Vacuum advance: USE IT! - Page 3 - Vintage Mustang Forums
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post #31 of 34 (permalink) Old 08-16-2017, 12:06 PM
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Originally Posted by zray View Post
Even with a Ford Autolite distributor you can limit the total timing:

restrict the total advance the distributor is capable of by reversing the weights (if it's a stock Autolite distributor), so the more narrow advance slot is being used. Example: if your distributor is now using the 15L slot, you can reverse the weights and use the 10L slot. Your distributors numbered slots may vary, but one will be less than the other one, and the lessor one is what you want to be using in order to limit overall timing a bit more. This switch to the more narrow slot will let you have more initial advance without yourtotal timing being too excessive

Or you can put a small section of tiny rubber hose (like windshield-washer hose) over the pin that limits the advance. Either of these two methods results in the same general outcome., less total advance.

I've got a Petronix ready to run billet distributor. I do have their advance limit "thingies", but I don't trust them. They slip over the advance spring mounts and supposedely limit the travel of the advance mechanism. To me they fit sloppy and when checking with my timing light got some weird results.
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post #32 of 34 (permalink) Old 08-16-2017, 01:33 PM
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Originally Posted by SacBill View Post
Interesting article I was recently digesting on the differences between applying ported- vs. manifold vacuum. Written by a former GM/Chrysler engineer: Ported vs. Manifold Vacuum
That's a good article. I've seen that before.

It's been a while since I've seen you here. Good to see you.


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post #33 of 34 (permalink) Old 08-16-2017, 01:49 PM
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Originally Posted by sixtysevenGTconv View Post

How's that? lol
Better than me. All I had was that I'm too lazy to swap over. Kind of hard to build on that.
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post #34 of 34 (permalink) Old 08-17-2017, 12:12 AM
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Well, I tried it. I moved it from ported over to full vacuum. interesting results, at least to me, admittedly still not understanding it fully. It races and I hear some sputter out of the exhaust while it is on the idle cam. Once it comes off the idle cam it is incredibly smooth and if I closed my eyes I could swear it was a prius running. But once I hit the gas you hear the normal 289 exhaust note. Drove it around for a while and cannot tell in difference in power or sound once off idle. But you stop at a light and I can barely hear it.

When it is idling in the garage I still hear a sputter in the exhaust every 3 or 4 seconds. It may be due to having the initial timing set pretty high? Need to play with it some more, but definitely interesting.

1966 Coupe / 289 4bl
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