adjustable vacuum advance canister....1986 258 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 05-21-2005, 09:47 AM Thread Starter
 
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adjustable vacuum advance canister....1986 258

I am trying to find a source and/or a part number for an adjustable vacuum advance canister for my stock distributor on a 1986 258 CJ7. I ordered one from Summit Racing and it is close but not correct. Since doing the Nutter Bypass (ie no computer) the vacuum advance in the mid range cruise range is to much causing a ping/detonation. I have run with and with out the vacuum advance and I can make the ping go away.

Thanks
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post #2 of (permalink) Old 05-21-2005, 11:09 AM
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Re: adjustable vacuum advance canister....1986 258

A couple of cures -
Convert to an HEI - easy, very effective - then use an adjustable advance to get it dialed in. See the other post this morning about how to dial it in.

Or - with what you have -- make a little limiter stop inside the distributor to limit the travel of the breaker plate. It takes a little creativity. Max - total advance should not be more than 35 @ 3000. And it should come in slowly and evenly.
Use PORTED VACUUM.

IF you have the Ford type distributor that has a big hex nut on the diaphram, it's adjustable for sensitivity too.
Remove the hex nut - use washers as shims on the spring, or remove some. Removing them makes it LESS sensitive - puts more spring against the vacuum.

Instead of using the original carb and "Nuttering it" best to replace it altogether. The "Nutty" way is just setting it to full rich all the time - Mickey Mouse! At todays gas prices, one tank wasted will buy a nice used MC2100.
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post #3 of (permalink) Old 05-21-2005, 09:11 PM Thread Starter
 
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Re: adjustable vacuum advance canister....1986 258

Already have the MC2100 installed. I just can't get rid of the ping. I have an innovate motorsports air fuel meter and I am dialed on the fuel delivery side.
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post #4 of (permalink) Old 05-21-2005, 10:03 PM
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Re: adjustable vacuum advance canister....1986 258

A meter reading is good - sometimes it will get you in the ballpark.

But -- there's only ONE way that will tell you whether or not the AFR is right FOR YOUR ENGINE.

Use search/use the propane trick at ALL speeds.
You can do it on the street - better yet - if you have a dyno you can do it there.

It's just Reality vs theorey. And - cheaper too.
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