Backfiring Issue

it's bad. real bad. i think the timing might be off? how would i correct this? it doesn't work in high range, either (lack of #3 cyl.) anyone know a good place to get spark plug wires, besides Kaiserwillys?
sorry about my brothers screaming.

 

by the way, the dying at the end was the choke kicking closed as a result of backfiring.

 

Might be timing, might be points. Might be a vacuum leak. Might be a lean carb mix, or a burnt or mis-adjusted valve. Could be a lot of things.

There is no way to do accurate diagnosis before a tune-up to first put everything at factory specification. Anything else is chasing your own tail and wasting money on parts you probably didn't need.

Setting points and timing is simple enough, if you follow the Factory Service Manual (FSM). It gets easy with practice, and is a good skill to have. You will just need a timing light and a set of feeler gauges. Lots of old used ones kicking around.

A vacuum gauge and a compression gauge are not real expensive, and can reveal a lot about an engine too.

 

Yep, everything Pete says.

 

X2 on Pete's list.
I'd check the points first, as they will affect the timing and coil saturation time.
you can test the plug wires for firing to ground by misting them with water.
If the idle is acceptable, and it's missing under a load, the coil could be breaking down.
Lots of good help on this site. Good luck., Ron

 

The plugs must be non-resistor.
The plug wires must be copper-core
The distributor cap must have brass connector points.
The points must have a steel helper spring plate.
Gas must be fresh, clean, and dry.
Air must be clean.
Timing is Everything | Old Jeep Carbs LLC

 

All the above x2

 

My local auto parts store sells copper cored wires. I forget if they were the kind I had to crimp the ends on or not.

 

Everything everybody else said. Also I had one doing the same, turned out to be a rocker arm.

 

what's the vacuum guage for? testing the pump? we tested the compression, and #3 read ~55 psi

we need to work on the air cleaner, was leaking oil into the carb.

new coil then?

they're new, probably need adjusted.

we have both, but can't seem to find the timing light.

 

What was compression on the other cylinders?

The air cleaner oil may foul the plugs, but should foul them all. What's the spark plug condition?

Not till easy/cheap tests are done.

Points need to be gapped correctly. Do you have a dwell meter?

If I knew where all my tools were I wouldn't multiples of things I only use on full moons.

Good luck, Ron

 

the compression on the others was about 90, and we got new plugs and gapped them. what's a dwell meter?

 

Dwell meters are used to set your points. Just clip it on the wire from the coil to the the Dist. and adjust your points thru the little window on the side of the dist cap using an allen wrench. Wanted to call the dist. a dizzy just to start the controversy again.

 

A dwell meter is used fine tune the points. If the compression is that much different, My money's on #3 cylinder. Possibly sticking/burnt valves. A vacuum gage may indicate valve/ miss fire issue. Ron

 

Tyler, as long as USPS gets the manual to you tomorrow, that will be of great help.

 

Backfiring can also cause the oil in the oil bath air cleaner to go everywhere, including into the carb, I guess.
Unless you overfilled it, or soaked the mesh with oil, it really cant get to the carb.

 

I never saw an f-head with that feature. Dwell meter is optional, feeler gauge will do the job.

Vacuum gauge can reveal a number of things about engine condition. But you already know one... the #3 cylinder, maybe a burnt or leaking valve is causing the misfiring, and a 55# reading deserves investigation.

Vac Visual: Quick Guide to Vacuum Gauge Readings - OnAllCylinders

 

Get a vacuum gauge, read the instructions, and it will help your situation. Last I looked, they are under 30 bucks from harbor freight.

 

Mmm,,, maybe. But will they last 70 years?