| len47merc | -- 12-20-2015 @ 6:17 AM |
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Gents - need some troubleshooting advice. Took the '47 59AB out for a family Christmas light cruise last eve and for the first time noticed a low rpm/high load miss. Motor and carb are fundamentally new (<3,000 miles, 115+ psi all cylinders)) with all new or rebuilt electricals. Distributor was set up on a Sun machine. Has always ran great with excellent power and especially torque, so much so that I often both shift into 3rd on flats at 20 mph and take flat and/or downhill 90 degree corners without shifting out of 3rd - the motor just presses on smoothly. With the 3.78 rear the car has performed very well in 3rd here in the NC hills with little to no shifting out of third necessary at low-to-moderate rpms. Last night with crisp sub-40 ambient temps and a warm motor, upon leaving the neighborhood and turning up the relatively steep hill I routinely run up in third gear at 25 mph, the motor for the first time exhibited misses when pressing the car to accelerate in 3rd up the hill. It has never done this this before. Shifting down to 2nd and/or pressing less firmly on the gas pedal to accelerate - this miss disappears. When leaving the first stop I shifted into 3rd at 20 mph on a flat road and attempted to smoothly, with a bit more gas pedal than normal, accelerate and the miss(es) is/are consistently there. Again, letting off the gas a bit and pressing less hard under these conditions the miss disappears. If I run the motor up to higher rpms (1,500+) before shifting and press the gas harder to accelerate in third, at the higher rpms the miss does not show itself. I can make it happen in 2nd as well if I choose to shift at a very low rpm and try to accelerate from the low rpm. The miss is very similar to that I've seen in other cars (not necessarily EFV8's) with something breaking down electrically, such as a spark plug wire or cracked distributor cap, etc.. This is new for this motor. Again, it runs great as it normally does except under low rpm / high load situations. Fuel mileage has not changed btw and is in the expected range. Upon returning home I opened the hood in the dark and ran it up 2,500 - 3,000 rpm but could see no arcing anywhere on the motor. Checked the original-style plug wires and they all are tight. Pulled the plugs this morning and they all are burning a medium gray. Before I go through any further trial-and-error adjustments and/or replacement of parts I'd greatly appreciate some sage troubleshooting process advice that may more quickly and cost effectively identify the root cause. Thanks in advance - This message was edited by len47merc on 12-20-15 @ 6:19 AM
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| Pat's 52 | -- 12-20-2015 @ 6:31 AM |
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I had similar problem with my recently rebuilt 50 Ford convt. I took top off carb and found black dirt in bottom. I cleaned it out and replaced stone filter in fuel bowl with Wix paper filter. Seems to have taken care of problem. I will check gas tank to determine if that is the cause. Just a thought because I did similar checks that you did. Good luck and Merry Christmas!
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| len47merc | -- 12-20-2015 @ 6:49 AM |
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Thanks Pat's 52 - for me the fuel tank was removed, cleaned and sealed upon car receipt and fuel lines were also thoroughly cleaned and/or replaced. I will go to this step (checking the bowl filter) in a progressive manner from easiest/quickest to more complex after seeing additional thoughts. Very good suggestion - have to admit my current paradigm has me so focused electrically (given prior experience on other vehicles exhibiting similar similar behavior) that I've given little-to-no attention to fuel considerations thus far. Steve
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| TomO | -- 12-20-2015 @ 8:23 AM |
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Steve, I'm inclined to believe that the problem might be electrical also. I suspect that the condenser may be breaking down or your ignition resistor is not making good contact at the rivets. Tom
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| len47merc | -- 12-20-2015 @ 10:28 AM |
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Thanks Tom - cleaning the plugs now and about to post a separate thread on them with a photo. The condenser you are referring to is that located on the distributor - correct? I've never had one breaking down under load only and work well otherwise - they've always been either all good or all bad with no in-between. Perhaps this will be a first - I'll try that after cleaning and re-gapping the plugs (see new thread I am about to post on this). Question - by 'ignition resistor' assume you are referring to the resistor under the dash - ? Feel stupid having to ask that question. EDIT - also Tom, does a method exist beyond straight replacement for the condenser and/or resistor that will confirm they are good/bad? Thanks - Mon, 12/21 EDIT - gapping and installing a new set of plugs today and as well resetting mixture screws with a vacuum gauge (ref other thread on 59AB spark plugs color). Will give this a go as a first step. Will advise of results. Steve This message was edited by len47merc on 12-21-15 @ 7:28 AM
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| TomO | -- 12-21-2015 @ 8:24 AM |
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Steve, a weak spark shows up first under load. The insulation between layers of the condenser foil, can begin to break down and change the value of the condenser causing a weak spark. Usually the spark will change color from a nice blue to orange or red when the spark becomes weak. I have also seen cold soldered joints on the grounding tab of the condenser cause this problem. The ignition resister is is the one under the dash and is checked by checking the voltage at the input to the coil with the points open and closed. Open points should show very close to battery voltage, closed points should show around 4 volts. You should also check your dwell for 34-36 degrees. I replied to your other thread. Tom
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| cliftford | -- 12-21-2015 @ 11:07 AM |
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Here is something we all know but we need to remind ourselves of from time to time: A fuel problem often mimics an ignition problem, and vice versa.
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| len47merc | -- 12-21-2015 @ 12:15 PM |
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Thanks Tom & cliftford - Steve
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| oldford2 | -- 12-21-2015 @ 12:27 PM |
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My 2 cents worth because I had this happen a few years ago: Dirt in the main jets. Easy check to pull the jets and inspect.
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| len47merc | -- 12-21-2015 @ 1:23 PM |
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Ok guys - 'splain something to me. Taking it one step at a time so as to not introduce too many variables at one time, removed as stated above the plugs with ~3,500 miles on them and installed a new set of freshly gapped plugs (.025"). Cranked/warmed it up and just drove it 20 miles with multiple stops & starts. Shifted into 3rd multiple times at 10 mph and pressed it to accelerate up hills and on flats. Took several 90 degree green light turns without shifting out of 3rd and accelerated harder than usual back up to speed. No miss - no buck. Tried several times under heavy uphill low rpm 3rd gear loads and no miss. . So apparently one of the relatively new plugs (for my more 'modern' expectation) was breaking down. They were all clean as a pin so which one I don't know. The question is how long/how many miles should a set of original style copper plugs last before cleaning/changing is required? What are your sage expectations and experience in this regard? The plugs look too clean and the age/mileage too low IMHO to have to be dealing with this already but this also is my 1st EFV8. And/or are Autolite 216's the problem? Appreciate your thoughts here. Thanks - Steve
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| oldford2 | -- 12-21-2015 @ 1:30 PM |
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My 2 cents worth because I had this happen a few years ago: Dirt in the main jets. Easy check to pull the jets and inspect.
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| TomO | -- 12-22-2015 @ 6:44 AM |
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I had Champion H10's that did not last very long before my engine developed a miss and then I switched to the 216's. I have about 1,500 miles on the ones in my Lincoln without a problem. My 40 has Champion RJ-14-YC and I have about 6,000 miles on them. I changed to them because Supereal recommended them. They project a little further into the chamber than the Autolite 216 or the H10. Another recommendation is the NGK # B-6L. I haven't tried them. No one around here carries them. See if you can find someone with a spark plug tester and test the plugs. I suspect that they are dong the same as the Champion H10C did. The seal between the porcelain and the base was bad on 4 of the 8 H10C plugs that I had on my 40. Both the Autolite and Champion plugs are for "industrial" use and may not be up to handling the heat and compression of the flatheads. If that is the case, my Lincoln should show signs of problems this summer. It has a higher compression ratio than the flatheads. Tom
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| len47merc | -- 12-22-2015 @ 9:56 AM |
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Thanks Tom for sharing your experience here - that's very good feedback and info to have. Given my expectation surrounding the plugs was to realize 15K-20K miles minimum I really never expected them to be the root cause on this. Taking the old ones over to have them checked this afternoon - let you know what I find. Good luck with your set of 216's - hopefully my experience thus far is just an isolated case. Steve
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| ken ct. | -- 12-22-2015 @ 2:20 PM |
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Tom O ,,check a motor cycle shop (not a Harley d. ) one. most jap bikes use all kinds of NGK's. ken ct.
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| len47merc | -- 12-28-2015 @ 5:53 AM |
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Tom - following-up - under load the seal between the porcelain and the base on the #2 cylinder Autolite 216 plug was bad fyi. I note also this particular plug with ~3,500 miles is two+ years old and as a result of the NC humidity exhibited a fairly obvious (and the most pronounced of all the plugs) rust stain on the porcelain around the top of the base as well. The car is kept in an very dry attached garage and never sees rain, but during extended wet periods here in NC the humidity shows itself on the plugs' bases. Not sure if that was the root cause or contributor, or if the plug was bad and just took a while to show itself, or if, as you suggest, the 216s just can't handle the heat and compression of the flatheads. New set continues to perform well btw. Steve
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| Pat's 52 | -- 12-28-2015 @ 1:57 PM |
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Steve, what new plugs did you go too? The Champion RJ's or the NGK's. I'm curious because I have the Autolite 216's in my 50. Thank you! Pat
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| len47merc | -- 12-29-2015 @ 5:26 AM |
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Pat - One would have thought I'd change the plug brand but given how clean and unscathed the business end of the plugs were, how positively and well they have performed for the last couple of years/3,500 miles, and the Autolites just happened to be on sale for $1.49 each locally when a new set of plugs was needed, I made the decision to give them one more chance. Had multiple plugs been found to be bad I would have gone with the RJ's based on Tom's experience and supereal's recommendation, but as only one was at issue I've given the Autolite's the benefit of the doubt for the time being and assumed the bad plug was a 'flier' that may have been dropped, etc.. I will report back on results. While I run NGK's on most all my modern daily drivers I'd have a problem running anything beyond the Champion RJs or Autolite 216s on the '47 for no other reason than the principle of the thing. My gut tells me I'll be switching to the RJs in ~2017 (3,000+ miles) but hopefully my gut is wrong - usually it's not so suspect I'll be subconsciously and consciously monitoring every low rpm acceleration from now on. Steve
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| 40 Coupe | -- 12-29-2015 @ 5:49 AM |
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When you had the distributor set did you install new rotor and new inner distributor caps? The two parts have a maximum gap. As gaps (resistance) in the ignition system increase, the ignition coil has to work harder and produce higher voltage to jump the gaps. Once one part of the ignition circuit resistance becomes excessive miss-fires present themselves. How about the plug wires are they solid wire or higher desistance carbon? Replacing the plugs will decrease the resistance for a while but if the problem re-occurs shortly look elsewhere in the system. NAPA sells NGK plugs and can order them from the local warehouse overnight. This message was edited by 40 Coupe on 12-29-15 @ 5:51 AM
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| ken ct. | -- 12-29-2015 @ 6:02 AM |
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Steve I would go through that dist and converet it to a crab style with new rotor,cap,rubber cap nipples, and clips and check points real good. I can do this for you very reasonable or send you the parts to diys if you want. Have done many in 25 yrs. Much simpeler setup.Use copper or steel cored wires. ken ct.
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| ken ct. | -- 12-29-2015 @ 7:44 AM |
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Steve check your PM's ken ct.
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| len47merc | -- 12-29-2015 @ 8:24 AM |
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Thanks for the heads-up on the PM Ken - fyi I replied. Steve
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