Why did Lister do it this way ?

[compig]

Was pondering the architecture of the CS and it occurred to me , why external pushrods and semi-enclosed valve gear ?  I have some opinions but would be interested to hear what you guy's think ?

[t19]

Because they look damn sexy

[snail]

compo 
   Wasn't it just the quickest way to convert the sidevalve petrol motor to diesel?
They'd already done a "proper" one in the form of the JP but I think they needed a "second line" (OK, lower cost ) version. I know this may upset some CS lovers, but isn't it "stating the bleeding obvious"?
Just trying to stir things a little...

Brian

[somian]

Equally, why did they do splash lubrication of the big end, when they had an oil pump there already. I just assumed it was the technology of the time when these things were designed. In other words, they are crude, but work well enough for 1400cc engine that is only producing 6 or 8 horsepower.

Ian

[compig]

Snail , just had a browse through my Lister CS book and found the part referring how the CS was derived from the L type. So , there we go !!  Have to agree with t19 though , visible mechanism is beguiling !!
I'm with somian on the splash thing , the bearing loads on a diesel are much higher than a petrol motor so I'm surprised it copes. Just goes to show how strong hydrodynamic oil films are.

[Oilengines]

The Lister CS 5/1 was developed from the Lister L petrol engine, and was not a new engine in its own right like the 9/1 or JP engine.

Thus, as has already been mentioned, the original engine was side valve so the CS became a conversion of that basic bottom end.

Early 5/1 engines had 1-3/4" cranks and even a wet injector. When the L engine went to 2" crank, they went the same with the CS, although it may be that the CS needed the modification first and it carried back to the L engine.

The intention was  to give L engine users a diesel option that was a direct bolt-on replacement, so the dimensions of the fixings and crankshaft height were the same on the petrol and diesel engines.

This policy continued with the Lister D petrol and the LD & SL diesels.

The oil pump and big end lubrication was a carry over from the L engine and was never changed in the lifetime of the CS. The 10/2 twins used a similar system but different pump.

There was also a much rarer petrol twin, the X engine, which was OHV, there are about 8-10 known examples, it has a lot of the 9/1 or JP about it.

Pare

[Combustor]

           The previous posts have correctly noted the history of this old design, and we should remember that these engines were made to survive in an "agricultural" environment in the hands of the unskilled, where cleanliness was rarely considered. Thus the lube system had no high pressure pump or narrow passages to block. Oil overflow
from main bearing reservoirs filled the big-end pickup tray, then gravitated to the deeper sump where the (non-detergent) oil allowed foreign matter to drop to the bottom for later cleaning as recommended,thus avoiding need for a filter, which most clients would not have cleaned and re-assembled reliably anyway. A plunger pump with a priming
lever allowed for lubrication prior to startup for those who thought to use them.  These old motors were definitely "horses for courses". Regards,  Combustor.

[oliver90owner]

Also you need to know, or remember, that many engines were oil 'splash' right into the 1950s and some of those were diesels making 12 or maybe 15 HP per cylinder with engine speeds close to, or at, 1500RPM.  The splash in their cases was usually a pump squirting oil at the big end.  Not so much difference.  I would think most were low pressure pump-fed mains though.

Regards, RAB

[xyzer]

I believe exposed pushrods are a hold over from way back and most early gasoline engines were flatheads. Overhead valve was high tech back then. Ricardo and Frontinac (sp) made overhead valve heads for the flathead Model T they were enclosed but still had to be oiled manually.  On many of the early make and break gasoline engines the intake valve was a check valve that had no pushrod. They didn't even have a crankcase for oil. They hand lubed the rod after so many hours. Later they made a cover for the crankcase and started the splash system. Higher RPM engines usually require stronger valve springs so more loads are introduced and along with heat and the need for clean lube. I know this is not a specific answer for the CS but I bet there are pieces that apply.
Dave