Pulsating RPM 1971 bus

[bug_n_67]

I have a 1971 bus with the 1600 dual-port engine, I have the matching carburetor and dual vacuum advanced distributor for this bus but I can't seem to get it to idle at a constant speed. I've checked for air leaks I've set the points, the valves are set. On cold start it chokes and runs as it should but once it's warm I have a pulsating RPM, it will idle at about 850 RPM for about 30 to 45 seconds and then the RPM will increase to about 1300 and then once again it will go back to about 850. I have set up the timing with a strobe to the best of my ability reading the instructions on how to do it for this model but I just can't seem to eliminate RPM fluctuating at idle. What should I be checking next.

[busdaddy]

Does it repeat the symptom over and over perpetually?, or just once after closing the throttle?
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[aeromech]

Try a different distributor. Almost anything. See if it changes
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Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
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Capable of leaping tall buildings in a single bound

[bug_n_67]

No, it does it continually as long as it's sitting there running. I just kind of did a test and I plugged both vacuum lines from the distributor at the carburetor side and it idles fine without that pulse happening. So would it be something wrong with that distributor. I'm pretty sure those lines are hooked up right, the one coming out of the front of the canister goes to the port at the front of the carb and the one at the rear of the canister goes to the side port of the carb.

[bug_n_67]

Sorry said that wrong, the gose on the front of the canister gose to the side of carb and the one on the back goes to front of carb.

[bug_n_67]

Well I pulled the distributor and I put I knew one in that I had kicking around and guess what the problem seems fixed Plus I was having some hesitation it just seemed to lack power when you stepped on the gas and that seems to have disappeared as well so I'm guessing all that money I spent on this distributor to match it up with the carb has a problem with it.

[aeromech]

_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[NASkeet]

[busdaddy]

[bug_n_67]

Based on what you said I did have them hooked up correctly. With the new distributor in the problem seems to have gone away if so right now I'll stick with that.
And that would be Essex Ontario Canada just in case you wanted to know.

[NASkeet]