23Racer

Just a question on first principles with the Megasquirt. My Crew Chief, Dave and I have the car running quite well. What we have found is that to get the car running well the timing on our Timing MAP seems correct using a 65 degree lead, but it has little correlation to the timing marks on the crank pulley. If we adjust the timing to get about 18 degrees BTDC on the Crankshaft pulley (we run it all at 18 except for starting at 25) using a timing light, the car acts like we have retarded the timing a ton. Its very soft and the oil and water heats up too fast. To get it to the timing marks on the eccentric shaft pulley would mean that we have to retard the timing by over 30 degrees and it won't run well there. To get the car to start again we have to advance the timing back to the original point about 40 degrees advanced from the Leading 1 5 degree BTDC timing marks.

If we return the timing to where Dave has it on the Timing MAP and the car works the best, the timing light flashes on a point about 40 degrees advanced from the marks on the pulley. I know I am missing something fundimental here. Is the S4 crank pulley wrong for an S5 Eccentric shaft? Does the Megasquirt trigger for the wasted spark fool the timing light or what? Ideas would be a big help as the car runs well, but I have no way of confirming what the actual timing is independent of the Megasquirt timing MAP.

If the timing actually was that far advanced compared to the timing marks on the crank pulley (I am talking at least 2 inches advanced) my understanding is that the car wouldn't run and would detonate like a pig. If the CAS was plunged one tooth off, it should still flash close to the timing marks if the Timing MAP compensated for that, wouldn't it?

Ideas?????

Eric

muythaibxr

If the engine doesn't run right with the timing where the marks are, then I'd say the pulley is installed wrong. Assuming the CAS and the settings for triggering are correct, spark should fire very close to where you set it, and spark on the MS should match the marks on the engine.

If your timing light has a dial on it, then set the dial to 0. It's not going to be accurate if you use the dial unless it specifically says it'll work with 2-stroke engines or wasted spark.

Ken