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Re: Pressure fed oil pressure

Hi, i strongly suggest some approriate trial and error testing with different oils. I run no 4 twice in 25 years, once due to a blockage (long story!) and once when id filled the engine with what i had lying around, some cheapo 15-40. A sustained period of 6000 and it was rattling. I normally use Valvoline VR1 Racing 20-50 in high spec vintage engines likely to get some stick and my experience is that the low revs pressure holds up well on this oil, 20+ at tick over 50-60 at revs. Oil is cheaper than engines. All with an oversize A7 pump. Saw 6800 on Drumhouse at the weekend! Good luck, Winston

Location: knee deep in chains

Re: Pressure fed oil pressure

Winston Teague
Hi, i strongly suggest some approriate trial and error testing with different oils. I run no 4 twice in 25 years, once due to a blockage (long story!) and once when id filled the engine with what i had lying around, some cheapo 15-40. A sustained period of 6000 and it was rattling. I normally use Valvoline VR1 Racing 20-50 in high spec vintage engines likely to get some stick and my experience is that the low revs pressure holds up well on this oil, 20+ at tick over 50-60 at revs. Oil is cheaper than engines. All with an oversize A7 pump. Saw 6800 on Drumhouse at the weekend! Good luck, Winston


I've run no 4 big end as well.
No 4 on a pressure fed engine is a long way down the crank from the oil entry and has a hard life. When you strip a pressure fed engine no 4 is usually noticeably more worn than the rest. As a precaution now I always spin the engine on the starter until I see 20 lbs on the gauge. Only then do I switch on the magneto and start the engine. Last time I stripped the engine after 6 years active use the visible wear on no 4 big end was no different from no 1.

Charles

Re: Pressure fed oil pressure

Winston

As you said oil is cheaper than an engine.

I had the sump off for piece of mind this weekend and checked no4 big end, i was pleased to find it looks like new.

Its running 1 1/2 crank with shells and has a high flow cylindrical rotary pump, not a bored out Austin vane type. Hopefully this is overkill for me

There was some sludgy deposits in the bottom of the sump and have checked the pump for any signs of scoring of which there are none. I will check the pressure relief but just need to lift the block to do so.

I will flush the whole oil system out and run it on some race oil. But wear the previous fill had been washed with petrol some 10-40 was an improvement>

Thank you both Charles and Winston for you input you have been a great help and I should sleep this week.

Many Thanks

David



Re: Pressure fed oil pressure

Hmmmm worried about my engine... Having to press Ulster into service at Silverstone this month as Nash not ready. I see 60 psi cold at tickover - which is 1500rpm, and 0 psi when hot. 60psi hot at 6000rpm+

I saw 7000rpm in top at Snetterton last year.... but thats another story!

Location: in workshop

Re: Pressure fed oil pressure

Mark,

What do you have for seals in the oil feed bush? Where in the system is the oil pressure gauge? Do you have a filter? I would measure the oil pressure at the oil bottle / nose cone by a separate connection ie not a t piece in the oil pipe.

Regards

Rob

Location: The 3D shed, Tewkesbury

Re: Pressure fed oil pressure

I run an engine with a Allan Reaburn pump (ex Hilman Hunter i believe). When I first started I had an overly strong spring in the bypass valve and read 120psi on the gauge before it ruptured. After experimenting I am now running at ~50psi at most speeds up to 4500 RPM. My crank is 1 1/2 inch with shell big ends and I use an industrial 30 weight oil.

Location: North Vancouver Canada