Where to connect vacuum advace on carb?
#1
Racer
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Member Since: Sep 2000
Location: Richmond, VA.
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Where to connect vacuum advace on carb?
I have my engine running, but it doesn't seem right. After warm up it needs to be set at 1500 rpm's to idle. Any lower and the rpms slowly drop untill it stalls. I have the stock Q-Jet, where should I hook up my vacuum advance from the distributor? To what port on the carb?
Just a refresher, I do need to remove and lug the vacuum line from the distributor when setting timing at idle, is that right?
Thanks, Steve.
Just a refresher, I do need to remove and lug the vacuum line from the distributor when setting timing at idle, is that right?
Thanks, Steve.
#4
Melting Slicks
Re: Where to connect vacuum advace on carb? (snb73)
I had quite a time getting mine right,and found a few things out during the process.With the lumpy cam I have the ONLY way I got a 650 rpm idle was with the distributer vacuum advance plugged into a full manifold port. Just pull the line and stick your finger over the end and at idle you'll feel the suction.When connected to the ported source,the car would idle irratically,then stall.The other thing I learned is that the power valve in the Q-Jet is not calibrated for a low vacuum signal. The way it works is the engine vacuum sucks against a spring,and pulls the valve shut. This will cause the idle circuit to lean down. By have a lumpy cam,there's not enough vacuum to pull the valve shut,and so the idle circuit richens the mix.We're talking tears in the eyes rich if your standing behind the car.
Anyway there's springs you can try to adjust the power valve if need be,but start with the manifold vacuum source.And yes,the timing must be set with the vacuum can disconnected,and the line plugged.Also idle speed must be as low as you can go before stalling,so the mechanical advance doesn't begin to advance. :cheers:
Anyway there's springs you can try to adjust the power valve if need be,but start with the manifold vacuum source.And yes,the timing must be set with the vacuum can disconnected,and the line plugged.Also idle speed must be as low as you can go before stalling,so the mechanical advance doesn't begin to advance. :cheers: