Rebuilt 1935 V8 has begun backfiring

[ScubaChief60]

I began restoration last June... and 85HP V8 was rebuilt completely in Dec 2022.

My '35 has recently begun random backfiring thru the exhaust when hot and under a load.

The setup is 6V and using the original helmet distributor. I replaced the condenser but coil is original. I've owned the car since 1991 and it came with 1955 plates so figure the coil is at least a 1955 model Ford Script one.

Plugs are NGK-AB6.

Ignition wires new.

Anyone been down this road...

I am suspecting a bad condenser and/or the coil needing rebuilding.

Any suggestions on someone to rebuild the coil too will be appreciated.

Thanks!

[petehoovie]

My '34 did the same - "random backfiring through the exhaust". I resolved the problem by replacing the condenser...

[Seth Swoboda]

I too think it is an ignition issue. The consenser is the easy fix. If that doesn't resolve it you might have a timing issue with your distributor.

[ScubaChief60]

Thanks for the replies! I have a spare condenser still in the box from 30+ years ago... (probably when it was made in the good ole USA still). I'll give that a try and reply back likely tomorrow. Take care!

[rotorwrench]

Ignition intermittently turning off and on will definitely cause after fire in the exhaust. Sticky valve stems can do it too. Running some Marvel Mystery Oil should eliminate the possibility of sticky valves. The condenser or a funky distributor connection may be possibilities as mentioned. The ballast resistor and Ignition switch or wiring are other things to check out.

An exhaust leak can also affect the ability to after fire.

[ScubaChief60]

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I just found this post from three years back:

Symptoms of a failing condenser:
>Degraded hi-voltage spark that appears yellow. It should be violet / blue;
>Lack of engine power due to degraded hi-voltage;
>Backfiring as condenser breaks down internally;
>Pitting of points;
>Poor gas mileage;
>Hard starting;
>Leads to unnecessary tinkering with ignition timing and carburetor;
>Eventually engine stops running / will not start.

I have these symptoms for sure:
1- Lack of engine power
2- Backfiring
3- Poor gas mileage

I'm feeling pretty good you al have solved my issue. I'll advsie once done

[Seth Swoboda]

While we are discussing this, a lean engine can also cause a backfire. Have you changed anything on the carburetor lately?

[Bored&Stroked]

Just as a warning - old condensers are frequently dried out and defective. While you can try the old one, you'd be much better off getting a new "quality" one. I'd talk to ThirdGen or CharlieNY (you'll have to search for his contact info).

I have found VERY FEW old condensers (of any make) that are good - or at least last for long.

[ScubaChief60]

Hey... I have made no adjustments to the carburetor. I have dealt with Third Gen... so will order a quality replacement from them. Maybe two or three so I'll have backups.

Thanks all!

[rotorwrench]

Back fire is the expansion of combustible gasses coming out through the carburetor. After fire is the expansion of combustible gasses in the exhaust systems just to clarify. A lot of folks call both a back fire and it is confusing to know which end were are referring to.

[alanwoodieman]

did you check for shorts inside the rotor button--have found this problem to cause what you are listing. steel shaft goes thru button and grounds out the rotor--put two layers of shrink tape on the center of shaft

[ScubaChief60]

Thanks you all for the ideas... I have had trouble finding new Condensers... all the usual suppliers show out of stock

And I never knew the difference between back fire and after fire. Mine is definitely after fire. Ill post whatever I find to be the fix.

I will remove the distributor this weekend most likely and look into this as well "did you check for shorts inside the rotor button--have found this problem to cause what you are listing. steel shaft goes thru button and grounds out the rotor--put two layers of shrink tape on the center of shaft"

[Brendan]

mabey this will help, i made the vid
https://youtu.be/0RUbKh4xds4

its me saying what i did to a model a condenser to work in my 36 Pickup

[ScubaChief60]

I REALLY appreciate this information! I just ordered the FA5 condenser from my local NAPA and I should get an email tomorrow when they have it in hand. The NAPA fitment actually advises it's a good fit for my 35 Ford Model 48 V8. $18.95 now is all it costs.

I was concerned that I'd never find a new one again.

You've made my day my friend.

I hope that you have a great Memorial Day! (... and to anyone else on this forum that reads this)

[Terry,OH]

NAPA does not make a replacement 33-36 condenser. The FA5 is for a 4 cylinder. Suggest you look into the magneto condenser often touted here on fordbarn.com it takes some modification to fit and look proper.

[Brendan]

Originally Posted by Terry,OH

NAPA does not make a replacement 33-36 condenser. The FA5 is for a 4 cylinder. Suggest you look into the magneto condenser often touted here on fordbarn.com it takes some modification to fit and look proper.

i modified the model a condenser, to fit in my 36, it works very well

[ScubaChief60]

I did get the FA5 today and modified it sufficiently to properly fit my '35. It did start and run OK.... it's rainy here so did not give it the full test... but so far so good. I'll check out the link about the magneto condenser too.

[ScubaChief60]

Is this the Condenser you are referring to as a Plan B for me? https://www.steinertractor.com/F4-CO...neto-Condenser

I'll give it a good test and run it up the road and back about 5 miles as soon as the weather clears and will report in. The way is started and ran... it seems that it's going to be fine as Brendan reports.

[ScubaChief60]

Just found a link from 2015 on this same subject...also regarding a 1935 V8:

https://fordbarn.com/forum/showthread.php?t=183431

I think we are on a good track.

[cmbrucew]

Here is a page from Echlin catalog Sept '82Scan 2.jpg