<VV> LM ignition/distributor timing

Sethracer at aol.com Sethracer at aol.com
Tue Jul 1 00:41:34 EDT 2008


 
In a message dated 6/30/2008 9:02:20 PM Pacific Daylight Time, 
dougbee at comcast.net writes:

Any ideas what I should be looking at?  what is causing the vacuum advance to 
work at idle?

Doug Barneck
back from the national convention and having to work on my son's corvair some 
more...

The carbs are set too far open. That exposes the transfer port and the vacuum 
port and it pulls the vacuum advance open. You should be idling strictly on 
the idle circuit. Again - You should have no vacuum advance at idle. Try doing 
this. First, disconnect and plug the hose from the RH primary carb to the 
distibutor. Then disconnect the throttle link to the left side primary carb. (This 
is in the shop manual - you can just follow it there.) Then adjust both 
primary carb idle speed screws so the throttles are just closed - make sure the 
linkage is not pulling them open and chokes are not changing the throttle stop, 
pulling the throttle open. Then open each idle speed screw about 1.5 turns. 
Then try starting the motor. If it doesn't run well, bring the idle up a ways 
(adjust both screws the same amount at this point) and try to balance the two 
primaries. Do you have a Unisyn? It makes balancing the two carbs much easier. If 
not you can use a vacuum gage on the carb ports that normally pull off the 
chokes - those ports are connected directly to the manifold vacuum. You are 
trying to measure the amount of airflow through each carb and adjust it to make it 
equal on both sides. When you have equal flow, adjust the screw on the left 
side throttle link to "Just" engage the carb. Then adjust the mixture screws to 
maximize the idle RPM - without touching those idle speed screws. Once this 
is done check to see if you have any vacuum coming through the hose from the 
carb to the distributor. If you still have a vacuum there, you will have to try 
to get the idle speed down. - Seth Emerson



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