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2007 350, carburated

2

2wind

Member
Installed in a trolling boat, plugs foul after 20 hours. Book shows the timing at 26 deg @ 4000 rpm witch calculates to 4 degrees at idle. should'nt the timing be 8 to 10? are 41-993 the correct plugs?
 
The initial timing should be stamped on the serial number plate (owner's manual, too).

Have you checked the timing? Been on-going or recent occurence?
 
The plugs on my engines (454 CIDs) were fouling every 30 hours. Some of the plugs would be wet when removed and black. When I tied the choke with a twist wire from a loaf of bread I have not fouled a plug since. You might notice a thread or two about this process. The acceptance is mixed. I think the issue is that this is a bandaid and does not resolve the root cause. So when you need the choke it will not be readily available. Using this stop gap procedure may at least help in the diagnosis of the problem. It does not seem to be a rare event at least among older engines.

Chuck Hanson
 
I checked on the plugs.....seems nobody has a clear path to what the "correct" plug is. You can always try a Crusader dealer.

Based on a little looking, a set of MR43LTS would be viable. Another choice would be NGK's TR5 or TR55 depending upon the gap needed.
 
The 41-993 is the replacement for the discontinued (by some reports) 41-932. Both of these part numbers are for "double platinum" plugs. The MR43LTS is a "conventional" plug.
 
I would not think them worth the money if you replace them every year, but their design life is 300 hours...I pulled the OEM 3 season old set (41-932) out of my MERC and they still looked good.
 
Unless you have the coil packs that fire two plugs at once, double plats are not needed. if you want the "longevity" that platinum provides, it is only needed on the ground electrode.

Last time I checked, 300 hours was a season's worth for a boat that see frequent use. With the current pump price, I doubt many of us see that time accumulated in a year anymore.
 
I run about 600 hours a year, Just rebuilt the carb, again..(idelbrock 600) we did lean the choke a couple notches, it was opening though. Where did you set your timing?
 
You need to set the timing so you have the 26 degrees, BTDC, at 4000 rpm, like the manual states.

You have the Edelbrocks? I thought they came from the factory with holley's.
 
So the plug fouling has been an issue since the engine went in (either carb) or since the carb was switched?
 
Since the install, switched carbs trying to fix the fouling. Holleys have weak power valves. Thought that was the issue initially
 
I dont have an issue with the timing, its 26 at 4k as the book states. It will run better if I advance it though, most of my boater friends, (shade tree's) think it needs to be advanced to 8 - 10 at idle.
 
makomark said:
Think I'd get the timing issue straightened out before chasing anything in the fuel system.
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+ 1

2wind said:
I dont have an issue with the timing, its 26 at 4k as the book states. It will run better if I advance it though, most of my boater friends, (shade tree's) think it needs to be advanced to 8 - 10 at idle.
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Unless your friends have Marine Engine Ignition experience, I'd steer clear of their input.
No offense to their knowledge in the automobile area!
But leave the car guys to their cars.
Things are quite different with the more constant marine engine loads and potential for Detonation!

Does your ignition system require you to access a "BASE" or "Initial" advance mode when setting this?
 
I've got the same engine and have had the same run around with timing info. The plugs are mr43lts per crusader because I called them about mine. I also ditched the holleys for edelbrocks. My problem in my post about prop pitch could be related to fully advanced timing. Nobody says what timing at idle is for this engine, only at 4000rpms which scares the heck out of me. My latest mechanic set both of mine at 12 at idle. So 4 certainly doesn't sound right, I don't foul plugs, but I run too rich. My efficiency is dissapointing so my timing could be wrong too.
Steve
 
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