NEED HELP WITH DIESELS Report This Post | | Revisions: 1 (Post No. 1)


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I converted a Cox .049 to a diesel head I am using the David diesel fuel for 1/2A. I put a small prime in the exhaust port it will fire on the second time I wind it up (it has a spring start) but it runs for about 1 half second until the prime is gone and then dies. I have tried dozens of times but I have never got it to run. I sure wish I could figure out how to keep it running. I have tried turning the needle valve in and out. I have starved it of fuel and gave it so much it flooded but I can't get it to stay running.
No one around here runs diesels that I know, and no one sells the diesel fuel. I know if I can get it to run I will like it. Most everyone that writes about diesels love them. They say you get more power from Diesels.
I have turned the compression to where it just fires and maybe 1/2 to 3/4 turn more in very small degrees. I don't know if The problem is compression or fuel.

Any help will be appreciated

I am assuming that the engine runs perfectly on glo fuel, and has excellent compression. If not, you have a lost cause.

Now, given the above, the trick is to open the needle about 1/2 to a full turn more than glow running, then, just keep screwing down the compression until it will keep running. At that point, be prepared to back the compression off as it warms up. Once you have it running, you can slowly lean out the needle 1/8 turn at a time and fiddle with the compression to find the optimum setting for each needle position.

At some point, it will die suddenly. You have found the point where you are too lean. Open the needle about 1/4 turn and leave it there. From here on, pretty much just play with compression. Once you have a really good setting, you MAY be able to start the engine on the running setting, and not touch any adjustments. This is the ideal.

From there, you probably only need to change compression settings to match the weather of the day. The needle setting is probably good enough for all weather, and need only be touched if you change brand (or age) of fuel.

Thanks Larry, I got the engine running today. I love the way it runs. Its a reed valve engine so I didn't try to max it out. It turns 11,500 rpm's with an Master Airscrew 7-3 prop. I may be able to get more out of it, but with the reed valve engine I'm not going to try. I don't want to break the crankshaft. I really like how it runs very consistent
Sincere THANKS

Not bad you are swinging a 7 inch prop it will pick up more as it runs in , Davis does make a
heavy duty crank for that engine, the 6 inch will turn better than 14000 but think you are better
off with the 7 inch Those numbers are very close to my norvel 061 (same head) turned 12000
with 7 inch master airscrew