Backfire thru the Carb

[Tom Wesenberg]

Have you pulled the top distributor plate and looked at the connecting wire? It could be loose or intermittently grounding to the case when you move the spark lever.

An intermittent distributor connection can cause a misfire which allows unspent fuel to accumulate in cylinders. That extra fuel could cause a backfire.[/QUOTE

I don't have the pigtail on this car. I have the conversion upper plate. .

That's been the root of many problems.

 

[Mitch//pa]

backfiring through the carb or popping with the timing retarded can be attributed to a lean mixture. open the GAV some and see if that helps any. of course also make sure your base settings are all correct, points, timing etc. i also have had those wireless lower plates, bad lower plate wire, bad condenser cause that also. there may not be a single answer for this so take it one step at a time

maybe ill quote myself also

 

[Tom Foster]

Tom, why don't you load it up and trailer it down so we can look at it together. .....oh wait, your trailer is already at my place!! . . [/QUOTE]

So that's where my trailer is! Last I looked it was next door in the vacant lot...about five minutes ago.

I love it -- we finally managed to get Brent confuzed. Wrong Tom, Brent!

My "Something else" comment was meant to convey that "backfires" are usually not true carb backfires but exhaust explosions that can have many causes but are easily confused. "BANG! Oh! the car backfired"... not really.
Fearless

 

[BRENT in 10-uh-C]

Tom, why don't you load it up and trailer it down so we can look at it together. .....oh wait, your trailer is already at my place!! . .

So that's where my trailer is! Last I looked it was next door in the vacant lot...about five minutes ago.

I love it -- we finally managed to get Brent confuzed. Wrong Tom, Brent!

My "Something else" comment was meant to convey that "backfires" are usually not true carb backfires but exhaust explosions that can have many causes but are easily confused. "BANG! Oh! the car backfired"... not really.
Fearless[/QUOTE]


Yes Tom Foster, it would seem that way but I was typing on my iPad and so I did not quote Tom Witten's post. Yes, Tom Witten's trailer is parked at my shop, ....and I am NOT confused about that.

.
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Now what is even funnier (-at least to me) is to sit on the sidelines and observe the comments/suggestions that are randomly thrown out here. My luxury in this is that I know Tom's car(s) pretty well, and have a good idea of what is/isn't the likely culprit based on how often the car is driven/etc. When I compare the advice offered to others by knowledgable folks here, I cannot help but wonder how the typical novice Model-A mechanic does not get bogged down to the point of being in worse shape after they have tried the suggested checks & repairs. This is NOT showing criticism to anyone but to point out that we as posters have the potential to do as much harm as good to those in desperation seeking to solve a specific issue on their Model-A.

 

[newshirt]

Now what is even funnier (-at least to me) is to sit on the sidelines and observe the comments/suggestions that are randomly thrown out here. My luxury in this is that I know Tom's car(s) pretty well, and have a good idea of what is/isn't the likely culprit based on how often the car is driven/etc. When I compare the advice offered to others by knowledgable folks here, I cannot help but wonder how the typical novice Model-A mechanic does not get bogged down to the point of being in worse shape after they have tried the suggested checks & repairs. This is NOT showing criticism to anyone but to point out that we as posters have the potential to do as much harm as good to those in desperation seeking to solve a specific issue on their Model-A.

Gosh, it's a little hard to troubleshoot an issue with only a few lines of description and no follow-up. That's completely different than seeing the car in person. So, forum help carries with it some risk that responders won't fully comprehend the issues without good information and timely responses. It seems like everybody tried their best with the information they had.

 

[Mitch//pa]

yep and the suggestions are not even read. OP states that it has an wireless plate.. that has been mentioned as a possible problem area yet it keeps getting brought TTT for more suggestions and no real dialouge.. Brent since you built this car i am suprised it has the wireless plate
yes it frustrating for all of us..

 

[BRENT in 10-uh-C]

yep and the suggestions are not even read. OP states that it has an wireless plate.. that has been mentioned as a possible problem area yet it keeps getting brought TTT for more suggestions and no real dialouge.. Brent since you built this car i am suprised it has the wireless plate
yes it frustrating for all of us..

Mitch, I didn't do this car. Tom purchased it off of eBay about a decade ago. It had the plate on it since the restoration.

 

[Mitch//pa]

oh i take back that last statement i shouldnt have assumed....
for some reason i thought you restored it maybe i am confused..

 

[Mitch//pa]

i feel Tom was given enough basic info that he can try especially just turning the GAV knob first....were sort of left in limbo to know if that was tried yet....
its really hard doing this over the internet and harder without return dialouge

 

[BRENT in 10-uh-C]

...were sort of left in limbo to know if that was tried yet....its really hard doing this over the internet and harder without return dialouge

Again, this yet another situation where not all the facts are known first. The entire State of Tennessee is under a state of Emergency, and Tom's area in S/W Virginia is also under a similar watch with an inch of ice covered by a foot of snow. Snow plows and emergency vehicles are struggling to even get to his area (-by his posts on Facebook) so he really has not had the ability to get the car out even if he wanted to.

I sent you and several others a PM awhile ago but this addresses a concern that I and several others have expressed as a fault with Fordbarn. So often, people here are so excited to help they often do NOT take the time to read the post and the subsequent suggestions. Then it seemingly becomes a contest to see who can post up a theory just for the sake of doing so whether it is relevant or not.

 

[newshirt]

So often, people here are so excited to help they often do NOT take the time to read the post and the subsequent suggestions.

Sure, I was one of those people.

I can't explain what happened in this case... but I'm certain I took the time to read every post. I didn't race. I typed out a thoughtful answer. It just happened to be a repeat of what was already suggested. I don't know why I missed those previous suggestions and then repeated them. Brain fog? Gosh, it happens... I've seen it dozens of times on FB and other places.

The point is, we are human and make mistakes. Yes, we take the time. But we still make mistakes.

 

[tbirdtbird]

I think the regulars are being squeezed here yet they all gave good solid advice.
I am pretty sure we have done way more good than 'harm'. There is often positive feedback publicly here and many of us get tons of PMs loaded with thanks.

A comment I will make is that in general, the reading comprehension of the viewers and many posters and users with questions is quite low. The same advice gets posted 3 times in a row by different members. Posts are forever being misread. Like the guy with a bent valve. One dude didn't get that simple statement and gave poor advice as a result.

I think if I had a good friend one or two states away with a problem that I would be on the phone with him in a heartbeat once I learned he was having trouble.

Bottom line here, don't throw the baby out with the bath water!

Now, back to the shop so I can grease up my piston rings

 

[BRENT in 10-uh-C]

Sure, I was one of those people.

I can't explain what happened in this case... but I'm certain I took the time to read every post. I didn't race. I typed out a thoughtful answer. It just happened to be a repeat of what was already suggested. I don't know why I missed those previous suggestions and then repeated them. Brain fog? Gosh, it happens... I've seen it dozens of times on FB and other places.

The point is, we are human and make mistakes. Yes, we take the time. But we still make mistakes.

Ray, I am not pointing you -or anyone in particular out as I am likely one of the ones involved in causing this issue. This is nothing new and has gone on for years here. Over the years I have fielded many calls & e-mails from guys here who call asking for further help because they were confused by all the different directions they were pointed too. Adding to that, I suspect there are others here that have fielded similar questions off-line after someone became overwhelmed. I am just pointing out and using this post as an example how the advice given can potentially create an issue.

 

[FlatheadTed]

I am with Mich// PA .Don't ask me how I know .Just to add ,a lean mixture can also be crud in the tank ,a leaking inlet manifold, a leaking carb mount eg warped flange .Ted

 

[Tom in SW VA]

Note to all: I will respond about the remedies suggested as soon as I can get to the garage. We have 12 + inches of snow and more is falling now. It is impossible to get the car out of the garage and to start it. Plus I have been required to travel 40 miles everyday or so to care for a critically ill aunt for whom I have medical power of attorney.


This is not the first time that I have been ridiculed on Fordbarn. It is totally unjustified and very discouraging. I was under the false impression that this was a help site. Boy, was I wrong.

On the other hand, thanks to all who have tried to help. I appreciate each of you. There are some roses among the thorns.

 

[pgerhardt]

Tom I don't think any ridicule was directed toward you or anyone else. The only critical comments I saw were those directed toward those who jump in with good intentioned suggestions without carefully reading all the previous posts and thus may add confusion rather than clarity.

Realize that everyone who has an idea will want to jump in, and if you tried all the suggestions, they may point you in different directions and drive you nuts! I read these "I need help" threads in their entirety and just look for common global points. In this case: anything that causes the engine to run too lean, or unburnt fuel to accumulate may cause back fires. That is all you need to know to start pursuing a solution.

BTW Tom your snow and ice is now heading for us in CT. be comforted by the fact that in the south - in a few days the - the warmth will return. For us up in CT there is no end in sight to this white hell of a winter! And I hope your aunt gets better soon.

 

[dennisdoornbos]

Hi Tom, did you ever resolve the backfiring through the carb? I just bought my first Model A and I am now having the same issue. Not only does it produce an incredibly loud backfire, it is spitting gas all over the exhaust when it does.

I have looked into the timing and the carburetor.

 

[Rob Doe]

Hi Tom, did you ever resolve the backfiring through the carb? I just bought my first Model A and I am now having the same issue. Not only does it produce an incredibly loud backfire, it is spitting gas all over the exhaust when it does.

I have looked into the timing and the carburetor.

I had a similar issue when first receiving our coupe. I had gasket leaks at the bottom of the cap and main jets. This was resolved by installing the black gaskets that Brattons sells. Good luck.

 

[BRENT in 10-uh-C]

Hi Tom, did you ever resolve the backfiring through the carb? I just bought my first Model A and I am now having the same issue. Not only does it produce an incredibly loud backfire, it is spitting gas all over the exhaust when it does.

I have looked into the timing and the carburetor.

I had a similar issue when first receiving our coupe. I had gasket leaks at the bottom of the cap and main jets. This was resolved by installing the black gaskets that Brattons sells. Good luck.

I am not Tom but from what I remember, the issue was the upper plate was very loose within the groove of the distributor housing and the plate was not staying centered during spark timing adjustment. As the upper plate was being rotated during timing adjustment, it would intermittently lose the electrical ground which was causing raw fuel to fill the manifold and exhaust. The problem was corrected. Tom's car was driven quite a bit after that until a young lady didn't stop quick enough causing some trauma to the car. The car has received a complete rebuild and Tom should be out 'styling' in it this Spring.

 

[jeepguy1948]

This may not be your situation but here is what happened to me.... When I first got my A I didn’t yet know the in and outs of them I had “backfiring or whatever you choose to call it coming out the carb. It turned out that the points rubbing block had worn down and the points were hardly opening and this situation causes big time retarding of the timing. Just my experience.