Backfiring Through Carburetor

[Bill Everett]

The picture shows the timer when the spark lever is fully retarded.

I can't seem to get another picture loaded, but it is of the timer when the spark is fully advanced; it's rubbing the belt.

Currently, the engine will run roughly on battery, but getting it started is a chore with frequent backfires through the carburetor which is a
Kingston L-4.

In order to correct the spark lever, I'm open to suggestions to bending it, or whatever is needed, to permit full range of travel.

Any help is appreciated.

Thx.

[Virtus]

If you replaced the fan belt with a shorter one would that allow the timer full travel? The backfiring through the carb is definitely a timing issue. Steve Jelf has a foolproof way of setting the timer on his website which I would heartily recommend.

[RajoRacer]

A lean mixture can also contribute to backfire.

[Norman Kling]

Lean mixture , burnt or sticking intake valve. You are getting firing when the intake valve is open.
The belt problem is either caused by the timer rod being too short, which would indicate the spark is set too advanced or the wrong belt. The usual cause is the wrong belt. There are several belt sizes due to different size pulleys on the various year cars.
Norm

[Art M]

You should consider doing a compression check on each cylinder. This is relatively easy and will tell you which direction to focus your investigation. Keep us informed.
Art Mirtes

[Scott_Conger]

Don't bend the rod "to get full range of travel"...bend it to set the timing correctly. Perhaps photo magic, but that looks FAR too advanced for starting. did you recently go from a roller to an Anderson timer? The difference in timing is pretty significant and you CANNOT use the handy-dandy timing thing-a-ma-bob that the vendors sell for setting up an Anderson...just original-style roller timers.

Getting timing correct is a start. Do that and report back.

[Charlie B in N.J.]

Bingo Art. You hit it right on the head. Compression test. First and foremost. After that you will know exactly how to proceed.

[Scott_Conger]

This post is a rehash of another post for the same exact thing. In that thread, you can see that it is a pretty darn early car, it has the correct 23" belt on it, and yet the timer crashes into the belt when advanced; at 23", the belt is not too long; it backfires through the carb. Yes, you could do a compression check, and you could check the rear axle for babbit washers, too, but every indication is that this car has a too-far advanced timer...an Anderson, no less, which is prone to this if it was just substituted for a roller timer.

In my shop, getting the compression testing equipment gathered together and installed on the engine is about 10 minutes. Testing the engine is another 5-6 minutes.

Switching on the battery, timing fully retarded, and slowly cranking the engine until a coil vibrates and then checking the crank pin to be at just barely past "3/9 o'clock" takes all of 30 seconds.

All evidence points to maladjusted timing and that is the very fastest test that can be done. Once done, if it is timed perfectly, then a compression check is in order to ensure the timing gears are meshed correctly and no valves are stuck. It is an important and useful test, but it is not the ONLY test, and given the evidence presented, is not warranted until timing is verified.

[Art M]

If it is timing causing the backfiring thru the carb, he should have been advised to check the wiring.