retarded ignition

[neilmac]

would it be possible to use the mjl with a starting position of less than 5 degrees static timing? I am considering using one for sporting trials. At the moment I am using a Honda 1330cc with 1.750" s.u. carb and a static timing of 3 deg. btdc and obviously cannot get enough advance using a dizzy. I need the retardation to run the engine down to very low speeds as we regularily use less than 500rpm. I would appreciate any views.

[Paratime]

Yes, you can set the base timing to less than 10, the MJLJ will still function.

[KITT]

I don't think MegaJolt can control it once the revs are below 500rpm. I think the EDIS takes over and is fixed at 10 degrees. I could be wrong, but the software certainly doesn't let me specify a value below 500rpm.

regards

Matt
http://www.cate1.co.uk/megajolt/

[Paratime]

I'm sorry, what I meant was, the EDIS will run the same if you set the base timing to a value less then 10 BTDC.

[neilmac]

do you mean that the eidis can be "cheated" by simply setting the actual sensor at a retarded position for example at 10 deg. ATDC. so that the base position will actually be TDC. or am I getting the wrong end of the stick.

[Paratime]

That is correct. The EDIS sets the base timing at 10 BTDC when the sensor is placed in the correct location in reference to the missing tooth, at TDC. (this location varies for different numbers of cylinders) If you move the sensor a few degrees before or after this "correct" location, the base timing will be a few degrees before or after 10 BTDC.

[neilmac]

well thanks very much for clearing that point up for me.Incidentaly does anyone have an opinion on what I might be better using, the map or the tps. at low revs the carb.piston damper can sometimes be heard to shunt if the damper oil gets low. But my type of use is to pull the revs down on a very small throttle then controling it with tiny inputs gently to chug like a steam train before revving up as hard as the motor will go. Two not very compatible scenarios.

[dermot]

Well my own totally untested <opinion> would be that MAP is best, but you need to be sure you have a good MAP pickup point, if it's single carb engine that helps, you'd want to minimise pulsing in the tract....perhaps a 'neck' in the vac. pipe would be needed? (smooths the flow).

-D

[rmccomiskie]

The EDIS documentation says that it will fire from 57.5 degrees BTDC to 10 degrees ATDC (64 us - 1792 us). The only time it defaults to 10 degrees BTDC is when there's no SAW activity for 5 ignition events. So, if the MJLJ is sending the right pulsewidth, the EDIS should fire all the way to 10 degrees ATDC.

I'm interested in this as well. Aircraft engines are often started at about 5 degrees ATDC to prevent the propeller from kicking back. Easier on the starter and battery too.

Bob.