QuestionQUESTION: Hi Howard,Ray again.
Sorry about the mix up with the last answers .When I said I had a look under the pistons I took out, I should have said the original pistons I took out were both black underneath.The rings on those pistons had the numbers and the word 'top'written on the top.The half of a dot was on the rebore rings ,one dot was up and one dot was down and that is why it was using oil,as you said.The Harris rings were black and the half of a dot is only small and my eye sight is not as good as it use to be . When the rings were in for the short time they have a shine and the dot is more visible now.Maybe the timing caused the first problem as the cams make it a bit harder to time and to get the mixture correct,as you can't get it very even at an idle,very LUMPY. Regards Ray.
ANSWER: I had an old man come into a dealership I was working in and I was tuning an MG. I had the MG connected up to an exhaust analyzer and a scope and he took interest so I showed him a few details. He told me he was a mechanic on Model A and Model T fords in their day and he had to adjust idle mixture without any test equipment. Here is the method.
Warm the engine up first and set the throttle stop screw so it is idling as slow as possible. Then turn the mixture screw which ever way made the engine either smooth out or speed up a little. Then set the idle back down so it is barely running and adjust the mixture screw again which ever way it speeds up. Quickly you will arrive at a point where if you adjust the mixture screw in either direction the engine will quit. Then set the idle stop screw up to normal idle. Done.
I tried it on several cars in the shop and then checked it on the exhaust analyzer and they were always correct. I even tried it later on several different kinds of electronic injected cars and it worked.
The ignition timing must be correct first though.
The reason it works is because an engine develops the most horse power when the mixture is slightly richer than the ideal mixture (stoichiometric)and by idling very slow the engine was laboring to just keep running and when the mixture was too lean it lost power and when it was too rich it lost power and when he got it to idle very slow it was just slightly richer than ideal.
Does this bike have the older carbs with the throttle cable operated throttle slides or does it have the vacuum operated slides? Doesn't matter on idle mixture as both have a idle mixture screw. This adjustment procedure does not have anything to do with any mixture above idle.
Howard
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QUESTION: Hi Howard.Me again Ray.
I understand about the mixture, but the problem I am having, is setting the timing correctly as the cams are that lumpy you can't get the motor to idle slow enough to set anyhting spot on,as you think you have one thing right but it may not be as the other is out? and as I said I think that has been the problem all the long.I am at the stage I'am going to put the standard cams back in ,it's a shame as it goes like a scalded cat on the road.I am waiting for parts and will keep you up to date on the progress when it is going again.Regards Ray.PS I allso have some PANTHERS 1935\1936\1938 600CC.NOT FINISHED YET.
AnswerAll of the older Triumphs I worked on had a static timing quoted and you didn't need to have it running to set timing. It is a complex process to set timing to something other than what the factory recommends. Each time you modify an engine you change what the ideal ignition timing is. You can not guess at it. The ideal timing (most horse power) is just before detonation. Most engines require that the timing be below that figure because of the fact that many other things effect detonation. Grades of fuel, air temperature, engine temperature, load applied to the engine, fuel mixture, amount of oil burned, etc., etc.
I am faced with that problem now as I have modified a 215 cu in V-8 Olds I am installing in an MG. Low RPM detonation can be heard as the pinging noise on acceleration. However high RPM detonation is very hard to hear. So I have purchased a MSD knock sensor system that gives me an LED display of detonation. I have installed a direct ignition system and it has a ignition advance control that is mounted inside the cockpit. So I can change the amount of ignition advance while driving under different conditions and thus I will be able to set the timing at the optimum advance without getting into detonation.
Even though you have a cam, you should set your ignition timing at factory specs. Not until you get all the bugs worked out should you think about advancing the timing to gain power.
Howard
