Hook up vacuum advance quadrajet

If your car is equipped with a blower or turbo, it is still perfectly OK to connect your vacuum advance. The vacuum advance does not know the.
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To set mechanical advance adjust the springs and weights inside the distributor to have full advance to desired setting by roughly 3, rpm. How do you determine the vacuum advance timing? What are some good numbers to shoot for on the advance, mechanical and initial timing?

Find More Posts by mlouderback. I you have points make sure your dweel is at 30 deg before setting timing. When setting your timing its with the vacuum adv disconnected. The vacuum adv can be connected to manifold vacuum and as you noticed it will bring the idle up. All you have to do is adj your curb idle screw down to the desired rpm with the adv connected.

Quadrajet Vacuum connections

The vacuum adv will add approx deg btdc. You can measure this by checking the timing with the line connected vs with the line disconnected at idle and subtract the value of the non connected reading from the connected. Your mechanical timing rpm with vacuum disconnected is your total mechanical adv, it should be somwhere around 32 - 36 deg btdc.

I hope this helps. Leaving vwcuum unplugged is akin to throwing free engine efficiency adcance down the drain. I can tell you the factory used a basic rule of thumb to determine which port the hose was connected to. Where do you find these old posts? Old Dec 31st, 11, 5: Old Dec 31st, 11, 2: How to Rebuild a Holley cfm Carburetor.

Can you please clarify that point for me? What actually happens is that the air and fuel mixture take time to burn. If you are careful while pulling it up you should be able to feel when the gears clear. The small port on the rear is a good place for the modulator.

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Resetting the idle speed will make the idle mixture screws more responsive because you are closing the primary throttle blades which permits less air and gas to by-pass the idle circuit. Again, this means the mixture burns slower and needs an earlier spark to optimize the burn. You are openning a can of worms! You can check this by watching the distributer rotor while rotating the crankshaft with a breaker bar. Thanked 3 Times in 3 Posts. Originally Posted by fwillison. Send a private message to mapman.

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But I still don't know which are ported and which are full manifold vacuum if any on the carb. Plus, what is the vacuum pipe just below the choke pulloff, as in this pic: Thanked Times in Posts. The right-side fitting on a Q-jet is manifold vacuum. That is the only time there is a difference in vacuum level on those ports. Tear a small piece of paper dime sized or smaller and with the engine idling, place the paper over the end of the port.

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Find More Posts by 7T1vette. There is only one ported nipple on the carb. If you have identified it, then all other ports are manifold vaacuum - you can hook up to any of them. The number and location of nipples varies by carb number, but if you have a Q-Jet, it likely has a long nipple sticking out on the passenger side in the choke linkage area. This is convenient for distributor hookup. But you can use any other nipple except the one ported nipple.

Everything You Wanted to Know About Vacuum Advance and Ignition Timing

Send a private message to lars. Find More Posts by lars. Thanks Lars and 7T1vette. The nipple identified on the pic at the choke linkage seems to be what Lars references. I'll double check with my vacuum gauge and then hook my vac advance to that nipple. Everyone else still seems to have theirs hooked up to ported vacuum, which is the stock connection.