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    Has anyone built and RUN one of the Upshur Twins? I built one but set it aside before I got it all done, and now I wonder if anyone else in this group has built one and is satisfied withl its running? Maybe they have some hints on its pecularities before I go ahead and finish and run my version of it? I would really appreciate some discussion.
    Thanks. Ben Imbrock
    I built the Upshur twin opposed. I could not get sustained running with carb as designed. I have gone to a carb for each cyl. located right on the cyl head. I have not tried starting the engine with the new carb setup because I had a problem with the Hall ignition.
    My shop is not heated so will resume work in the spring. Craig Hinton
    • CommentAuthorkamran
    • CommentTimeFeb 4th 2009
    Hi Ben
    I built the engine as well and I was not able to get more than 45 sec of running time. But after that I put that project aside and started working on something else and never got to it to improve it.
    I think there have been a few discussions regarding spreading the carburetor for each cylinder to improve the design.

    Now here I’m only guessing so don’t quote me on it. I think the problem is not really the carburetor desgin, but rather the intake valves. That engine is designed in a way that when one cylinder is in the power stroke, the other is in the intake stroke. So if the intake valves are not sealed completely after the engine is warms up, then it will leak and during power stroke of a cylinder it will pushes some of the combustions through the intake valve and prevent to other cylinder that is in the intake stroke to suck Sufficient fuel in. So this is why separating the carburetor may help in this case.

    Kamran...The (not closed intake valve) is a very good thought....On one of my 4-cylinder engines (each pair of the cylinders are fed by one carb) I had one side of the engine was running strong, and the other side of cylinders was running "real" weak....When I removed the head I found that one of the intake valves was being held open by a small bead of RTV , that I used as a seal for the head.....With the open intake, that side of the engine was exchanging the intake (air and fuel) charge between the two cylinders causing the engine to run weak.....I cleaned the RTV off of the head which solved the problem.....When we would go to the Cabin Fever show, Mr. Upsur would often visit our set up, and was always interested in my twin....He had a ongoing problem with his twin, and it was the same problem with the extended running....At one show we went as far as using my fuel and putting two of my plugs, to see if we could clear the problem up....The engine would run the same as before, it would start and run for a short time and then falter and quit....So the problem remained with the engine.....Mr. Upsur was a "fine" person, and he will be remembered By the continued building of his engines....Dale Detrich
    • CommentAuthorjay rich
    • CommentTimeFeb 4th 2009
    ive got a ? on the plugs and in line of flat twins how does the upsur twin distribitor work i got the plans for the enginge from model engine bulider but it does not cover the distributor well as for mine it works but i have a new problem it jumps arch in side the distributor i made all of it from black delrin and a acrlic covoe from where the coil and plugs wires come from so how can i fix this ....jay

    How big is your distributor cap, I made several and the smallest I have managed with out arcing across is about 1 inch, also in some models I have had to make the cap taller and extend the shaft accordingly to stop arcing from the top to the distributor body.
    I usually make the body of aluminum and all the interior components like rotor from Delrin, an acrylic cap not only looks good but also allows to see what is going on in arcing.
    IN the rotor case, do not extend the brass (or any other metal) strip all the way to the edge, finish it short of the edge, this helps also to prevent arcing.

    You can check some distributor designs for sample sizes and construction notes, like the v4 from Jerry Howell for some ideas.

    Best regards.

    • CommentAuthorjay rich
    • CommentTimeFeb 4th 2009
    hi jamie you got it mine is 1 inch across and made from black delrin also a acrlic cap i am going to try your trick of finishing the contact wiper a little shor see i added a cross strip to it i got the idea after look at my own from my pick up truck i gave david some up date pics of this or how do i post them here but thanks i will try this....jay
    I made my engine from the plans in MEB (and of course that meant the distributor also).. I made the distributor body out of PVC pipe fittings, but the rotor is delrin. The idea of making the cover out of scrylic is wonderful, so you can see what's going on. I don't know yet what my valves are doing, because I haven't run it. All things I will carefully check. Sure is nice to get all this help from this knowledgeable group. Thanks. Ben
    I'm watching this with interest because I'm in the early stages of building the Upshur twin. My plans were to build it with twin carbs however, so maybe some of these problems will be avoided. Either using the carb design from the Upshur singles (farm hit & miss), Webster engine or something similar to Dale's design.

    Has anyone been experiencing these problems with the Upshur singles? This may help identify if it is a carb, distributor or valve problem.

    I think the problem is not in the valves as much as it is in the design of the timing of the engine, timing of camshafts with valve opening period and overlap of valves, most engines I have built two cylinder have four lobes instead of the Upshur design with only two, and then having the pistons at exactly 180 degrees.
    I would review the camshaft and timing design before going to far, I bet you can make the engine run better with opposed cams like the ones used in the Mastiff and other similar engines.

    Now this is just a thought, have not given any detailed consideration or made any calculations of timing and valve opening.

    Best regards.
    Hello All......As a note of difference between my twin and the Upsur twin cylinder engine is the ignition system used.......All that I use is a single set of points that drive two coils.....Each coil is driving one cylinder plug....The system is running as a wasted spark ignition.....I use a 12 volt 2.3 amp hour battery, which will run through a show which starts late Thursday through Sunday.....I went the "simple" way for the ignition for this engine, and it has run OK for years....And the other thing is that I use two carbs. and a short intake pipe from the carb. to the head.....It seems as if it would be putting a load on the single set of points, still the #1 engine has been running from about 1997, and still is on the first set of points......On the two sets of cams..The VW boxer engine uses one set of cams for both sides of the engine...There is a third thing different between my twin and the Upsur twin....I have twin cams on my engine, which are timed one cam for the #1 cylinder and the second cam for the #2 cylinder.......But the Upsure engine seems to take off and run OK for a short while, then falter.....The cams are not changing from the time that the engine starts until it stops......Dale
    Reply to Garry: I have built the Upshur vertical single cylinder and used the carb designated in the plans. The engine is a reliable starter and runner and I have shown the thing here locally with good results. I also built the Webster single horizontal and used the Upshur carb on it, and that engine is likewise a good runner and the carb works very well in setting the speed, up and down the spectrum. To use standardization in the engines I build, I have pretty well settled on the Upshur carb design and it has performed to my satisfaction. Ben
    • CommentAuthorjay rich
    • CommentTimeFeb 6th 2009
    uncle dale ive look for the distributor and cant fint it in the plans for the twin and i got a good ? why does the twin fail over time ?
    Thanks for the comments, I'll proceed with the twin on the assumption I'll be using Upshur's single engine carb design. Much appreciated, as is the input by others.