I have a recently rebuilt 2056 dual carb motor running electronic distributor that McMark built in 2019. Car has been running flawlessly until now. I go to drive it today and it's absolutely sluggish. Not revving or pulling as it should. I thought okay I'll try to pull the plug wires off off the distributor one by one with pliers while idling to see if it changes so I know what cylinder is dead. I could pull both driver side plugs off with no change. As soon went to put back on there was spark at the wire and cap. When I pulled the passenger bank off then driving died. Thought odd maybe fuel issue on the driver's side bank but can see fuel squirting into the carb.

So this is why I think both driver side cylinders are dead. Any thoughts on what it could be or where to start?

I'm not sure why you would be rebuilding an engine that was just built 3 years ago, by a reputable builder, but I will offer some advice all the same.

Edit: Also make sure the wires are correctly placed. I know it is easier to forget 1,4,3,2 and put the plug wires in the wrong spots which would make it not fire except on those 2 cylinders. Like if you swapped 1 and 2 you would be firing 2 when 1 is supposed to fire, so it appears dead, then 4 fires as it should, then 3 then 1 is firing when 2 is supposed, so dead. That little mix up would make the driver side dead, but the passenger fine.

First and foremost make sure your timing is correct. Go with a static timing of TDC so at least you know you should be firing all the cylinders correctly. This means making sure the distro angle is at the correct spot on cyl 1 plug wire AND cyl 1 is at the top of the chamber AND the fan shows the mark for 0/TDC. I'm going to assume you did not buy all new ignition parts. So your plug wires could be faulty, try to swap them around to see if it follows the wire. Next, you need to check the distro is still functional. You didn't mention which one so it could be 3, Mallory, Pertronix, 1,2,3 ignition. If it is a 1,2,3 make sure you set it correctly following the instructions. I have not heard of one going bad. For the Mallory I'm not sure I don't have a lot of experience with it. For the Pertronix they do go bad, but is rare. I did however buy one new and it had a dead cylinder. Support said there is no way that only one cylinder would be bad. I did the same test as you and cylinder 4 would not fire. I sent it to them and sure enough it was faulty. 2 on the same side leads me to believe it is a timing issue. Lastly, if you have a 009 or other points distro, try throwing that in and using that to rule out the electronic distro.

Sorry if I wasn't clear. I am not rebuilding the engine now, it was rebuilt by McMark 3 years ago after the car seat for almost 20 years. It got all new plugs and wires during the rebuild. Regarding the dizzy, I'm actually not sure the brand as that wasn't new during the rebuild. It does have a new Fast XR700 box on it.

I can check the timing as that's easy enough but I just can't see that being the issue . When I put the car away last it ran perfect, it sat in the garage for about 2 weeks untouched, hop in it and now and it runs like crap so I don't see how the timing could change.

I know the wires are in the correct spot but good idea about switching them to see if a wire is bad. I'll start there and report back.

Troubleshooting 101:

Don't assume it's ignition & Don't assume it's carbs. Each is easily mistaken for the other.

Dirty / contaminated idle jets will do exactly as you've described. So will bad ignition.

Will the 2 bad cylinders run if you hit them with starting fluid? Do they light off?

I also don't see any indication that you've pulled the plugs and verified they are fouled and/or that they are actually sparking at the plug.


Bottom line - you have to isolate whether its a fuel issue or ignition. Just because you can see fuel being squirted by the accelerator pump don't assume that the idle circuits are working.

So got around to looking at the car this weekend luckily the fix was simple. After having to do some repairs on the driver side carb base (that's another story for another time) I went to look at the passenger side base for reference and found the throttle linkage was missing. It was lying on the tins. Somehow feel off . After I reattached car runs great again. Phew!

You need new air filters.

Ha ha. That was going to be my first guess. Why? Because I'm a serial offender. I've lost count of the number of times I've forgotten to tighten the linkage nuts after balancing carbs or worse, left one side completely disconnected.

Noticed you have the tin hole open for the heat J tube. Try to cover that to lessen warm air coming from the bottom that will make your oil temperature hot.

Why. They are very new. Maybe 1k miles on them if that.

Yeah I'm not running any heat stuff in the car as it only gets driven on very nice days. Will look into blocking those off. Thanks for the tip.

check with bdstone for the round cover kit for those holes and for the front fresh air vent hole

Noticed you have the tin hole open for the heat J tube. Try to cover that to lessen warm air coming from the bottom that will make your oil temperature hot.
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Yeah I'm not running any heat stuff in the car as it only gets driven on very nice days. Will look into blocking those off. Thanks for the tip.
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check with bdstone for the round cover kit for those holes and for the front fresh air vent hole
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@R Dub

I have sets of blockoff plates for the J tube holes.

Ah will do. Thanks!!

[quote name='bdstone914' date='Jun 11 2022, 06:16 PM' post='3008022']
Noticed you have the tin hole open for the heat J tube. Try to cover that to lessen warm air coming from the bottom that will make your oil temperature hot.
[/quote]

Yeah I'm not running any heat stuff in the car as it only gets driven on very nice days. Will look into blocking those off. Thanks for the tip.
[/quote]

check with bdstone for the round cover kit for those holes and for the front fresh air vent hole
[/quote]
@R Dub

I have sets of blockoff plates for the J tube holes.
[/quote]

Awesome just PM you about those

that is fast!