vacuum advance with weber operation

[duster97]

I was tinkering around with my timing and air/fuel mix today and came across something I wanted to ask you guys. I have a 32 36 progressive weber. I read the thread about what vacuum lines to hook up to it and followed it to a t. I was resetting my timing to 5 btdc for emissions and noticed when I would plug the the hose back in to the advance unit on the dizzy my timing would jump from 5 btdc to 20 btdc. I found this odd because the fsm states it should only advance it to 13 btdc. So I plugged off all vacuum hoses and ran the weber bare. I got it set to 5 btdc. It no longer advances since thr lines are plugged off. and now my mixture screw in the weber is running best lean idle at about 1 and 3/4 turn out which is exactly within the parameters of the redline documentation where as before I plugged off all the advance hoses I had to have the mixture screw put approx 3 turns to keep it from sputtering and running like crap.

A malfunctioning advance unit perhaps? Wanted to see what you guys think.

[dlb]

it sounds like you just mixed up the upper and lower advance ports. the lower one advances the timing by about 13* while the upper one advances about 8*. the lower port should be connected to ported vacuum which has no effect at idle, and the upper port should be connected to manifold vacuum which is present at idle.

i would correct the advance unit hoses and then try resetting the idle mixture. if the screw still needs to be out too many turns, i would then change the jets.

[duster97]

I have two upper ports which are tied together with a y and that goes to my gas filter. The single lower port is routed to the vacuum port on the weber.

[dlb]

I have two upper ports which are tied together with a y and that goes to my gas filter.

why is this? if the upper can has two ports and you are not using the HAC system, you should just plug the upper port with the small hole and connect the gas filter to the port with the big hole. see if this corrects your timing at idle. i don't think it will but try it anyway.

besides splitting manifold vac to the two ports on the upper can, it sounds like you have the vacuum routing correct.

[duster97]

The plastic y was there when I purchased it. I'll try plugging the one like you said and see if that changes anything