carguy | -- 10-15-2010 @ 8:57 AM |
My '34 has never run well. Starts and idles OK but no power. Good compression but regularly the plugs in cylinders 1,4,6,7 are fouled and shorting the spark plug wire for these cylinders to ground at idle shows no change. 1,4,6,7 are every other cylinder in the firing order and these 4 cylinders are fed, according to the Service Bulletin, voltage from the same tab on the rotor. At this point I'm assuming that the rotor is somehow defective. I am asking for comments from folks who understand this ignition system better than I about my assumption and suggestions for a fix. The distributor was sent out to be rebuilt. Should I send it back or ????
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supereal | -- 10-15-2010 @ 10:15 AM |
Yes, it could be a defective rotor, but also look at the cap on that side of the distributor. If the cap was replaced, it may not fit properly. Many repro distributor parts require careful fitting to the body of the unit to preserve the gap between the rotor tip and the plug wire contact by filing the edges, and some we have seen hardly work, if at all. Both sides share the points, condenser, and rotor bushings. As your problem seems to be limited to one side, and all plugs there are affected, a carbon path problem seems unlikely unless there is one on the rotor, itself.
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carguy | -- 10-15-2010 @ 12:48 PM |
Thanks for the info. I am having the problem with cylinders 1,4,6,7 so it is, in fact both sides. I have no problem with throwing more money at the problem so do you recommend that I replace the rotor, and both inner and outer distributor caps or should I send the whole thing back to Skip and have him refurbish it again? I'm a bit concerned about the quality of the new parts.
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drkbp | -- 10-15-2010 @ 6:04 PM |
carguy, 1, 4, 6 and 7 run off the back tab of the rotor as others have already said. There is a small slot in the distributor housing that the caps should fit down into. I would undo the bail and be sure the caps are down in the slot properly. If not, they will be lifted away from the rotor on the back side contact points and the cap covers will also be lifted away. The caps are the same for both sides and have the numbers for both banks on them. If that doesn't get it, I would drop the distributor out and be sure the rotor is very clean at the rear tab. Hope this helps, Ken
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supereal | -- 10-16-2010 @ 9:23 AM |
I was referring to the sides of the distributor, not the engine. Ill fitting caps are becoming common. The clearance of the rotor tips to the cap terminals is critical for proper operation.
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Keystone 34 3w | -- 10-16-2010 @ 2:45 PM |
Carguy, don`t overlook the possibility that the carb on the rh. barrel side could be too rich and fouling the four plugs. The 34 intake is a dual plane design and each of the two barrels feed four cylinders. If the main jet is loose on the right side, this would allow too much fuel to feed the cylinders you describe. If you say it idles fine I would think that you have spark on all eight. Also the leaner the mixture the more power you get.
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40 Coupe | -- 10-17-2010 @ 8:12 AM |
I sincerely doubt your car would start on only 4 cyl. so you must be getting some spark to all of the plugs. I too suspect the carb has a problem. With the car running at idle pull one plug wire at a time and place it close to the block to see if you can get an even spark to jump on every plug wire. then place the spark plugs in 1 into 2 and see if this makes a difference or the problem is still on #1 do this with every cyl with a problem, and you can eliminate the spark plugs. If the problems stay put then turn your attention to the carb.
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40 Coupe | -- 10-17-2010 @ 8:13 AM |
I sincerely doubt your car would start on only 4 cyl. so you must be getting some spark to all of the plugs. I too suspect the carb has a problem. With the car running at idle pull one plug wire at a time and place it close to the block to see if you can get an even spark to jump on every plug wire. then place the spark plugs in 1 into 2 and see if this makes a difference or the problem is still on #1 do this with every cyl with a problem, and you can eliminate the spark plugs. If the problems stay put then turn your attention to the carb.
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carguy | -- 11-12-2010 @ 6:44 PM |
Here's a follow-up on this. Those who suspected the carb to be the problem were right. I checked the spark and had a strong 1/2" arc with every wire when put close to a head bolt. Skip suggested that I send my carb to uncle Max for a rebuild. I did this and also purchased a new '97 so I would be sure to have a good carb and a good backup. My '34 now runs like it should. Thanks to all who responded.
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Keystone 34 3w | -- 11-14-2010 @ 9:40 PM |
Carguy, Its nice to see that your car runs fine now. Having driven three seperate 34s over the last 23 years gives an owner a hint of little issues that can arise. Did you ask the rebuilder what was found as cause for being too rich on one side (like loose jet or emultion tube)? I have seen this before and am just curious about your cause.
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carguy | -- 11-15-2010 @ 1:24 PM |
Keystone, Max told me that one of the high speed air-bleeds and both of the emulsion tubes, along with one idle jet were clogged solid, as well as a lot of mineral buildup in the enrichment circuits. I hope this means something to you. It's way above my pay grade. {:^) I will say that the rebuilt carb looks almost like new and performs flawlessly.
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supereal | -- 11-15-2010 @ 2:03 PM |
Most of the deposits found in carbs consist of varnish produced by the evaporation of fuel, and rust/dirt from an aging fuel tank. "Minerals" suggest something else to me. We haven't seen a completely clogged carb such as described unless the car sat for a period of years and the casting deteriorated. In any case, I'd install a good in-line filter to catch any crud in the tank, and a dose of a fuel storage protector to reduce deposit formation.
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carguy | -- 11-15-2010 @ 3:48 PM |
Thanks Supereal for the suggestions. In my past frustration with my problems I installed a new tank from Drake fearing that my original tank was contributing to my problems. I now do run an inline filter prior to the pump and a glass bowl type filter between the pump and the carb. And I'm a big believer in fuel stabilizer, particularly with today's fuels
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