Backfire

J

Jimmy VD

New member
Hi, I'm new to Ford Barn, please be patient with my question. I have a 1951 Ford woody, flathead V8. My dad bought the car new and gave it to me when I turned 16 in 1966 and said here is your car. I have had it ever since and know every squeak and rattle. It's been running rough lately and I have done everything I know to "tune" it. Last Saturday when I started it up. I forgot to turn on the key before I started turning it over. Obviously there was a lot of un-burned gas in the exhaust system. As soon as I turned the key there was a loud "explosion". From the new sound of my car, I realized that I had obviously blown a gigantic hole in the muffler (thank you Midas for another free lifetime muffler).

The question: Where do I start with the diagnosis? Obviously start with the timing. Advance? Retard? Check the vacuum system. Rebuild the carb?

Also - anyone know of a good flathead mechanic in the Orange Co., CA area?

Thanks!

Thanks.
 
How much do you know about how the distributes work on these vehicles? Sorry if I am telling you what you already know! The distributer is totally a vacuum advance unit that works off of a vacuum source in the carburetor. A possibility might be the diaphragm in the distributor, the vacuum line, the vacuum source from the carb, etc.
 
Try a new condenser. My 50 had a backfiring problem also. A neighbor said replace the condenser. It turned out that the wire in the condenser was partially connected.
 
A lot of things can cause a rough running engine. Without knowing what has already been done, it's harder to give a good course other than a complete tune up and possibly some needed fuel system maintenance. Time and modern fuels aren't kind to older automobiles. The two previous items are a good start. One being the easiest thing to check and the other being one of those things that would need to be checked when higher than normal coolant temps and poor performance show up. It could be something as simple as old fuel that has deteriorated to the point that it's noticeable.

When troubleshooting start with the easiest thing first then go on to the progressively harder checks until the problem shows up. Welcome on the Barn.
 
Be sure that you have the correct carb for the engine. The distributor advance in your car gets the vacuum from a port on the carb, itself, and not raw vacuum from the intake manifold. Backfiring after cranking without the ignition on loads the system with fuel, which ignites when the ignition is turned on and the engine cranked. It can also be caused by fuel leaking into the manifold from a faulty power valve. A backfire can rupture the diaphragm in the valve, so it is good to check your to be sure it is OK after the backfire.
 
It was an exhaust backfire. Not an intake backfire. The power valve could still be bad for other reasons. Not an exhaust backfire.


Sal
 
Welcome to the ‘Barn.....great suggestions so far....you stated you did what you know to tune it....what was that??.....when I have a new problem, I go back to the last thing I did to see if I made an error on something....ignition and fuel system maintenance is a good place to start but be methodical while diagnosing (as has been suggested)....
So, you have a ‘51 Woody that your father bought new and you’ve owned for more than 50 yrs.?!?!?!?......that’s fantastic!!...Good for you on keeping it all these years!!!....We LOVE pictures.....please!!.....Mark
 
How old are the spark plug wires? if they are old , you could be getting "leakage" out of one or more wires , causing a misfire. if this is the case, sometimes this problem can be seen at night with the eng. running, the hood open and all the lights off. some times you can see the wires arcing back and forth. the best way the average guy can check for bad plug wires is with an ohm meter, if you have one. there is usually a spec in some manuals of how many ohms per foot of plug wire is allowed. this will also depend on the type of wires. can't remember the spec's off hand . I am sure some one here knows.
 
Thanks everyone! I did put in a new rotor, condenser, coil, points, etc. a while back and it worked o.k., but ran rough. Last week I disconnected the vacuum line (as it says in the manual) and tried my best to set the timing using an old timing light that is not very bright (I ordered a new induction one that I can hook up to a 12 volt source which will be more accurate). I did find that there was no gap on my contacts and fixed that which made it better, but did not fix the overall problem. It seems to idle o.k., but starts chugging during acceleration, so I'm thinking the vacuum advance or power valve. I will work on those. By the way the carb is a fairly new Edelbrock 94 and "should" be working fine, at least it was when I installed it a few years ago.

My dad bought the car in Kermin (Fresno), CA for $2649.87 on March 10, 1951 and gave it to me in 1966, 53 years ago. I know pretty much every rattle, squeak and "her" (sorry not PC) every complaint. Sometimes "she" just decides not to start, no matter how much coaxing I use. I'm on my 3rd or 4th engine due to blown head gaskets and cracked blocks, etc. Who knows, I may be in the market for another one.
 

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Nice wagon! Are you sure the vacuum advance is working? With your new timing light you should be able to check that.
 
Boy, Is that a nice lookin' vehicle. I have the original invoice for my '51 Club coupe somewhere. I think it was almost a thousand dollars cheaper. I'll see if I can find it.
 
That's a beautiful '51 Woodie ! That was a lot of money back in '51. My Father bought a new '63 Dodge 440 with a 318 V8 for $2400. About $200 less than the '51 Woodie.


Sal
 
Jimmy VD......great looking wagon!!!...thanks for the pics!!...you’ve come to the best place for help with your car...as has been said you should see the timing mark move when you rev the motor if your advance is working. If the gap wasn’t right on the points, and the motor was run, it may have burnt them and they should be checked closely. Keep us posted of your progress.....Mark
 
Also, when it's idling, does the exhaust stink like too much fuel ? If the idle improves when you turn in the two idle mixture screws on the carb, then a good chance the power valve did go bad. Or the fuel level is too high for some reason.


Sal
 
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