Backfiring through the carb

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Model T Ford Forum: Forum 2015: Backfiring through the carb
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dena & Dennis Gorder on Thursday, April 02, 2015 - 10:32 pm:

My 26, with a distributor, is backfiring through the carb. I have a good spark to all the plugs. If I short the plugs to ground the #2 and #3 have no effect on the engine. I have a new carb and it is open about 1 turn. Adjusting the mixture to very rich reduces the backfiring but still does not effect the engine when I short those two plugs. I have put new plugs in with no help. So I assume it is either a valve problem or could it be head gasket? I have not removed the valve cover yet. Any suggestions would be appreciated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Zibell on Thursday, April 02, 2015 - 10:37 pm:

Check the valves on cylinders 2 and 3.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Plank - Three Way, TN on Thursday, April 02, 2015 - 10:53 pm:

Have you changed the cam or cam gear recently? Any other recent work?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dena & Dennis Gorder on Thursday, April 02, 2015 - 10:59 pm:

No other work has been done. Car has been sitting for about a year.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Thursday, April 02, 2015 - 11:02 pm:

Look for a cracked distributor cap.

Look at the engine wires in the dark when running, you may have spark jumping from one wire to the next or an arc in your coil box.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Thursday, April 02, 2015 - 11:10 pm:

Agree with John. The most likely cause is the intake valves in those cylinders are hanging up/not completely closing causing the backfiring out those valves and through the carb. I'm guessing almost closed because you don't mention it running really rough like those cylinders not firing at all. What kind of oil is in the engine? Something lighter and allowing it to run for a while might break them free. If not that the valve cover is your next step.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Thursday, April 02, 2015 - 11:14 pm:

John is right, sounds like a stuck intake valve. I've had several flathead motors do this after sitting. PK


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, April 02, 2015 - 11:16 pm:

Check your compression could just be sticky valves or some thing not letting the valve(s) shut all the way. After checking the compression and if you find low readings, pull the valve cover off and look at the valves and check that they are gaped correctly and closing. These are things to check before spending money and time pulling the head.
The only way it could backfire through the carb is if the timing is off or intake valves are sticking open.
You could have a carbon trail in the distributor cap that under some conditions is firing the wrong plug, check and clean the cap. Wipe out and dry the cap too. Growing up in the country our drive way had lots of standing water. My VW needed the cap dried out often. Lots of moisture in the air can do the same thing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andre Valkenaers on Friday, April 03, 2015 - 12:38 am:

Dena and Dennis,

Did you try to inter change the 2 and 3 plug wire on the distributor??

If 2 and 3 plug wires are inter changed your engine will back fire and shorting the 2 or 3 plug will have no effect on the running of your engine.

Easy to check before starting a valve job.

Good luck
Andre
Belgium


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dena & Dennis Gorder on Friday, April 03, 2015 - 08:39 am:

Andre, you were correct. I did have the 2 and 3 wires interchanged. Now it is just getting the timing and carb set.

THANK YOU!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, April 03, 2015 - 09:28 am:

Dennis: let me ask you one question. You say it's you car and I'm assuming no one else worked on it. Mentioning you'd messed with the cap & wires would have been a major clue to your problems resolution. So why not mention the work you did as the wires didn't move themselves ? Not finger pointing mind you it's just that without the full story, which we apparently now have, stuck valves wouldn't have come up and more importantly you might have been sent on a wild goose chase. I think when I see a post like this the first thing I'll ask is " what work have you done recently"?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn-Monroeville OH on Friday, April 03, 2015 - 09:35 am:

I've gotten to where I number every thing especially wires that I touch! My lame brain can't remember 20 minutes what I just did with something, and that's how things get messed up.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Friday, April 03, 2015 - 09:43 am:

Regardless of the path, I just love happy endings! :-O


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dena & Dennis Gorder on Friday, April 03, 2015 - 09:50 am:

I did add a new routing system for the wires but I thought i had them in the same location as before. I believe I assumed the distributor rotated in the opposite direction.Sorry Charlie that I left that info off, but I assumed I had it right.
Tim, good suggestion.
Thanks Mark, me too!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, April 03, 2015 - 10:09 am:

The post was not meant to mock you & if it's taken by you or any other Forum member I apologize for that. It's simply that (and this is my fault for not asking) the original post strongly suggested that the car sat for a year and when started up suddenly had 2 dead cylinders and was backfiring through the carb. I don't think any of us would have gone with valves if the information about working on the distributor had been included. I feel now that when answering a post like this the first query should be something like what work did you do and was it OK before you did it? I and others are trying to get you running not wasting your time and money by sending you every which way.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dena & Dennis Gorder on Friday, April 03, 2015 - 10:22 am:

I did not take it as mocking, however, some people could have. It is always hard to tell how a message or email is meant. We need to be careful how tings are worded so we do not chase people away. My mistake is that I thought I had them connected correctly and was pretty sure of it. I even bet at least one time in your life you were certain you were right, but weren't.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Friday, April 03, 2015 - 10:27 am:

That is a common problem, if you switch from a distributor that turns clockwise to one that turns counter-clockwise or vice-versa.

Many of the older distributors turned clockwise and used a toggle to correct the advancement curve.

The newer distributors turn counter-clockwise and have eliminated the extra toggle part.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, April 03, 2015 - 11:56 am:

Are there aftermarket T distributors that turn in opposite directions? I guess if you engage the drive gear from the top or bottom would make a rotational difference wouldn't it? Just curious.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andre Valkenaers on Saturday, April 04, 2015 - 02:23 am:

I apologize for having found the problem yesterday morning but I must be honest, I was there two years ago.
This said, I don't like a distributor or electronic ignition on the Model T. I find a T engine come really to live with a right working original four coils ignition. I like the ticker noise while I am running my T's. It make me thinking of the heart beat of my love when we ... .

About trouble shooting: After 40 years of working as a mechanic on Ford cars an tractors I learned this. Just go back to basics and start with the easy controls first. Do not directly put in the computer, just look at the engine and look for a loose wire, a missing bolt, an gasket that comes out its setting, ... The easy stuff first.

Happy Easter
Andre
Belgium


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