Cox Diesel engine with no teflon disk or o rings!

colibriguitars Sun Sep 15, 2019 9:19 pm

hi guys!
here my first Cox engine dieselized with no teflon or o rings.
made a cast iron slave and contra piston... here the pics!
waiting for a test run, but it has burst with a prime with engine in my hand....

Cox Diesel engine with no teflon disk or o rings! Img_4310

Cox Diesel engine with no teflon disk or o rings! Img_4312

Cox Diesel engine with no teflon disk or o rings! Img_4311

colibriguitars Sun Sep 15, 2019 9:21 pm

more pics....

Cox Diesel engine with no teflon disk or o rings! Img_4314

Cox Diesel engine with no teflon disk or o rings! Img_4313

Cox Diesel engine with no teflon disk or o rings! Img_4315

Oldenginerod Sun Sep 15, 2019 9:37 pm

Nice job. Looks really well made. Have you used a heavier duty crankshaft? I'd be worried about over-stressing the crank pin and ball-joint.
Not sure what Valentine engines use, but I'd never seen discs or o-rings used in diesel engines prior to getting involved in the Cox scene. I grew up with diesels as a kid and they all only ever used a contra-piston close fit in a sleeve.

Hope you have good success with it.

Rod.

Mike1484 Mon Sep 16, 2019 9:43 pm

O rings have been in use for 65 years ( O.K. and McCoy ) on contra pistons . I really like that slave cylinder set up . New to me and I've made a few diesel heads in my time . And yes a Diesel crank or heavy duty crank is a good idea if you plan a long life for your engine .
Mike 1484

Oldenginerod Mon Sep 16, 2019 10:02 pm

Mike1484 wrote:O rings have been in use for 65 years ( O.K. and McCoy ) on contra pistons . I really like that slave cylinder set up . New to me and I've made a few diesel heads in my time . And yes a Diesel crank or heavy duty crank is a good idea if you plan a long life for your engine .
Mike 1484

It only seems to be U.S. engines that use an o-ring. Not sure why that is or what the perceived advantage might be. The only thing I can think is that it may cut production cost by not having the extremely fine tolerances of the contra-piston fit used in European diesels. The o-ring also gives the engine another potential point of failure.

Surfer_kris Tue Sep 17, 2019 5:22 am

Yes, we never understood the teflon and o-ring stuff on this side of the pond... Shh

One can also make a proper counter piston inside the head, without having to modify any cylinders. This was sold as an after market product here in the early 80-ties, the smaller counter piston diameter gave an easier tuning:

Cox Diesel engine with no teflon disk or o rings! Zoom10

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Cox Diesel engine with no teflon disk or o rings!

Cox Diesel engine with no teflon disk or o rings!

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Re: Cox Diesel engine with no teflon disk or o rings!

Re: Cox Diesel engine with no teflon disk or o rings!

Re: Cox Diesel engine with no teflon disk or o rings!

Re: Cox Diesel engine with no teflon disk or o rings!