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scott12180

Basic question on Knight engines

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A local acquaintance has a Stearns Knight which he'd like to sell.  Very handsome car that I was quite interested in last year, but I hesitated because of the Knight engine. I am not at all familiar with these.

 

I remember the car when it was on a small local tour as smoking terribly.  The owner considerately drove at the rear of the pack, but it was not a good impression of the car.  It appeared to be restored but to what degree the engine had been rebuilt, I do not know. I think he said he did have it apart.

 

Frankly, I could not own a car which smoked like that.  And these days, it would probably get you a traffic ticket. So could anyone give me a lesson on if this is normal, will it get better, will there always be some degree of smoke?  If I was interested in the car, how could I tell if the smoking would go away eventually, or if I would likewise be stuck with a car that no one wanted due to the smokescreen? 

 

As I said, it's a lovely car but really scares me.

 

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I understand that they smoked less as they got more miles on them, carbon would help seal them up. I suspect modern motor oil would keep them clean and continuing to smoke.

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Essentially, the exhaust smoke comes from oil between the sleeves, and the outer sleeve and the block, forced by blow-by past the junk-head rings, into the exhaust ports. Of course, you loose it through the inlet ports as well; but it is more completely burned with the combustion mixture. Oil into the exhaust ports just smokes. I fixed two Willys Knights some years ago for Tom Hogan. I straightened the taper wear with a rigid hone, and rebuilt the worn junk head rings with Metco Spraybond, which is a pure molybdenum, and finished them by grinding on a mandrel with the correct end gap to the finished internal diameter of the honed sleeves. The slight surface porosity of the coating holds a little oil. I have written all the precise details of the method in a post on CCCA Technical section of this forum.

If you read Reynolds' biography of Sir Harry Rickardo , you will appreciate how the big Daimler sleeve valve engines of the first tanks in WW1 helped the German artillery with their direction and range.

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I knew an old timer who used a 1924 Willys Knight as a tour car in the sixties. He told me every day it would burn one quart of oil in the first 60 miles, after that nothing. He could drive 200 miles and it would not burn oil. Next day same thing. It seems it takes a long time for a sleeve valve engine to warm up  but once it is completely up to operating temp, the oil burning stops.

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The basic cause of smokey exhaust with high oil consumption is loss of compression past the junk head rings.  You do need oil between the inner and outer sleeve, and between the outer sleeve and the bore it runs in.   If a lot of oil is blown through the inlet ports to burn with the fuel mixture it is not likely to cause heavy smoking.  Oil blown into the exhaust  ports will smoke badly enough to fumigate mosquitoes, ( metaphorically).  Exhaust smoke from the big slow old four cylinder Daimler sleeve valve engines in the first WW1 English tanks gave the German field artillery good direction and range to target them.  The later poppet valve engines that were built to the design of Sir Harry Rickardo did not suffer that fault.

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Hi Everyone,

 

I thought some here might be interested in some pics of my Minerva engine when I had it apart recently (and one of engine in the car).

 

Regards to all.

 

Andrew.

P1130509.JPG

P1130510.JPG

Minerva engine.jpg

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