Alright I had always heard to gap the digital ignition coil 28 to 35 thousands.
Never knew why, think I heard "it screws up the timing" and of course "it will rub".
I checked mine it was at 28 to 30 thousands on my gx390. Put the cover fan shroud back on with 3 of the 5 screws.
Then I drew a black dot around where I thought TDC on the fan would be and drill started the engine. Quickly found the black dot on the fan cover with my old timing light, marked the shroud adjacent to where the moving dot was at 4,000rpm. Took the cover back off moved the ignition coil all the way out about 65 to 70 thousands of an inch.
Reinstalled everything and fired it up. My idle is 2,000rpm because it's a pressure washer and is always under load, idle was almost in the same place, maybe 1 degree different. Throttling it up it was definitely jumper.
I throttled it up to 4,000 and it was 4 degrees more advanced according to my light. But there was still more throttle. Before with stock timing I could hold the governor wide open and it was 3,950rpm plus or minus 20 using an overly restrictive nozzle. With 4 degrees more advance it was able to power past the previous run, bouncing off the rev limiter, at about 4,140rpm so the timing definitely was heading the right direction.
To go from 2,800psi at 4.4gpm to 2,900psi at 4.5gpm takes about a half horsepower more. And it was bouncing off the rev limiter so it had to be worth at least an additional half horsepower.
Never knew why, think I heard "it screws up the timing" and of course "it will rub".
I checked mine it was at 28 to 30 thousands on my gx390. Put the cover fan shroud back on with 3 of the 5 screws.
Then I drew a black dot around where I thought TDC on the fan would be and drill started the engine. Quickly found the black dot on the fan cover with my old timing light, marked the shroud adjacent to where the moving dot was at 4,000rpm. Took the cover back off moved the ignition coil all the way out about 65 to 70 thousands of an inch.
Reinstalled everything and fired it up. My idle is 2,000rpm because it's a pressure washer and is always under load, idle was almost in the same place, maybe 1 degree different. Throttling it up it was definitely jumper.
I throttled it up to 4,000 and it was 4 degrees more advanced according to my light. But there was still more throttle. Before with stock timing I could hold the governor wide open and it was 3,950rpm plus or minus 20 using an overly restrictive nozzle. With 4 degrees more advance it was able to power past the previous run, bouncing off the rev limiter, at about 4,140rpm so the timing definitely was heading the right direction.
To go from 2,800psi at 4.4gpm to 2,900psi at 4.5gpm takes about a half horsepower more. And it was bouncing off the rev limiter so it had to be worth at least an additional half horsepower.
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