Bus back firing randomly at idle

[ElyNV_79VWbus]

I've got a 1979 bay window bus with a single weber progressive carb.
The bus has run fine for years even after sitting all winter. I started her up this afternoon and she idles ok a bit high around 1200 (normally around 1000)but backfires at random.
I am thinking old gas might be causing issues but i have never had this happen before. Maybe the electric choke is stuck on? I changed the points out for an electronic ignition years ago do they wear out over time (pertronix)
I put in fuel treatment in the fall.
thanks for your help and ideas
David

[SGKent]

check for a vacuum leak. Don't forget the brake booster.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[ElyNV_79VWbus]

I checked the brake booster, cut the ends off the vacuum line to the distributor to make them snug, ended up being loose intake runner boots. Snugged them up and she runs like a dream. I must have had a little leak for awhile.
Thanks for the help.
David

[nicketynick]

"intake runner boots"??? Where do I find this? Mine is doing exactly the same thing all of a sudden......

[nicketynick]

I have the dual Solex carb engine. I see the intake immediately under the carb has a bit where vacuum tubes come off. I notice that on both sides these things have been wrapped in tape. Quite old tape, on the left side the tape is falling off. This thing is new to me, so still on the learning curve!
Suggestions appreciated!
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73 P39 Westy
[url=https://www.vw-mplate.com/mplate2-56778.png]Click to view image[/URL]

[chuckpolzin]

i had a brand new pertronix ignitor III with the proper low ohm coil, proper plug wire set etc run like absolute garbage on me, could be some voltage drop issue but i could not get the damn thing to run properly out of the box which was frustrating, she would idle but it was pretty erratic, timing was dancing all over the place with the timing light on.

i swapped it out for a rebuild german SVDA from sparxwerks here and it ran beautifully.

I would have a spare points and condenser dizzy to try if you can get one, even the cheapies at auto zone flaps etc should tell you if its a dizzy issue. i had a cheap 009 in mine from a flaps store and it ran fine and way better than the pertronix. Not saying its the pertronix but they certainly can and do go bad.

[Wildthings]