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Old 08-06-2011, 02:56 PM
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Join Date: Mar 2010
Posts: 36
Misfire mystery

Hey folks,

Been a long time since I've posted here but always got good advice so I'm back for another round. I've just picked up a 1974 280 with the usual inline 6/Solex setup. It sat for 4 years in a garage before I got it. Supposedly ran fine when parked. Ever heard that before?

The car did lead a good life. Receipts for all sorts of work over the years. Little rust and no rust through, nice paint, good interior. Worth saving.

So, to the point. After an oil change, gas drain, new battery, it came to life. Runs but misses on cylinder one. That plug was heavily fouled with black goo. 2 thru 6 showed normal tan ashing. The number one wire was bad, so I did new plugs and wires (Bosch.) Thought that would solve it, but no...

Pulled the #1 plug and it showed a little black. Might have been a little gassed. Checked compression. 130. Same for the rest 125 or better. Note - the valves are making some noise and need adjusting. The engine runs with zero smoke. Receipts show rings done in 2002.

On to the distributor. No cracks, carbon fouled contacts and the rotor tip needed a little emery cloth. Not bad and it cleaned up well. No sign of trouble with the number one pin. Cleaned the points at the same time. Receipts for new points and carb rebuild around 2000.

So, I've got a plug wire that is sparking and I assume a sparking plug, but it comes out gassed and black. Good compression. Swapped the plug with another cylinder and no change. Pull a wire off of another cylinder when running and the RPM drops as expected, but not on number one.

I'm about to order a new cap and rotor, but thought I'd run this riddle by the crowd here and see if I'm missing something.

Thoughts? Thanks!

Eric
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1973 280 SE Project
1974 280C Project
1975 450 SL (sold, ruined by new owner)
1973 280 SE (sold, never should have)
2006 Dodge 2500 4WD Cummins (best ever)
1983 Land Rover Series 3 88"
1999 Land Rover Discovery 1 (wife's toy)
1968 Piper Cherokee 180D (most fun of all)
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  #2  
Old 08-06-2011, 04:09 PM
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Join Date: Dec 2009
Location: Northwest Ohio
Posts: 605
Try switching plug wire #2 to #1 cylinder, then pull both to check rpms. You might just have a bad wire.

edit:Sorry. Just noticed that the wires are new. Might try switching them just to rule it out. Otherwise I would say maybe you have a valve out of adjustment. The intake of #1 is where you measure the lift for chain stretch. Maybe someone forgot to reset the lash. Someone on my car must have done this, as the cam wore the camber right off the rocker.
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1981 300TD 310k miles
1970 280sel 172k miles
1966 230 Fintail 162k miles

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Last edited by Carpenterman; 08-06-2011 at 04:20 PM.
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Old 08-06-2011, 05:12 PM
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Quote:
Originally Posted by Carpenterman View Post
Try switching plug wire #2 to #1 cylinder, then pull both to check rpms. You might just have a bad wire.

edit:Sorry. Just noticed that the wires are new. Might try switching them just to rule it out. Otherwise I would say maybe you have a valve out of adjustment. The intake of #1 is where you measure the lift for chain stretch. Maybe someone forgot to reset the lash. Someone on my car must have done this, as the cam wore the camber right off the rocker.
Thanks for the thoughts. Yes, new wires and plugs, although I may not have the right plugs. I have checked/adjusted the valves. All were nearly dead on. Lots of slop in the distributor, so I think I've got some work to do there.

If I can get the Solex dialed in a bit, it will be a lot easier to work on. Grrrr....
__________________
1973 280 SE Project
1974 280C Project
1975 450 SL (sold, ruined by new owner)
1973 280 SE (sold, never should have)
2006 Dodge 2500 4WD Cummins (best ever)
1983 Land Rover Series 3 88"
1999 Land Rover Discovery 1 (wife's toy)
1968 Piper Cherokee 180D (most fun of all)
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  #4  
Old 08-06-2011, 09:43 PM
t walgamuth's Avatar
dieselarchitect
 
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 34,522
distributor cap is the next thing to suspect providing you have checked both ends of the connection for that cylinder....on the plug and at the cap.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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