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By Rono - 7 Years Ago
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This is a problem I have been chasing down for a while. Ever since I made a pass at the Winterport Dragway in Maine. #7 cylinder spark plug is wet with fuel, but compression is good (160 psi). The distributor has Pertronix Ignition. When I pulled the cap and rotor, the cap appears burned at all contacts. When I removed the rotor, I get a very slight side to side movement of the distributor shaft (maybe .005") but no movement when the rotor is sitting inside the Pertronix collar. The cap and rotor are 10 years old, but they don't have that many miles on them. So, do I try a new cap and rotor first before replacing the distributor?  Thanks, Rono
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By 55 GLASS TOP - 7 Years Ago
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Have you checked to see if you are getting spark to #7 cylinder or maybe the plug is bad
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By miker - 7 Years Ago
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If you've got a consistent timing reading with a light up till the curve tops out, I'd say the dizzy is ok. I've had a number of problems with caps and rotors showing signs like that. I've written it off to hot (mostly MSD) ignitions and coils, and cheap offshore caps.
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By Genuinerod - 7 Years Ago
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What kind of shape are the plug wires?
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By DryLakesRacer - 7 Years Ago
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IMHO Looking at the cap contacts, it appears that none of them have or show any arcing on the flat verticle area where you would expect it. It's on the horizonal contact area where the contact is meeting it at the Bakelite. There also appears to be burn/arcing on the top of the rotor contact. This shows me the rotor contact area is not in the center cap contact area which in my opinion is too high up into the cap. As I understand it, the rotor never touches the cap contacts but should pass by it at its verticle center. This can be adjusted by, in this case, bending the rotor contact down and filing it flat again (parrellel) to the to the verticle plane of the Distributor.
If you guys think I'm crazy tell me but I also have 1/8" holes drilled in my racing caps in the same plane as the rotor between each contact. I was a very high voltage electrician in my working life and know damage exposed corona arcing can do.
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By Rono - 7 Years Ago
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Thanks for the responses guys! I am running an MSD box with a Flamethrower II coil. The plug wires are Taylor 8mm silicone and are in good condition. All other plugs are burning just right so I think I will replace the #7 plug and install the new cap and rotor and see how it goes. Mike, sorry to hear that you have had similar issues with these aftermarket caps and rotors when exposed to hot spark, but it's good to know I'm not the only one.
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By miker - 7 Years Ago
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Dry lakes has a good eye, I missed that. I'm going to throw this out as an example of both corona and the cheaper caps.
I failed to fully seat the coil wire in the center of the cap. The car ran fine, but one night I had the hood up in the dark and could see a blue flicker at the center of the cap. I turned the lights on, shut it down, and pulled the coil wire. The Bakelite on the center was cut half way around, like with a small plasma cutter. The arcing inside that cap, and the created corona was eroding the Bakelite. Wouldn't have been long till it failed.
Drylakes, I never got over 15kv in our inside work, but even there it was dangerous.
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By Rono - 7 Years Ago
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Dry Lakes;
I don't think your crazy and I understand what you are saying, except maybe for modifying the rotor contact by bending it down and filing it flat. I will try the new rotor and cap, but if the rotor is not centered in the cap, I don't know what I can do about that. Manufacturing flaw and poor quality control I guess. I did think it was odd that the cap contacts were not burned on the vertical surface, but where the contacts met the plastic.
Rono
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By charliemccraney - 7 Years Ago
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That you have play without the rotor and none with the rotor must mean something. I don't see how simply putting the rotor in place would remove play.
Given Drylakes' observation of the rotor positioning relative to the cap, that also suggests something going on either directly or indirectly related to the rotor.
My thought is to make sure that the Pertronix magnet wheel is installed onto the points cam completely and correctly and to ensure that it is not contacting something that it should not.
Examine the magnet wheel for any manufacturing defects.
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By john2747 - 7 Years Ago
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Rono,
I have seen this problem before on a 59 y-block distributor.That 5/8 inch dia. sleeve that the rotor mounts on,ford calls it the cam assembly has a small horse shoe wire clip that holds the cam assembly from slipping off of the shaft.If that wire clip is bent out of shape when it is removed and then reinstalled without repairing it,it can allow the rotor to ride up and contact the distributor terminals.That horse shoe wire clip acts as a snap ring and fits into a grove in the distributor shaft.A worst problem would be the distributor main shaft has excessive end play and allows the rotor to run higher than it should.If you have a combination square that has a 1 inch wide x 12 inch scale lay it on edge on top of the distributor bowl [no cap] and check to see if the cam assembly can be pulled up more than 1 1/8 inches higher than the top of the bowl.Ideally it only needs to be 1 1/16 inch higher.Good luck.
john2747@telus.net
Prince George BC
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By 2721955meteor - 7 Years Ago
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i use the ford duraspark2 on my 57ranchero,original style cap and voter as well as stock coil.have 4years with no issues,drive aprox9months per year'after siting for3 months this winter started instantly . dont race but buz it up to 5000 .we live in surrey bc lots of moisture..the series 2 has a provision for5dgrs retard on start. i don't use that part. there was good info on this site.. i found a easy wiring scematic in a older manual,could email a copy if any 1 wants.. later distributors are very easy to convert.
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By DryLakesRacer - 7 Years Ago
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John2747 has it. I thought about it and this morning was going to suggest pulling up and down on the dist drive to see how much play it has. I did not know about the horseshoe rings he spoke about, very good knowledge to have and thank you. Bending the rotor tip is a bandaid at best the rotor is still to high but if everything else clears will help. Rono I know you will but carefully check every connection on #7 and make sure they are clean and also the porcelen on the plug for a crack. Good luck.
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By 57RancheroJim - 7 Years Ago
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Just another thought. Could the clearance between the bottom of the body and the collar on the lower part of the shaft be excessive causing the shaft to move up? My friend had this problem on a rebuilt distributor.
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By 2721955meteor - 7 Years Ago
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john is right re the wire clip,if it is not in the grove it will allow the rote and plate to rise and that alows the thrust plate to come out of place. only cure is get wire clip out remove the plate and be sure the thrust washer is in position,then you must put wire in place. a fiend of mine made a tool from a piece of tubing to inst the clip.. removing the clip usually looses them or damage them. you must reins the wire clip. a friend made a tool to position the clip,from a tubing piece., works well.
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By 55 GLASS TOP - 7 Years Ago
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Hello I am not the best guy with a wrench ,I am sure there are guys who know more than I but if the guy has a miss in only one cylinder #7 and he has good compression . Do you think it would be wise to ohm out the ignition wire and change the plug before he removes a dizzy because there is five thousands play. Like I said I do not know to much is there some reason why a minimum amount of play would only affect one cylinder.
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By Sandbird - 7 Years Ago
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Ron,
Did you try rotating the magnet ring to see if the miss moves to another cylinder? I have seen the magnets go bad on crank triggers and drive shaft sensors on race cars.
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By Rono - 7 Years Ago
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It seems like replacing the cap and rotor has cured the problem...for now.
Rono
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By Rono - 7 Years Ago
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Well, I lied. The problem still persists. After reading the post regarding ignition coil orientation (horizontal vs. vertical) I thought I would try replacing the (Flamethrower) coil as it is in the horizontal position and is about 8 years old. That made no difference either. As I said earlier in this post, I did notice a slight side-to-side play in the old distributor shaft, so this was my next option. I used my remote start button and brought the crank around to TDC. Leaving the plug wires attached to the cap I removed the cap and noted the rotor direction. The old distributor was a rebuilt Motorcraft with a Pertronix ignition and came out fairly easy. It had an "O" ring seal. The oil pump drive shaft is an ARP piece and stayed put in place. I bought a new Pertronix ignition and installed it in the replacement distributor which is a FoMoCo before trying to put it in the car. The replacement distributor uses a paper gasket instead of an "O" ring but otherwise, the two seem identical. My issue now is that I can't get the distributor to seat against the block. It's about 1/4" away, but in the correct position. I could possibly use my remote start to bump the ignitioin, but I'm afraid of loosing my TDC location. I know there is a trick to this, but I can't remember what it is. Any help would be appreciated.
Thanks,
Rono
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By miker - 7 Years Ago
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Rono, you're trying my memory way bad. When I had my first y block in the late 60's, I had that problem all the time. The gear engages, but the oil pump drive doesn't. I assumed it was the 30 weight oil in a cold motor, and when you pulled the dizzy, the oil pump went back due to suction. I'd just bump it with the remote button, and it would drop down on the next engagement on the hex shaft. My assumption was the gear engaged first, and then the shaft didn't line up. Been just under 50 years, and it doesn't seem to happen with multi vi oil and the gear drive pumps I have now. But that old car was a gearotor, or whatever they're called.
Hopefully someone else will chime in.
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By charliemccraney - 7 Years Ago
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As long as you are sure that the distributor is about where you want it, hold the distributor down slightly with your hand and bump the starter. It will fall right in place.
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By 55 GLASS TOP - 7 Years Ago
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Just curious you have miss on one cylinder. Have you checked the ohms on the wire have you changed the plug. I must be missing something everyone seems to think the dizzy is at fault. By no means am I the best mechanic but I always start with the basics.
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By Rono - 7 Years Ago
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Charlie;
Thanks for the tip! The dizzie went right in when I held it down and bumped the remote start. Glasstop, the plug wires are new, 8mm Taylor wires. I haven't checked resistance on #7 plug wire, but being that they are new I didn't think I needed to.
Rono
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By MoonShadow - 7 Years Ago
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Just swap at the cap and plug with the wire next to the suspect one. If the plug problem moves then its the wire.
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By 55 GLASS TOP - 7 Years Ago
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Just wondering if you ever found the source of your miss
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By Rono - 7 Years Ago
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Glass Top;
Yes I did. It was a worn distributor shaft bushing causing a slight wobble in the shaft and misfiring on #7 cylinder.. I installed a new (rebuilt) FoMoCo distributor with new Pertronix ignition and even bought one of those new style timing lights with the degree dial on the back to get everything timed correctly. The motor is running great again now.
I did notice there is a new small cap HEI distributor for Y Blocks being sold on Ebay from CRT Performance that includes the coil and pre-cut 8mm wires for $214. Here is the item number; 351894808762
I was wondering if anyone has tried one of these?
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By charliemccraney - 7 Years Ago
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Those are Chinese MSD imitations. I know people have used them. Buyer beware, though. Since they are Chinese, don't expect any kind of support if problems arise. Another thing to consider is tune-up part availability - the cap and rotor, when they need replacement within a few years, as all do with normal use, will they be available or do you have to buy another entire $220 distributor?.
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By Rono - 7 Years Ago
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Good advice Charlie. I did buy a new MSD distributor for my blown stroker motor, but the distributor that went bad in my 56 was a rebuilt unit from NAPA. It did go through several dyno pulls and I did make a pass on a race track in Maine with it, but it only had 7,000+ miles on it when the bushing failed. Our Ranch Wagon needs a distributor upgrade so I think I will go with an MSD unit when the time comes.
Rono
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By Rono - 7 Years Ago
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One small problem that has developed now is an erratic idle when the motor is hot. I am running dual Edlebrock 500 cfm carbs (#1404) and have set the initial advance at 12 degrees BTDC. The motor has a Comp cam with a .389 lift and I'm not sure if I need more advance or it's an A/F mixture issue. The manual on the Edlebrock carb says you need to adjust the fuel mixture screws with the motor hot and the air cleaner in place. I have a 1 piece air cleaner that mounts over both carbs and I can't get to the adjusting screws without removing the air cleaner. The manual does not give you a starting point for these mixture screws (i.e. 2 turns out from a lightly seated position) so I have no baseline to work with. Even if I increase the idle speed screw, it will still have an erratic idle. It did not do this prior to replacing the old distributor so I question that the fuel mixture adjustment screws are the answer. I have also checked all my vacuum lines and plugs and have retightened all carb studs so I don't believe I have any leaks there. Kind of stumped.
Rono
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By miker - 7 Years Ago
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Just a thought. If the vacumn advance is hooked up, either ported or manifold, is the advance in the new one about the same as the old one? I'm assuming the 12* initial is with it plugged off.
My older Edelbrock (I'm pretty sure) said to start at 1 1/2 turns out. No idea on a dual set up.
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By Rono - 7 Years Ago
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Mike;
Good thoughts. When I set the initial advance, I did disconnect the hose from the vacuum canister, but I didn't plug it off. I will re-check the initial timing with both the carb vacuum port and the vacuum canister plugged. I believe both distributors were similar, the old a Motorcraft and the new a rebuilt FoMoCo. Thanks for the info on the A/F mixture screws. I won't mess with them yet until I look more at the timing.
Thanks,
Rono
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By charliemccraney - 7 Years Ago
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Since ignition is what you have changed, ignition is the most likely cause. You cannot assume that a rebuilt distributor is going to be curved the same as your old one. You will need to check and adjust all aspects of it. If you do not know how the old one was tuned, and it may not be possible to find out, given it's problems, you will need to start the tuning process from scratch.
Regarding the mixture screws, the initial setting is not that important, so long as you know what it is and the engine will idle well enough to begin the tuning process. The initial setting is rarely what the engine actually needs. You just need to know where you started so you know where you ended up. I don't know what effect the air cleaner has.
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