Will a 3.0 run on 1 spark plug???

Rod Burton

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Jul 11, 2011
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First post in awhile. Thanks in advance.
I been rebuilding a 67 Starcraft Holiday with donor engine from an 89, 140hp, 3.0. I've replaced all ignition and external accessory components except for the points. I'll be doing that now. My question comes from a real mystery to me, but the engine was running great. I took it to Cumberland right out of the shop where I had some timing (confirmed) and points (sanded) issues resolved. It was running great. Got it in the water. Would not start. After 20 minutes it finally started. It was rough to begin but smoothed out. Running a bit rough still but got it to plane. I got about a 1/2 mile down and it stalled. Got it started back up and it was really bad this time. At full throttle (50 rpm) I was getting about 15 mph. Limped it back to the dock, loaded and when home. I got the hood off of it yesterday. I did not mess with it prior too, and 3 of the spark plug wires were disconnected. How is this possible? So will an engine run with one wire connected to the distributor? I just need to know that I'm not crazy here because I touched nothing. My plan was to replace the points because everything else is new. Plugs, wires, condenser, button, and coil. Starter, fuel pump, and alternator too. So can someone help me answer this question? Thanks again.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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The wires were probably not seated. and yes, a motor running at some speed can run on a few cylinders. it wont run well. V6's and V8's will run on as little as two cylinders.
 

Rod Burton

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Can anyone else provide some feedback on this topic. I'm still puzzled about how a 3 liter engine can start, run and stay, running, with one spark plug. I've worked on 3 liter car engines and I can't figure out how it could run. Thanks in advance.
 

nola mike

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I mean, if you were running on one cylinder sounds like you answered your own question?
 

garbageguy

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I would think - no, not on 1. My guess would be that there was some intermittent electrical connection (as mentioned above) when it was running
 

airshot

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If three wires were off then all were probably loose making intermittent connections until only one was left. No way should a plug wire fall off unless not properly installed to begin with...
 

cyclops222

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Bad mechanic keeps you coming back for another BIG BILL.
You need new points & condenser. Plus a Dwell Meter from some auto places like Harbor Freight.
 

rolmops

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It is probably time to get rid of your points and install a Delco EST Marine Kit. No more messing around with worn or wet points and very precisely timed ignition.I did it and it is just great
 

Rod Burton

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Bad mechanic keeps you coming back for another BIG BILL.
You need new points & condenser. Plus a Dwell Meter from some auto places like Harbor Freight.
Good advice. My dad said the same thing about the dwell meter.
 

Rod Burton

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Thank for all the advice. I think maybe the plugs maybe came off. Really weird but possible. I've just never heard of that happening. And yes, if there is a kit I can get to eliminate that variable. I will.
 

Bondo

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Thank for all the advice. I think maybe the plugs maybe came off. Really weird but possible. I've just never heard of that happening. And yes, if there is a kit I can get to eliminate that variable. I will.

It is probably time to get rid of your points and install a Delco EST Marine Kit. No more messing around with worn or wet points and very precisely timed ignition.I did it and it is just great
Ayuh,...... Welcome Aboard,...... That's the perfect "Kit",.....
 
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