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Old 11-21-2020, 09:01 PM   #21
cousinjd
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Default Re: Miss on newly rebuilt 292

I know it is a PIA but you might try pulling plug wires at the plug instead of the dis cap. That way you know the spark is getting to the plug. Just a thought. Jim
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Old 11-21-2020, 09:02 PM   #22
cousinjd
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Default Re: Miss on newly rebuilt 292

You might try pulling the plug wires at the plug to make sure you are getting spark at the plug. Just a thought Jim
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Old 11-21-2020, 09:12 PM   #23
Daves55Sedan
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Default Re: Miss on newly rebuilt 292

If the miss is not erratic, but rather, symmetrical or occuring at the same cylinder each revolution, the first suspect would be the plug or plug wire for that cylinder. If you can identify which cylinder is miss-firing, it's usually a matter of just replacing the ignition parts for that cylinder (at least in your case whereby compression and so forth seems to be okay).
Check underside of distributor cap to see if a portion of the tower socket on one of the cylinders has a gorge in it or is busted off altogether. That could be your problem.
Another thing to check is the distributor cap tower sockets at the top. Pull the plug wires out of each one-at-a-time and see if any tower sockets are greenish looking. If so that is corrosion which is preventing electrical continuity between the tower socket and plug wire terminal. This is something you always need to keep in the back of your mind for misfire problems if you live in an area that has morning dew and condensation during the transition between late afternoons and evenings (usually in spring and fall seasons).
If this occurs, you can clean that tower socket with a chemical or spin a piece of crocus cloth around in there with the butt end of a pencil until it is shiny copper or aluminum, whichever version of cap you have. THEN, you need to get a pipe cleaner, treated with high-dielectric silicon compound and smear it all around in EACH tower socket, then plug your wires back in. Make sure all the rubber boots have NO cracks and are still pliable or replace them.
What I would say you could immediately ignore is points and condenser. If the points are carrying the spark for other cylinders, it wouldn't skip just that particular cylinder every time.
For the most part, condensers either work for all cylinders or they don't work at all. One notable exception is that the cheap chinese made condensers will break down at the point of an engine running at normal operating temperature, say 190 degrees, but the engine will keep running till you shut it off. If you come back and try to start the engine a minute later, it will never start until the temperature of the condenser decreases to around 95 degrees. Then it will start, but you'll have the same problem if you stop somewhere for a few minutes and want to start again.
All the chinese made points and condensers are very poor quality.
I have been using Napa Echlin brand heavy duty series without any problems the past couple years, but I think they're made in Mexico now. Not sure if the new ones are substandard as the chinese made junk is.
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Old 11-21-2020, 09:29 PM   #24
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Default Re: Miss on newly rebuilt 292

BTW, if you do have the dew and condensation problem in the area you are living in, you also need to keep an eye on the ignition rotor TIP (the portion that makes contact with the underside of the distributor towers). That tip will turn black and green causing poor electrical continuity between tip and tower.
You can carefully file the corrosion off the tip but don't take off too much metal. Just get it clean and shiny again. In the past, I have dunked my tip in a plastic jar full of acid and electroplated the tip using a small section of old copper tubing to help prevent the bare steel of the tip from corroding again too quickly. Never submerge the whole rotor in acid. Only hold the TIP of the rotor down into the acid so that the acid won't eat away at the connections between the metal tip and the spring-steel electrode for the coil tower. If there is no protection afforded to the bare steel tip, it will corrode VERY quickly and you'll be cleaning it again and again. It will be necessary to constantly move the rotor around in the jar as bubbles will form around the tip and you can't see if your tip is actually dipped in the solution. Try to get your piece of copper BELOW the rotor tip as that is all you are interested in plating, BUT DO NOT allow the copper tubing to ever touch the rotor tip.
After electroplating the tip, it is important to take another clean jar full of hot water and dump some baking soda in it, stir and wash the rotor tip in the solution with a terry cloth and dry the rotor. You can polish up that newly plated tip by sprinkling a little bit of rubbing compound on a shop towel and rubbing the tip back and forth upon the towel laying on a flat surface. That should help to keep the tip clean for a while, maybe a year.
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Old 11-21-2020, 11:45 PM   #25
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Default Re: Miss on newly rebuilt 292

The cap and rotor are new and look new. First thing I did was pull the cap and look for anything that was not right. The contacts are all clean and nothing looks out of place. There are no cracks or anything else. The rotor is the correct height and length (compared to the old one) and it is also new, clean and fully seated on the distributor shaft. Obviously something is wrong, I just haven't found it yet.

There is no corrosion on anything and the car has been is a dry barn during and since restoration and never stays outside.

The miss is not regular, it is erratic, at least at idle. Can't really tell at speed, just much more noticeable.

When the plugs are clean, it fires up immediately - like touch the key and it's running.
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Old 11-22-2020, 12:25 PM   #26
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Default Re: Miss on newly rebuilt 292

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On engines that set up for a long time or newly overhauled with tight clearances, a person can have fits finding out what all the little inconsistencies are. You could have a valve that is just a little sticky. It may not even show up on a compression test. It will likely show up on a manifold vacuum check if that is what is causing the intermittent miss.

Your plan to renew some of the ignition components is a good place to start. Easiest things first when troubleshooting.
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Old 11-22-2020, 06:53 PM   #27
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Default Re: Miss on newly rebuilt 292

For erratic misfires, check the following:
Carburator choke operation, choke butterfly should open as engine warms up.
Carburator idle/fuel mixture setting. With engine running and a vacuum guage connected to manifold vacuum, turn idle-mixture screws to get both the highest vacuum reading and smoothest engine idle. Start with screws turned all the way in and back out 1-1/2 revolutions. Vacuum reading should be around 19-20 and NOT erratic.
Carburator float setting. If float is stuck such the level of fuel in the chamber is too low to fire all the plugs, you may need to re-adjust float setting, but first, test fuel pump output. If fuel pump cant pump enough gas to the carb, fix or replace pump and leave carb float alone.
Vacuum. Check all hoses for cracks and fittings for looseness. Try to utilize as much metal tubing in the system as possible rather than replacing with rubber hoses. The old Fomoco products used as much metal tubing as possible in their vacuum systems. Good idea. It would be a good idea to replace old dried out vacuum hoses for the accessories like windshield wipers, heater temperature control system and windshield washer if so equipped. Make sure no original hoses are missing from the accessories.
An easy way to find out if you may be losing vacuum from the accessory circuit is to disconnect and plug the metal tubing leading into the firewall. Doing this will isolate the accessories system from the engine vacuum altogether. Then, get your engine vacuum straightened out first. After you are satisfied with that, go back and re-connect you main accessory vacuum hose and re-check vacuum results. If you now have low or erratic vacuum, something is amiss in your accessory system, right? !
Valve operation. Sticking valves may be causing the problem. Pop the rocker arm covers off and closely watch each valve make it's full travel with engine idling. Note: might be a good idea to rip off long pieces of aluminum foil from the little lady's kitchen so you can use them to cover over the exhaust headers as oil will squirt out of the rocker arm tops.
If any valves look like they are hanging up, you may have a bent valve or bad valve guide. Time for head rebuilding at which time you can redo valve seats too, grind valves and lap valves into seats, check for broken or weak valve springs. If a valve spring is weak, you can use proper size and thickness of washers to beef up the spring tension to specs.
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Old 11-22-2020, 07:45 PM   #28
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Default Re: Miss on newly rebuilt 292

Carb is new and choke disengages completely after warmup.

As I have already mentioned I adjusted the carb and have 19.5" of vacuum, the needle does move a little but adjusting the carb does not stop that - it has to do with the miss. As I also mentioned I have had the heads off during the rebuild, cleaned everything, lapped the valves, checked the guides and installed new seals, springs and retainers. All valves moved smoothly through the guides. I have also had the engine running with the valve covers off and they all move just like they should.

This is a 1959, there is only one vacuum system - the wiper motor and I have plugged that line while trying to get this running right. There is also the ported vacuum advance line from the carb, which is new and as has been tested and the advance is working correctly.
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Old 11-23-2020, 10:47 PM   #29
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I got some Mexican made Blue Streak ignition parts and installed them today. New coil, points and condenser. I also installed a new set of hotter plugs (Autolite 46 - Made in China).

I replaced the coil to points wire, the old one looked ok, no cracks or breaks in the insulation and tested good but its 61 years old. It looked like it was something like 22 gauge and I put in 18 gauge.

I also reinstalled the original rotor. I compared it to the new Standard Motor rotor and it was slightly longer. Maybe 1/16", don't know if that matters but I put the old longer one in.

It fired right up. It runs better but still has a slight miss. At normal temp I can idle it at spec of 450 rpm in gear. In gear running at 450 RPM there IS NO MISS but put it in park, the idle goes up to about 550 and the slight miss comes back in. The miss gets worse with higher engine speeds. BUT - much better than before.

I may try swapping out plug wires tomorrow.
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Old 11-24-2020, 08:13 PM   #30
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Default Re: Miss on newly rebuilt 292

You mentioned you're running an import carb right now. Is there any chance you have manifold vac at the dist. instead of venturi vac? If so it maybe advancing too much at low speed creating a miss fire. Unhook and plug the vac line to the dist and drive it to see if your miss goes away. Also, don't remember if this was mentioned, but is the bare ground wire on the breaker plate intact?
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Old 11-25-2020, 12:26 AM   #31
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Default Re: Miss on newly rebuilt 292

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. . . Also, don't remember if this was mentioned, but is the bare ground wire on the breaker plate intact?
Without a good ground wire for the points the ignition can't work correctly. photo # 1

With a Dwell meter you can use it to see how stable the Point gap is (or isn't). If the reading varies by 5 degrees or more the distributor shaft bushings are worn, which can cause inconsistent spark timing.
Back in post #1 you said, "Point dwell is at 28 at an idle but drops a little (22-24).." this could be part of the problem.
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Old 11-25-2020, 07:37 AM   #32
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Post Re: Miss on newly rebuilt 292

Quote:
Back in post #1 you said, "Point dwell is at 28 at an idle but drops a little (22-24).." this could be part of the problem.
This is normal with a 2pc advance plate.

Now the plates may be binding if a 2pc assembly.
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Old 11-25-2020, 12:50 PM   #33
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Default Re: Miss on newly rebuilt 292

I am currently running the import carb but the vacuum port seems correct. Checking timing - at idle vacuum line plugged set at 8 degrees BTDC. Increase engine speed and the mechanical advance works smoothly and increases timing to about 22 degrees.

Plug the vacuum line back in. Timing at idle is still 8 degrees, increasing engine speed advances the timing smoothly up to about 30-35 degrees total. It could be a little more as I only have marks for 0, 10 and 20.

The bare ground wire in the distributor is intact and firmly connected on both ends. I checked it to see if I should replace it and decide to leave it - looks good.

As far as the dwell changing... With the second set of new ignition parts (blue streak points, condenser, coil and Autolite 46 plugs) the dwell is at 28 and only moves 2-3 degrees to 25-26 with increased engine speed. The factory manual says 3 degrees is ok. I'm guessing the import points spring may not have been strong enough and might have been floating some. The blue streak points seem much better - copper body, stronger spring, larger point surface, etc.

I had cleaned and rebuilt the original carb but when I tried it I could not get it to idle - then bought the Chinese one. I pull the original apart again yesterday and I did find one problem. It looks like there were 2 gaskets stuck together on the power valve and I did not notice it. May have changed the position enough to cause an internal leak. I've fixed that and will try it again - maybe over the weekend.
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Old 11-27-2020, 05:11 PM   #34
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Default Re: Miss on newly rebuilt 292

Be careful not to loosen the nut closest to the points flat spring. If that spring tension is too loose, the points will flutter at higher RPMs and cause misfiring. If that spring tension is too tight, the rubbing block on the points will wear down against the distributor cam causing the point gap to become more and more closed. The outer nut is the only one you should need to remove for installing wires.
Having two gaskets on the power valve should be okay as long as the gaskets aren't so thick that the assembled main body doesn't end up standing off the valve body due to the power valve being too far out and hitting the power valve recess in the valve body.
If the bottom surface of the main body where the power valve gasket surface is has defects or is scored, it can be milled down flat, then you could use one gasket, maybe even one of the nylon gaskets they give you in the carb rebuild kits. But sounds like your original carb has more problems than just that.
If worst-come-to-worst, you can always send your original carb to Sal Cicala, and he will fix it up for you.
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Old 12-05-2020, 07:18 PM   #35
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Default Re: Miss on newly rebuilt 292

Deleted some posts and temp banned some users... please remember that we have a zero tolerance policy on politics.

Thanks fellas.
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Old 12-07-2020, 05:56 PM   #36
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please remember that we have a zero tolerance policy on politics.

Bless you. Places without politics feel like a real haven these days.

Last edited by NoahVail; 12-08-2020 at 10:32 AM.
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