1936 16H oil pump required

I would not normally wish to pour cold water on our resident 16H expert’s opinion that only good things have been reported on the Andover oil pump but feel it necessary to add my own findings for what they are worth.  They relate to the purchase of an AN Singles pump a few years ago.

 Amongst my Nortons I have a couple of 16Hs, a 1936 one and a 1940-ish WD.  Despite its 84 years, the early one hardly wet sumps at all, even after a few months non-use there is only an inch or so drop in oil level, I've never had to drain the sump before starting.  The WD however after a couple of weeks would spill its guts onto the garage floor if it had been left on its side stand or rear wheel stand.  If propped vertically upright on its wheels it was just about OK with regards spillage but required the sump oil returning to the tank before starting.  I refurbished the oil pump when I built the bike from a pile of bits; the pump had a nice feel to it in accordance with the John Hudson single finger spanner turning test, lots of slurpy noises and pumps well - it just wet sumped too much !  I decided therefore to bite the bullet and purchase an AN Singles pump for a little over £200.

 There was a thread on this forum 3 years ago about AN Oil Pumps (https://www.nortonownersclub.org/node/4835). Not wishing to rehash the whole saga, I take the liberty of pasting below the opening paragraphs of the above thread which seem factual and detailed:

 New A.N.Oil Pumps VERDICT

Posted by les_howard at May 05. 2017

 Fed up with excessive wet sumping and after reading recommendations on the Forum that they are so good, I decided to splash out and buy a new “Andover Norton” oil pump. I chose to buy it from RGM as they are priced the same and I needed other parts from them at the same time. Well the first one had to be sent back as it was initially impossible to turn and when I did get it turning it had a single tight spot remaining....not good methinks so sent it back. It was duly replaced with another one and this time it turned easily and to my mind possibly too easy!... On my old pump's removal, I was struck on how good this self refurbed pump actually was and doing a finger block test on the output it actually seemed to pump harder than the new one. Then I did a static drain-through test and low and behold I could see oil beginning to drain out of the feed nozzle in just a few seconds. Oh dear, I thought, I was hoping for an improvement here!

Now cut to the chase. How does it perform? Well I reckon the scavenge side does work that much better with a very high flow rate and instant priming but sadly the drain through is definitely no better. Now using fresh 40 SAE straight oil this time instead of my 20W-50 oil I was hoping for a really big improvement but sadly and annoyingly I seem to have wasted my money. I would go on to say I would have had a better improvement by leaving in the old pump and switching to the thicker oil.

 I have to say that my findings were exactly as stated above by Les Howard as far as my old pump and its new Andover Norton replacement were concerned.  The loose feel on turning the new pump did not bode well with regards drain-through.  Using John Hudson's 5" spanner test one could almost flick the rotation half a revolution with a small ring spanner attached. Incidentally, the AN nut/threads are 9/16" AF - UNF, not Whit - Cycle, as they are Commandoised.  Upon installation with timing cover off and using 40 SAE oil to check drain through, it was probably no more than a minute before a steady trickle of oil appeared through the feed nipple.  No improvement there ! 

 I would have accepted living with this had it not been for the fitting problems I then experienced in relation to the fit within a 16H crankcase and timing cover which I feel need further examination as in my opinion the AN Singles Oil Pump was not suitable as purchased for installation in single cylinder engines.

 At the 2017 NOC "In-Cider" Rally in Somerset, whilst on display in front of Wells Cathedral I was in conversation with a WD16H owner and the subject of wet sumping and oil pumps came up.  He said he had bought a AN Singles Pump when building his engine but found that the pump mounting studs in the crankcase did not quite match the hole spacing in the pump body.  He said he took both crankcase and pump to Andover to demonstrate this incompatibility and the pump body was re-machined to allow it to fit.

 Being aware of this, and assuming it might have been a one-off problem, or one surely that had now been sorted, I took my old pump with me when going to purchase the replacement. A couple of long 5/16" bolts through the old pump holes seemed to match those on the replacement well enough, so I went ahead with the purchase.

 Upon installing my new pump on the studs in my 16H crankcase it quickly became apparent that all was not well.  It slid on for an inch or so but then started to bind on the studs.  The gear and worm drive were loose enough but gentle tapping was required on the pump body to expose enough thread to allow the nuts to be put on.  As I tightened the nuts I had the sinking feeling that I had past the point of no return as the pump body was definitely getting tighter on the studs.  I fastened the nuts fully but couldn't be sure if I had a proper fit on the faceplate.  I pressed on with the oil check mentioned above and as removal of the pump now didn't seem an easy option, I tried to fit the timing cover.  I had already realised that the diameter of the AN fibre sealing washer was too big for the recess in the 16H timing cover and had turned this down by 0.025" to make it fit.

 With a coating of ThreeBond sealant to the mating surfaces I tightened the screws fixing the timing cover only to become aware of oil dripping from the base.  Peering from below it was obviously there was an obstruction inside as there was a gap of about 1/32" around the lower part of the cover.  Removal and inspection showed a gauge on the inside of the timing cover caused by the rear of the two pump retaining nuts, the gauge mark was removed and the area relieved with a Dremel sander.  I thinned that nut to reduce protrusion and allow the flat of the nut to be adjacent to the cast tunnel inside the cover which it had been fouling (Fig.1 attached). The pump installation at this stage is shown in Fig.2, the top of the reduced left hand nut is just about flush with the stud top whilst the right hand one is still a thread or more short.  I realised then that the height of the pump body had to be greater than that on the original Norton pumps.

 The tapered wooden dowel in the feed nipple is to stop oil flow whilst the cover is off – so much for drain through !

An attempt to refit the cover still proved futile as it seemed that the pump body was too tall for the space available and the top-hat / bleed nipple was fouling the outer case.  It was also noticeable that this AN fitting was of the large flange type as fitted to Twin and Commando pumps whereas all Norton Single pumps have a significantly smaller flange.

 There was no option but to try to remove the pump and measure things.  Unfortunately, the pump was now too tight on the studs to allow it to be withdrawn.  I had to grind a slot in the end of one stud to take a large square shank screwdriver fitted with a spanner.  This just succeeded in turning the stud and unscrewing it through the pump body releasing the pressure to allow easy removal of the pump off the remaining stud.

 The following measurements were made:

1.       The hole spacing in the AN pump was +0.011" greater than the original.

2.       The hole diameters in the AN pump were -0.002" less than the original.

3.       The body height of the AN pump was +0.030" more than the original, Fig. 3  clearly shows the difference.

4.       The Top-Hat / Feed Nipple is +0.042" higher than the original (Fig. 4) :

5.       The feed nipple flange diameter is a whole quarter inch greater than the original and of greater thickness (Fig. 5).  This means it interferes with the cast rim of the hollow for the sealing washer instead of sitting inside it and compressing the washer. This seems the most bizarre aspect of all as even the most cursory comparison with an original pump must realise that if for three decades Nortons fitted a significantly smaller flanged nipple to their Singles pump it was probably for a very good reason.

It would not take much ingenuity to rectify these problems. Reaming the mounting holes to allow greater tolerance, machining the outer body flats to allow the nuts to seat better, fitting a smaller feed nipple or reducing the present one, about an hour’s work, but these would obviously invalidate any warranty on a £200 item.

I returned my AN Singles pumps for refund together with the above findings and photos.  These received neither acknowledgement nor comment. I had to phone subsequently to affect the refund.

All a somewhat time-wasting and frustrating experience, especially when I believe some of the short comings might already have been known about. Nor does it do many favours for a well-respected organisation who's quality control and service to Norton owners is normally second to none.

All this was three years ago, perhaps modifications have now been made to sort the issue.  Possibly Herr Seifert’s NOC representative might confirm or otherwise, the AN Oil Pump being in fact his “part of ship”.

With regards my WD’s wet sumping, I gathered a couple of used ones and some bits at Kempton to swap around parts and refurbish and achieved a quite acceptable result at a fraction the cost of a AN new one.

Pete McDermott