Weber 32/36 backfiring

[18Fiatsandcounting]

On the earlier cars, if you grasp the rotor and try to turn it, all you get is a very slight backlash due to the gear connection with the exhaust camshaft. However, I think your '79 has a different style rotor and that might rotate to advance the timing based on engine speed. Something to verify which it is, though, as a distributor issue could cause the backfiring. Do you have the round plate type of rotor, or the "pointer" type rotor?

By the way, do you have electronic ignition or the old school points? If the latter, single or dual points? I know the dual points were used from the mid 70s up through 1978, and it's tricky to get both sets of points timed right. Which set of points is used depends on engine temp. A weird setup, but it was one of those head-scratcher emission control items.

-Bryan

[Anbele]

I have the round flat plate type. One more thing, what are the symptoms of bad ignition coil. I’m pretty sure I have the original one. Do they go bad just by “seating unused”…I understand PO had the car parked in a garage for 5+ years.

[Anbele]

Happy to report that it seems that the distributor was the culprit of my backfiring…I install a new one from AR—swapped the magnetic pitck up coil though for a Magnetti Marelli one; the one supplied with the distributor was under par—and Voila! Or should I say Ecco! Now, I did ALL my timing adjustments by “ear”. I don’t have a stroboscopic gun so I went for my trusty ear drums…it seems to have done the trick! I do plan to take Bambina to the mechanic for proper adjustments, but for now I can drive it without being Chitty Chitty Bang Bang.

[Nut124]

I'm glad you are making progress.

I'd be careful driving a car with ignition timing set by ear. It needs to be set and checked with a timing light. You can get a light at any car part store for $50-100.

Too much advance can lead to detonation and valve, piston damage. Too little can burn or seize ex valves.

[Anbele]

Thank you Nut124. To be honest, after having the car backfiring on me for the past three months, the smooth running now seems a blessing. But will follow advice and get to the mechanic asap.

[Nut124]

Does your mech know how to work on these old cars?

Why not get the timing light and do it yourself?

[Anbele]

Fortunately, yes! He comes from South America. Grew up with these type of engines…I’m gonna take the opportunity at the same time to change the timing belt and water pump.

[18Fiatsandcounting]

I’m gonna take the opportunity at the same time to change the timing belt and water pump.

Whether you or your mechanic, don't forget to "time" the pulley for the auxiliary shaft when changing the timing belt. With the engine at TDC on cylinders 1 and 4, and the pulleys for the camshafts lined up as required, the small hole in the pulley for the auxiliary shaft should be at roughly the 1 o'clock position as you look at it from the front.

On some engines, the lobe on the end of the auxiliary shaft can strike the #2 connecting rod if things are timed incorrectly. It's not something you want to have happen....

-Bryan

[Anbele]

Thanks Bryan. Will do.

[bobplyler]

nevermind.