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Misfire diagnosis
#1
Hi All,

As a newbie to Sevens I need a bit of help. My car shipped to the US over Christmas and I've sorted a few things out, but only had the opportunity to start it on Sunday,  a nice warm(70 F.) day. I put in fresh 87 octane non ethanol fuel. It wouldn't start so I looked at the obvious. I tickled the carb to make sure I had fuel(it is a Solex 30 MOV). I pulled the dizzy cap and found the rotor had a bit of burning so I cleaned that up. There were also some brass flakes in the dizzy which I blew out. The points looked good. It still wouldn't start so I pulled the plugs(two NGKs and two French Champions). They were all sooty. So I changed to a new set of Champions. The engine started easily but was running running rough, hunting. I drove it for about 15 minutes and the car had no power and wouldn't rev past 3500. When I got back, I pulled the plug wires and confirmed I was getting spark on each. No. 1 wire came loose from the blade connector when I pulled it, so I will resolder. My inclination is that there are two issues. One may be the No. 1 plug wire which may be causing the misfire. But the sooty plugs on 1 through 4 would seem to indicate a rich mixture. The car was apparently running fine in the UK in December so I'm at a loss as to what might or might not have changed.
I'll check the carb main jet to see if it is seated well. I also ordered new plug wire and blade connectors to make sure that isn't the issue. Rotor, condenser? In past engine experience a bad condenser would manifest on load, but not at idle. All this, including the sooty plugs, would seem to indicate a mixture which is too rich. A sunken float perhaps?

Any help is greatly appreciated. (Sorry for the long post)

Erich in Seattle
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Messages In This Thread
Misfire diagnosis - by Erich - 14-03-2018, 02:08 AM
RE: Misfire diagnosis - by NickB - 14-03-2018, 02:58 AM
RE: Misfire diagnosis - by Erich - 14-03-2018, 03:49 AM
RE: Misfire diagnosis - by Chris KC - 14-03-2018, 09:50 AM
RE: Misfire diagnosis - by John Mason - 14-03-2018, 02:07 PM
RE: Misfire diagnosis - by Erich - 14-03-2018, 03:26 PM
RE: Misfire diagnosis - by John Mason - 14-03-2018, 06:13 PM
RE: Misfire diagnosis - by Michael - 14-03-2018, 06:31 PM
RE: Misfire diagnosis - by Colin Wilks - 14-03-2018, 07:08 PM

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