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Small 4 Cylinder Vertical Opposed Unkown

Blair Goss

Subscriber
Last Subscription Date
07/16/2019
We got this little air-cooled engine a while ago. It has 4 combustion chambers arranged in an H pattern in 2 cylinders - vertically opposed. Unlike most other opposed engines, all pistons move in the same direction at the same time on a single connecting rod and wrist pin (I suspect that it would jump around a fair bit). Bore and stroke are approximately 2x2.

A geared camshaft hangs off the mid-point of the engine which has two sets of lobes running 6 valves (3 above and 3 below). 2 intake valves and 1 exhaust valve in each valvebox. The upper heads and valvebox are missing but appears to be identical to the lower one. The mixer is also missing. The 2 ignition contacts are at 90 degrees on the camshaft.

Any thoughts? Could this be an apprenticeship project or a Popular Mechanics engine? It's well enough made that there might be a patent of some sort, but where do you start looking?

Thanks
 

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Kevin O. Pulver

Email NOT Working
Age
54
Last Subscription Date
02/14/2020
Very strange. I'm sorry I cannot help at all. I'm glad you posted pictures. The second set of pictures shows the wierd "one rod, one pin/to 2 piston, 4 combustion chamber" set up that words almost fail to describe.

SO this has 2 pistons, using both sides of each one for combustion right? Sort of "steam engine like" to be alternately pushing on both sides of the piston.

The open slot in the cylinder for the common wrist pin to move would necessitate a shorter stroke, correct?

How did you come across this thing? It sounds like a good candidate for an air compressor, but I'm assuming you've eliminated that possibility with your description of the valves and cam lobes.:shrug:
 

Bill Hazzard

Registered
Last Subscription Date
08/28/2008
A better description of the engine would be a twin double acting engine similar to a Cooper or Snow engine, just with the cylinders side by side instead of in tandem. An opposed engine would imply a crankshaft between the cylinders. If the crankshaft is counterballanced properly it shouldn't bounce around too much.
 

Blair Goss

Subscriber
Last Subscription Date
07/16/2019
Bill - thanks for the better description, I was struggling with what to call it. There doesn't appear to be any counterbalance on the crank or flywheel.

Kevin - yes, the stroke and the piston skirt has to be short to make it all work. We haven't had the pistons out of the cylinders yet to see what they actually look like. The first thing I thought was half engine - half compressor as well. But the cam and ignition would suggest otherwise. Local flea market find.

Blair
 

Ronald E. McClellan

Subscriber
Last Subscription Date
01/05/2020
My first thought was that it was an engine/compressor. But after second look it has those lever lifters on both top and bottom. That means that you would have to build a duplicate of the valve , manafold , head system like is on the bottom of the engine. That's not easy to do , I hope that you do it and I would sure like to see it when it's done. Ron
 

Blair Goss

Subscriber
Last Subscription Date
07/16/2019
That's the plan Ron. The lower head is at the patternmakers now. Hopefully we can recreate what we need from the lower half in order to complete the upper.
 

Trevor A Cole

Registered
Interesting about the two sets of contacts and only one exhaust valve at each end.
If there is only one exhaust valve at each end then both cylinders at that end need to fire at the same time. Otherwise when one cylinder was on the compression stroke the other would be on the exhaust stroke et cetera.
This follows on with ignition system being unorthodox as well. It would have to have two sets of points and two coils.... one of each for each end assuming there is only one spark plug at each end?
Following on from here the firing cycle crank degrees wise would be Bang (1 + 2 @ 0 degrees), bang (3 + 4 @ 180 degrees), exhaust (1+2 @ 360 degrees), exhaust (3 + 4 @ 540 degrees) repeatedly.
I have written this with ignition at top centre (it probably wouldn't be) and called the paired cylinders 1 + 2 and the other end 3 + 4.
This means bolt it down Blair since there is no balance system that will smooth out this engine just as nothing will keep a V6 Buick odd fire still! Thanks for sharing with us all and lets see a piston soon huh?
The Trev
 

Blair Goss

Subscriber
Last Subscription Date
07/16/2019
Thanks Trevor. One exhaust valve and spark plug at each end is correct. I'm not sold on pulling the pistons out yet. But if we need to, we'll definitely take some photos.
 

Owen Bosma

Subscriber
Age
78
Last Subscription Date
02/07/2018
Hello and Happy New Year

You do find some of the most interesting and odd engines, I have been looking closely at the pictures of this one, I do like engines that are outside the box so to speak.

Looking at the valve box it does appear that the valves are offset to one side slightly , would that effect when using it on the other end, in other words will the valve stems line up with the cam and followers.
 

Blair Goss

Subscriber
Last Subscription Date
07/16/2019
Thanks for your interest.

It appears that the two pistons in each cylinder are attached (i.e. one symetrical casting around the wrist pin). I would assume that it would have to be lubricated with oil in the gas.

Owen - based on a few simple measurements that we have taken, it looks like the valves are just offset enough that when you flip the head over to the other end, the valves are then offset over the opposite lifters. Hopefully it all lines up. :shrug:
Blair
 
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