Marinette Boat Forum

Spark plugs in the front cylinders are fouling quickly. Plugs in the rear cylinders are burning clean.

I have Edelbrock 1409 carbs and original intake manifolds. The Carter carbs did not have any spacer under them so I didn't think to use one when I put the Edelbrocks in. Edelbrock suggested a 1 in four hole phenolic spacer and I put that on both engines. That may have changed the fouling from #1 & 2 to #1,2,3,4. Dramatic difference in the rear four cylinder plugs staying clean. Both sides of both engines identical results. I did step down the primary jets on one engine and don't notice a difference.

I cruise the Erie Canal and Lake Ontario. Lots of idle time in Canal cruising but I've just done a few open water trips of 4 to 6 hours at 2200 rpm with the same result. Checking and changing plugs after each trip. I believe I've eliminated any idle mix questions.

I don't know what could be the possible causes of this and the guys at Edelbrock have no further suggestions. Any ideas would be welcome.

Is this a vee drive application? (Probably not, but I'm at a loss otherwise!)

Jeff

No. The trans is on a bell housing directly behind the engine.

Hopefully I am making progress. I cruised yesterday for several hours. Started with all clean plugs. I advanced the port engine timing to a little beyond the normal range, both initial and mechanical advance. On the Starboard engine I took the carb spacer out and cut away the dividers between the four holes.

The advanced timing on the Port engine didn't help with the fouling on the front cylinders. I had some noises at 2400 rpm and finished the cruise at 1800 rpm. All the plugs on the Starboard engine are clean!

This afternoon I'll back off on the timing on the Port Engine and chop out the spacer dividers. Taking a longer cruise tomorrow.

It worked.

This was a rough modification with a hacksaw. I'll get the Edelbrock version with proper smooth sides. $27. My son says smooth is good.