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Petronix Ignition Merc 350 Possible Issues

wellcraftnova230

Contributing Member
"Hello All,
So two years ago


"Hello All,
So two years ago I decided to upgrade my boat with a Petronix Ignitior II ignition system and a Flame Thrower II coil. The engine ended up being very hard to start and it would stall nearly every time i pulled it out of gear (I have an alpha drive). I took off the flame thrower coil and replaced with new stock coil. Now it only stalls periodically when coming out of gear and is hard starting when cold. I have had the carb rebuild and have adjusted the idle screws too many times, I think it is about as perfect as it can be. The cap was only 2 years old and the terminals were already burnt up as if it was 5 years old. Does anyone think possibly opening the gap on the plugs from 0.035 to 0.045 will solve my issue? I also need to fart with my choke too but I have tried manually closing/opening it and the engine still seems a little hard to start. Shift cable was replaced 2 years ago. I am thinking about switching back to points to see if that will help at all. Please advise, thank you"
 
"Jon:

What is the timing se


"Jon:

What is the timing set at now?

Does the choke close when cold all the way except 1/8"? Does it open all the way when the engine is hot?

If you have a 2BBL Mercarb, did you use the 1/4" thick carb base gasket? Very important for best fuel/air atomization.

Is the shift interrupt switch working properly?

How old are the ignition wires? Is there a gasket under the rim of the dist. cap?

Let us know what you find."
 
"Hello Guy,

The timing is s


"Hello Guy,

The timing is set at 8 degrees from TDC. I would have to look more into the choke when I run the motor. Where do I measure the 1/8" from? It is a 4bbl Rochester carb. The shift interrupt switch was replaced with a NOS switch last year. The wires are 2 years old. There is a gasket under the cap. Any more suggestions? My thoughts are it is either the choke is out of wack, which may be part of the problem, and maybe plug gap? Please let me know. Thank you all very much!"
 
"Where do I measure the 1/

"Where do I measure the 1/8" from?"

When I set up a 2 BBL carb I insert a 1/8" drill bit (w/a BIG piece of duct tape on the drill end to use as a handle and to keep it from falling into the carb) between the edge of the carb throat and the choke plate so that they just meet when turning the black choke assy. This procedure may work on your carb; not sure.

I read up on setting up your carb. There is more to it than can be explained here. Since you have a 4BBL carb there will be 2 mixture screws to adjust. You may have to readjust each screw when it is idling. The tuneup specs call for AC R42TS spark plugs w/a plug gap of 0.035" and timing is 8 deg. BTDC. I would put in a new set of spark plugs to start.

When the engine is cold the choke should close when the throttle is moved. After it starts up the choke pulloff should open the choke plate a small amount. It will continue to open if working properly as the engine warms.
 
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