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Wed Mar 12, 2003 2:40 pm

1973 bus, stock engine, carbs, and dizzy.
while accellerating the bus feels fine. but if i want to just cruis at one speed, the engine will surge up and down. i am guesing it has something to do with the vacume advance. i did the suck test and it seemed to hold. the other thing i could think of, was the vacline from the carb to the dizzy does not go up to this little can on top of the engine compartment, where i think it used to go.what would this can be and what would its purpose be?
thanks for any help.
lc

Wed Mar 12, 2003 4:08 pm

The little can on top of the engine compartment is your charcoal canister. The vac-lines are 11 mm. These lines only went to your air cleaner and to your fan housing. On my 72 there is a little valve right next to the heater fan (left side). It is a advance cut -off valve. When you hit 4th gear there is a switch that activates this valve and stops the advance. Mine is not hooked up. I really don't know why it was used (anybody anybody) I don't know if the 73 had one or not. It does sound like a vacuum leak or distributor problem.
Jeffro

Wed Mar 12, 2003 6:18 pm

Ooops, I mean 12mm breather lines and not 11mm vac-lines.
Jeffro

Thu Mar 13, 2003 7:37 am

yes that is what i am talking about. not the charcole filter. so i dont need it hooked up? your bus runs fine? any suggestions on what the surging only while cruising could be? possibly the carb?
thanks

Thu Mar 13, 2003 5:20 pm

After it's warmed up and idling, CAREFULLY spray carb cleaner around the carbs and if engine runs noticeably better and smoother, It's time to rebush throttle shafts and crefully o/haul carbs if possible. If you don't drive in 30F or colder areas and don't need chokes, you may be better off running dual Weber ONE barel carbs or possibly a progressive 2bbl carb se-up (although the latter take some time to get up and running well....trial and error.
Good luck.
Gordi