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Intermittent carburetor backfiring on both sides

Tiny
STEVE W.
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Backfires are commonly from timing issues not from the carburetor. As for the cooling problem, a good 4 core radiator and the OE mechanical fan and shroud will do the job as long as the system is clean, you might need a small electric if you set in stop and go traffic but the stock system shouldn't have an issue. I would say you had a cascade of issues that all triggered at once. As for the repairs I would get the carburetor on the engine, Then take a look at the ignition system to be sure it's in time. It also sounds like you are running the OE alternator which is not able to cope with the heavier load, that is common as the older cars ran very small electrical systems compared to modern cars. You can get alternators that will put out more current and can keep up, but first let's get the engine running.
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Wednesday, May 12th, 2021 AT 6:18 AM
Tiny
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I know you have a lot to read but you're not reading it correctly causing you to have to revisit and worse me having to retype it. I do it myself sometimes.
It's easy to guess and most of the time we're okay. However; what I said was that I didn't have the original 37 amp alternator that I had replaced it (with a 100 amp). My point was I could reply to all their BS because I knew what I had done and when I did it and I knew it wasn't dieseling in cold weather and when it came back it did that everytime the car was shut off.

Just so we're clear I get backfiring out of either side every minute or so which is a newer problem that followed the dieseling which ended in explosion because the only way I could stop the dieseling was to flood it out and that ended in an underhood explosion smoke pouring out the hood and all. That's why I brought up about the dieseling fixes as it would have carried on for quite some time. I think its better to have something in place and not need it than to resort to flooding it.

The car worked fine when I dropped it off the first time. It wasn't overheating in the cold. I flushed the radiator twice and I cleaned out the gas as my supplier of non-ethanol had changed suppliers and I suspected a tank of bad gas as well. Then I found the short on the relay to the pusher fan which allowed the car to run without dying at each light or stop sign. And then the reversed fans and that was were I stopped in winter.

That wire that he chopped I wonder if maybe that was a switched 12 going to the pertronix and the carburetor choke?
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Wednesday, May 12th, 2021 AT 2:17 PM
Tiny
STEVE W.
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Okay, missed the 100 amp. Your description sounds like one of two things, running hot would cause both of those issues, but how it's getting hot could be timing related, if it's running and advancing too far it will run hotter, and if the carburetor is running lean in the normal driving range it will get hot. Add in even a small amount of blockage in cooling and you get to where you were. As for the wire, if it was for the choke it would have held the choke closed as the electric opens it as it warms up. I would get it to at least start. Then check what the timing is doing, it's rare but the pertronix unit could be causing an issue.

Have you pulled the plugs out yet? If not, pull them and post a close up of each plug. Even after setting they should show if it was running hot and lean.
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Wednesday, May 12th, 2021 AT 5:36 PM
Tiny
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Back to the carburetor. I'm being instructed to install the accelerator check-valve pin into the secondary. I don't see any place to drop it on the secondary which has no metering block but a plate which may have nothing to do. I only have 1 pin which I'm guessing should go to the primary?

No, I don't have the plugs out yet. I need to get my neighbor to help me replace the hood springs. I've been relying on a piece of wood. I have the springs I just need to get them in and I don't have the strength.
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Wednesday, May 12th, 2021 AT 9:49 PM
Tiny
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My understanding of the Pertonix is it either works or it shuts off unless it's wired incorrectly - well before someone goes under your dash and all's working and then all's not working what are you going to do?
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Wednesday, May 12th, 2021 AT 9:52 PM
Tiny
STEVE W.
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The pin goes in the primary side unless you have a double pumper style carb that has dual accelerator pumps. With vacuum secondary's that is almost impossible.
That is how they are supposed to work, but if an internal part in the electronics fails all bets are off. It's one of the reasons why I normally go with a custom curve HEI unit. Drop it in place, add a switched power and wire it up. One thing to check on a 69 would be the switched power. Most points cars had a dual circuit for the ignition coil. When the key is in the start position the coil and points got full battery power to help with the voltage drop from the starter. Then once the engine was running and the ley dropped back to the run position the power went through a length of resistance wire to the coil and that dropped the voltage back to about 6 volts so the points lasted longer. If that wire is still in place or someone reconnected it you could have some interesting issues from low voltage to the system. I would think it was removed but I'm not the one who did the work on it.
You mentioned PA, ever watch Pine Hollow auto on you tube? Ivan is a real sharp mechanic who likes a challenge. Not sure if he would be interested in taking on a vintage car though.
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Wednesday, May 12th, 2021 AT 10:23 PM
Tiny
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So in my rebuild kit I got 2 gaskets for meter blocks and one that matched the shape of the secondary plate. I used the one shaped like the plate not understanding why you would use a gasket that wouldn't be properly pressed against the throttle body. The plate comes with those odd screws. Then when I was looking for something else I saw them attach their plate to a full gasket. What the heck is the plate sized gasket for if not for putting between the plate? If I had a full-sized metering block I'd have used the full size gasket. Am I right on this?
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Friday, May 14th, 2021 AT 1:51 AM
Tiny
STEVE W.
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There should be a plate gasket, but on some carburetors that gasket is part of the full sized gasket used to seal the bowl and others it's a different piece. The kits usually include a few different parts to match what your particular carburetor uses. Plus there are some updates they did through the years so they include those parts as well.
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Friday, May 14th, 2021 AT 6:17 AM
Tiny
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Just to verify you are saying that you think I choose the correct gasket for use on the secondary plate?

I got the electric choke on but I'm not sure if there's a linkage issue or something. I can't seem to move it at all unless I first open the throttle.

The red cam also shows a silver ball in the end (perhaps used for weight?) Mine has a hole but no metal ball. The metal triangle that holds the spring on is broke I think it's copper so I guess I could solder it.

My instructions told me to put the choke together but as I recall I have to do the secondary accelerator because there's a screw that goes under the choke that you can't get at once it's done.
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Friday, May 14th, 2021 AT 9:50 PM
Tiny
STEVE W.
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The choke is correct in needing the throttle to release it. That is why you need to step on the gas at least once in a carbureted vehicle, that "sets the choke" by releasing it so it can close on a cold start. Then once it warms up the electric, manifold or exhaust heated pull off system holds it open. Some carburetors also have a vacuum choke pull off that will modulate the choke using vacuum passing through a temperature valve on the thermostat housing. You also will adjust that once you have it installed. The linkage bar can be bent to close it tighter but it shouldn't be needed, you don't really want the choke to seal the inlet off because it does need some air to go past it to atomize the fuel and in the event the choke were to stick you could still move the car around. Once you get it installed you will adjust the cover to keep the choke on for the correct amount of time based on the way the engine warms up and the climate you have. Colder area likes the choke to stay on longer as a general rule.

The gasket depends on what it had originally. Some used a gasket for the metering block and bowl as one piece, some used a similar gasket with the metering plate, Others used two gaskets for the plate, one for the plate and another for the bowl, as long as the holes all line up and it seals either one should work.

The broken part sounds like the choke cap retainer, looks like the picture? If yes you can get them as replacement parts. They simply push the cover in solid to keep crud out of the housing.

Video was a good idea.
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Saturday, May 15th, 2021 AT 9:54 AM
Tiny
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It's not copper. It that metal they use to frame out consumer electronics it may not solder. It is the retainer for the choke spring housing.
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Saturday, May 15th, 2021 AT 12:21 PM
Tiny
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The ball in the fast idle cam? https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F292973652408
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Saturday, May 15th, 2021 AT 12:31 PM
Tiny
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I'm trying to do the vacuum secondary. First which hole does the ball go into? The top or the bottom top or side? Should I put Vaseline on the edges of the diaphragm to help seal it?
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Saturday, May 15th, 2021 AT 1:30 PM
Tiny
STEVE W.
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That retainer is the fancy version of the one I posted Holley used both as well as a wire version. It's actually just cad plated steel but I would say replace it, they are cheap.
That spring isn't really a spring, it's a bi-metal strip that heats up and pulls the choke open as it heats. The terminals on the outside go to a good ground and a switched power.

The ball is there to pull it down, if yours is missing replace the cam with the correct one for the application.

The check ball goes in the lower section of the secondary diaphragm housing, then the diaphragm and spring then the cover.
No on the vaseline it should seal on its own.
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Saturday, May 15th, 2021 AT 3:24 PM
Tiny
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I presume you're telling me to drop the ball in the top of the bottom, not into the side of the bottom?
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Saturday, May 15th, 2021 AT 3:34 PM
Tiny
STEVE W.
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The ball goes inside the housing in the vacuum port that attaches to the carb body. There will be a gasket, then the passage goes into the secondary housing and makes a right turn and comes up through the diaphragm and into the top cover. The ball goes in the upturned section right under the diaphragm. The check ball passage will have a round hole with a notch in one side. The idea of the ball is that it slows the rate that the secondary's can open. It's one of the trial and error parts in that carb. Some engines need it and some don't. If the engine needs it you will know because the engine will bog as the fuel flow won't keep up with the increase in air through them and you get a big flat spot and lean mix. The ones that don't need it will run just fine. Most of the OE Holley carbs that came on GM engines don't have it.
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Saturday, May 15th, 2021 AT 4:25 PM
Tiny
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This connection between the throttle and the secondary plates doesn't do anything at all. I wouldn't think this is just for looks.
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Saturday, May 15th, 2021 AT 4:35 PM
Tiny
STEVE W.
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It will when the carburetor is actually working and creating vacuum and the choke is on.
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Saturday, May 15th, 2021 AT 5:17 PM
Tiny
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This is the 3rd time I've written this. Which way does the secondary plate attach? Like in the video or flipped around so like 180 degrees. It connects either way.
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Saturday, May 15th, 2021 AT 7:21 PM
Tiny
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Can't find what Holley calls a therm housing clamp on any website except in a complete electric choke setup kit for $70.00.
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Saturday, May 15th, 2021 AT 7:25 PM

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