Hi,
72 1.7 liter
DJet
Timing set, dwell set, new plug, points and condensor.

Valves just re-adjusted and checked again.

It backfires through the throttle body...

Low power, then surges as if it cleared its throught
the backfiring again.....

HELP
Suggestions needed
Rich

Did you set the timing before setting the dwell?

valves, dwell, timing in that order, always

Rich

OK, just checking. Ya never know! Did this just start after the tune up?

did it last year, tuned it up and it went away....

Last time I removed and re-greased the dizzy, that did it finally.

Rich

Well, sometimes it just don't make any sense, but if it worked once, I'd try it again. Ya just never know!

Could be the trigger points. There's no good way to test them, though. I was having a similar problem, and my heat exchangers were loose. Torqued them all to 16ft/lbs and it fixed it right up. Have you checked the plugs? It could be running lean or rich. I can never remember which one it is that makes it backfire.

Good luck,

I always though that a backfire was cuased by the mixture in the combustion chaber being fired when the valves were open. Which would be a timming issue, or carbon build up that gets hot enough to light the mixture before it is ready.

Had the same symptoms with my car. Adjusted valves and backfiring was minimized. Then adjusted the throttle position switch and it has not occurred lately (knock on wood). Good luck

Rich

Thats because it is running too rich and extra gas is getting through that is burning off durring the spark.