1969 Chrysler 70hp Fouling Plugs

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bwhit05

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Jul 15, 2013
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New to me boat, 1969 Chrysler 70hp, new plugs (NGK BUHW-2) beginning of boating season which for me was Memorial Weekend. Ran fine all that weekend. Next use, forth of July ran fine, maybe 2 to 3 hrs of total use between the two weekend. This past weekend we took it out and about a half hour into the ride, the motor started to miss fire. I stopped and pulled the plugs and they where covered with carbon. Switched with new set of plugs and that did not fix the issue. Starts fine, idles a little rough and spits and sputters underway. The extra set that the previous owner had were a little different than what was in there NGK BUHW without the -2. Any thoughts?

Brian
 
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foodfisher

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Feb 18, 2009
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3,756
Re: 1969 Chrysler 70hp Fouling Plugs

Check your manual and use the recomended plugs
 
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bwhit05

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Joined
Jul 15, 2013
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Re: 1969 Chrysler 70hp Fouling Plugs

BUHW-2 were the proper plugs according to marine mechanic. What could cause them to foul so quickly (2 to 3hrs of total use)? I'm running a 50:1 mix. Technically it is 48:1 because of the simple measuring 6gallon gas can 16oz oil. Could that little bit cause a plug to foul?
 
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foodfisher

Captain
Joined
Feb 18, 2009
Messages
3,756
Re: 1969 Chrysler 70hp Fouling Plugs

If you intend on keeping and using an engine that is 44yrs old, the best money you could spend is on an OEM manual. The refered to mechanic was "probably" not even a glimmer in his fathers eye back then. Be self relient and save $. Slow running aka trolling will foul plugs period.
 
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