1931

[1931ford]

I just bought a 1931 ford. It started backing firing. I checked points and rotor gap ok. Not sure if it is timmed correct of may have too much play in distributer shaft. used you tube and Les Andrews book. I did find the exhaust gasket leaking. the compression is 68 to 70 psig in all cyclinders. can any one help me before i just easter egg. Motor is clean inside like new . I replaced gas. This problem started when i was leaving a show it was hot outside.

[Rowdy]

Condensor going bad maybe. Rod

[V4F]

check timing carefully . check for good fuel flow . check for intake leaks . good luck .. steve

***
as above replace cond.

[glenn in camino]

Re set the points @ .020. The rubbing block wears a bit when they're new. They may be closing

[Kurt in NJ]

The condenser can cause it ---buy an A&L burnout proof one
The exhaust leak can also cause exhaust explosions (sound like "backfire"but out muffler) ---at times there is a vacuum in the exhaust, that draws air into through the leak, unburned fuel ignites making a sound like backfire
Too lean can cause backfire out carb--

Does it happen mopre when accelerating, at cruise, or coasting?

[Mike V. Florida]

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Originally Posted by 1931ford

Not sure if it is timmed correct of may have too much play in distributer shaft.

Rotational play is not so bad but lateral play is bad. Can you move it back and forth?

Here is an excellent lesson on timing,

www.abarnyard.com/workshop/timing.htm

[Patrick L.]

Yep, to all the above. Also, try loosening the fuel cap. Was there a previous problem or did this just start ? Have you asked the previous owner ?