Crank Case Oil Filter G12

CR · Post by CR » Sat Dec 16, 2006 5:15 pm

Rossco, if you have a relief valve at the timing side end of the filter tunnel you do not use the 'tampon' filter! You must use the correct filter for that year which had a fine metal gauze fitted over a heavier metal gauze frame, all of which was silver soldered onto the cap which seals the chamber. The gauze length is such that it stops about 0.5 inches away from the pressure relief valve, thus giving it plenty of room to operate correctly. On some models (certainly around 1962) the whole assembly had a felt cover stitched around the gauze. The problem with this was that it was impossible to backflush during cleaning and quickly became contaminated to the point where it collapsed through hydraulic pressure - thus cutting off the oil supply to the engine (usual result was a rod through the cases).

Do you have a one-piece cap and filter? If not you really need to find one or you'll have to leave the filter out completely rather than trying to fit a tampon filter.

Eric · Post by **Eric** » Sat Dec 16, 2006 11:46 pm

OK Alan I will concede that I really meant the filter cap. But as CR describes above my filter unit is really an all joined up unit with the gauze being silver soldered to the cap, so I just said it was within the filter.

Biscuit · Post by **Biscuit** » Sun Dec 17, 2006 9:58 am

And I'll concede that I wasn't considering the gauze filter, apologies Eric.

paul knapp · Post by **paul knapp** » Sun Dec 17, 2006 11:11 am

Rossco, what CR describes ties in with the parts drawing/description in the archives, ..shows filter and screwed cap as one item!...one part number!
Paul

Rossco 265 · Post by **Rossco 265** » Sun Dec 17, 2006 12:32 pm

CR To the rescue...Muchly appreciated for that highly detailed reply And thankyou thankyou thankyou! It did Sink in!..and I appreciate all other replies as well
obviously by what CR Describes (I have the wrong> Filter!!! for the 61 apachedamn
I will rectify this immediately
wondering if/..Im pushing the boundaries by fitting an oil cooler as well as the Norton return filter that Ive already got? To the front downtubes.
would the old girl have enuff (Heart )pressure to Run both? in the lines?
Again Many thanks in advance

CR · Post by CR » Sun Dec 17, 2006 9:37 pm

An oil cooler presents very little resistance. Bear in mind that the return pump is of exactly the same construction as the delivery pump (but twice the flow capacity), and we've already established that the delivery can create 150 psi with ease. The pump's normal pressure will easily push the oil through a cooler and a modern filter (use a spin-on type filter with a built-in over-pressure by-pass for safety).

My question would be why do you want to fit an oil cooler? I remember from my trips down-under that it get's a tad hot down there in places and that could be a good reason. Towing a sidecar would also put a strain on the engine and that could require extra cooling. But overall, most riders cruise at around 55 to 60 mph and for a well assembled twin, that's really not taxing this engine. It's actually not even running 'on cam' at that speed (unless you're running sidecar gearing).

The oil should get hot. If you're using a multigrade (e.g. 20/50) it'll not even begin to thicken up until it does get hot - over 55C. The reason that there's a heat shield on the oil tank is to protect you from that heat - the oil tank is a good cooler and radiates heat away quite rapidly. The AMC twin pumps are probably the best performers in the business and with the high-capacity unit shifting 55 gals per hour it's already providing a good degree of cooling by getting the oil around fast (and therefore taking the heat out fast). If you run the engine too cold it'll not perform at it's optimum level. This year in the UK we had July temperatures of 35+C and neither of my twins had any difficulty with running hard at these temperatures (using 20/50).

CR · Post by CR » Sun Dec 17, 2006 9:58 pm

I've uploaded an photo of the one piece oil filter that we're discussing in this thread. Hopefully it will be in the gallery under Parts-Post War Twins within the next few days.

ajscomboman · Post by **ajscomboman** » Tue Dec 19, 2006 7:01 pm

I'd have to agree with CR regarding the fitting of an oil cooler, if you're not lugging a sidecar around it's not worth the effort.

I have a cooler fitted to my 650 as during the summer the oil gets really hot, with the lower gearing the motor has to work that bit harder. I run on 50 monograde (lets not start on about oil again please chaps) and for the last 9-10yrs have had no problems.

If you still want to go down the oil cooler route, the cooler i used was a 6 row Serck Marston type used to cool British Leyland Mini gearboxes. It fits snugly between the underside of the petrol tank and the engine steady.

ajscomboman · Post by **ajscomboman** » Tue Dec 19, 2006 7:03 pm

Forgot to mention that the 650 is an outfit hence the fitting of the cooler

Biscuit · Post by **Biscuit** » Tue Dec 19, 2006 9:36 pm

Now I thought the lower gearing was there so the engine doesn't work that hard. Won't mention oil but just took the timing cover off the twin to fit a new magneto gear, and oh, how clean it is!!!!!