The Ford Barn

cjc56 · 11-02-2014, 03:30 PM

I have a 312 56 in a tbird. The distributor has a dual vac advance. When I attach the vac lines to the distributor (AT IDLE) the vac advance immediately advances the timing just a little. It causes the engine to run a little rough at idle. Once the engine is above 800 rpms it seems to run fine. My question is, should the timing be advancing at all during idle? And if Not does this mean that the return springs need to be replaced or adjusted. If they need adjustment, can some one tell me how to do it?

ponymare · 11-02-2014, 04:07 PM

Do you have the line hooked to a timed port on the carb?

cjc56 · 11-02-2014, 07:55 PM

This vac advance has two diaghrams(one on top of the other) that has a line going to each. Therefore there are two lines going to the VAc Advance. One line is for carb vac and one is for manifold vac. Both are connected properly.

Daves55Sedan · 11-03-2014, 04:34 PM

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If I remember correctly, the springs attach to a cam in the distributor. the cams need to be turned to the exact right spot to provide the correct amount of spring tension. If they are a little off in either direction, it will mess up the timing of your spark.

11-02-2014, 03:30 PM	#1
cjc56 Senior Member Join Date: May 2014 Posts: 123	distributor return spring adjustment I have a 312 56 in a tbird. The distributor has a dual vac advance. When I attach the vac lines to the distributor (AT IDLE) the vac advance immediately advances the timing just a little. It causes the engine to run a little rough at idle. Once the engine is above 800 rpms it seems to run fine. My question is, should the timing be advancing at all during idle? And if Not does this mean that the return springs need to be replaced or adjusted. If they need adjustment, can some one tell me how to do it?

11-02-2014, 04:07 PM	#2
ponymare Senior Member Join Date: Sep 2014 Posts: 160	Re: distributor return spring adjustment Do you have the line hooked to a timed port on the carb?

11-02-2014, 07:55 PM	#3
cjc56 Senior Member Join Date: May 2014 Posts: 123	Re: distributor return spring adjustment This vac advance has two diaghrams(one on top of the other) that has a line going to each. Therefore there are two lines going to the VAc Advance. One line is for carb vac and one is for manifold vac. Both are connected properly.

11-03-2014, 04:34 PM	#4
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: distributor return spring adjustment Sponsored Links (Register now to hide all advertisements) If I remember correctly, the springs attach to a cam in the distributor. the cams need to be turned to the exact right spot to provide the correct amount of spring tension. If they are a little off in either direction, it will mess up the timing of your spark.