Atlas Top Lubrication

Does anyone know if Atlas engines have any top (rocker spindle) lubrication issues? I am installing a spin on oil filter, and I have the option to feed the top from the oil tank return banjo (per factory stock), or to give it a little more pressure by taking the oil feed to the top off the oil filter inlet. A little more pressure should not hurt unless it may flood the rocker boxes and allow oil to top over the valve guides.

Opinions?

Slick

Think you will find that given the option of being forced through the oil filter, or going to the unrestricted top end, that ALL the oil may well go into the top end.
Unfiltered, too. Not what you want, at all.

Scavenge-fed oiling systems to the top end are usually downstream of the filter system, for these reasons.

Note too that Commando oil filters have a by-pass system inside the filter,
so if it becomes blocked internally, oil can still flow through it.
Not all automotive filters have this capability.
Worth checking if using other than a Commando filter.

I had a Triumph with the rocker feed plumbed into the scavenge line before a spin-on filter and it appeared to make no difference at all to top end oil supply.

It is now plumbed the sensible way, downstream of the filter.

The Atlas was not renowned for any top end lube problems, as Norton had it pretty well sorted by the 1960s when the Atlas first came on the scene.
Apart from fitting a double speed oil pump gears (six start) and a bigger holes in c/case with a bigger oil block from around 1966, this was the setup on the first batch of the Atlas powered Commandos

Bernhard said:

The Atlas was not renowned for any top end lube problems, as Norton had it pretty well sorted by the 1960s when the Atlas first came on the scene.
Apart from fitting a double speed oil pump gears (six start) and a bigger holes in c/case with a bigger oil block from around 1966, this was the setup on the first batch of the Atlas powered Commandos

Click to expand...

Commandos all had pressure lube to the top end though - unlike the first Atlas's (and nearly all previous dommies.)
If there were no problems, why did Nortons change from scavenge fed oiling to pressure fed oiling....

Better valve guide life and rocker shaft etc life is probably the answer.
But I've not actually seen that written anywhere.

Rohan said:

Commandos all had pressure lube to the top end though - unlike the first Atlas's (and nearly all previous dommies.)
If there were no problems, why did Nortons change from scavenge fed oiling to pressure fed oiling....

Better valve guide life and rocker shaft etc life is probably the answer.

Click to expand...

That's probably the answer to why they changed to pressure feed.

Might not be a categorical answer to whether it did any good, or whether there was a real problem before they did it.

Why did Triumph make the exact opposite change on their twins?

Thats funny, when you think about it !

Triumph had little reciprocating piston oilpumps.
Half the time it wasn't supplying any pressure.
Maybe taking the rocker feed out of it gave more supply to the big ends...

Rohan said:

Thats funny, when you think about it !

Triumph had little reciprocating piston oilpumps.
Half the time it wasn't supplying any pressure.
Maybe taking the rocker feed out of it gave more supply to the big ends...

Click to expand...

The Triumph pump is delivering oil for even less than half the time, because of ports in the pump bore.

The piston and spring of the pressure relief valve even out the pulses.

I can only guess, but diverting more oil to the big ends and making the rocker oil feed less sensitive to precise metering might have been reasons for changing to the "normal" dribble feed from the scavenge.

Also, a thin steel pipe carrying hot oil at 60psi up the front of the engine and thence to a tank-top pressure gauge was an unnecessary opportunity for a breakdown.