smaller in dia. but use longer filters--but they can be mounted two ways. The one I got for my BJ8 had 'TOP' marked on it, but the one I just put on the BN2 did not. I agonized over which way to mount it, and blew air through the channels in the OEM adapter to determine which was inlet and which was outlet, and mounted the adapter accordingly, and as far as I can tell got it correct (the pressure indications are more-or-less the same as with the original). On any Healey filter--spin-on or original element type--the oil is forced from the outside of the filter element into the center, from which it returns to the engine (AFAIK all oil filters work this way, but there may be exceptions). If your adapter was mounted incorrectly you might get the symptoms you described, and probably worse symptoms--seized engine from oil starvation, possibly--over time.

From what I remember of the spin on filter there are only two holes in it and they both line up with the holes in the block.

GLYPTAL is ringing alarm bells, I built this engine around 20 years ago but didn't use it until this year, as I knew it would be in storage for a while (not intended to be 20 years) Glyptal seemed a god idea at the time.


Sump off next.

Odd ... there should be 4 holes; one each for inlet and outlet, and two for the bolts. The ones I have are like this:

https://www.bpnorthwest.com/austin-...ts/oil-filter-adapter-spin-on-bn4-to-bj8.html

... and they could definitely be bolted-up incorrectly as the hole pattern is symmetrical vertically and horizontally.

Pulling the pan may prove helpful, especially if that glyptal has let go and migrated down. A simpler thing to try first might be to reinstall an original oil filter canister and filter and give that a try.

Removed sump, a little sludge in the bottom, a few blobs of gasket goo and a snapped valve stem oil seal. The Glyptal is all still intact, the strainer is clean. I ordered a new oil pump, gasket set and thrust washer. The pump was out of stock but the remaining parts arrived, old pump removed I decided to check for wear, it is a rotor type and looked perfect to me. Reassembled pump packed with vaseline, the new thrust washer was about 20 thou thicker than the one removed so decide to fit new one, reinstalled pump with new gaskets.
On a cold start the gauge now rises steadily after a couple of seconds.
Maybe the rotor was lifting due to worn thrust washer or maybe the pump to block gasket was not sealing, but all looks good now.
New pump order cancelled.

Congratulations on solving the problem. Obviously, it wasn't just a faulty gauge or your imagination.