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Author
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Topic: spark advance
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 02-27-2006 11:03 PM
 
I've got a 1986 f-250 2wd that I use as a work truck/winter beater. I put a recon engine in it a couple years ago along with a crane cam.when I put the engine in I "experimented" with the emissions devices.One of the things I tried was blocking the vacuum line to the distributor advance.After checking the base timing I connected the dist. advance line directly to a ported vacuum source on the carb.When I brought the engine up to approx. 2500 rpm the timing advanced to 60 yes 60 degrees btc. I've tried two different distributors from auto zone, both advanced to 60 degrees.I'm sure that this distributor was originally designed to be used with a restrictor in the vacuum line, which would limit the amount of vacuum and therefore the total amount of timing. The question I have is ... does anybody know what distributor I could use that has total timing w/vacuum advance connected in the 34-38 degree range? At 60 degrees of total timing it sounds like the pistons are swapping holes.Thanks, Mark (engine is a 351w) [This message has been edited by Mark Ugrich (edited 02-27-2006).]
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MLariviere
Moderator Posts: 4235
From: Biddeford,Me.USA
Registered: May 99
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posted 02-28-2006 12:06 AM
Have you tried ported vaccuum to see how it runs?
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 02-28-2006 01:01 AM
quote:
Originally posted by MLariviere:
Have you tried ported vaccuum to see how it runs?
that's when the timing goes to 60 degrees, pistons rattle. The engine actually runs very good with the vacuum advance disconnected, I'm looking for a little better gas mileage and if I can find a distibutor with the right advance curve I think the mileage will improve.I'm thinking possibly an earlier version of duraspark distributor might be what I'm looking for.
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drof84
Journeyman Posts: 5
From: gillette
Registered: May 2006
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posted 05-12-2006 06:16 PM
i have a 1984 f250 with the same 351w in it. the dist, that i have advances about 38 degrees. it does not have any orifices in the line.its hooked directly to the carb.
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-18-2006 08:05 PM
quote:
Originally posted by drof84:
i have a 1984 f250 with the same 351w in it. the dist, that i have advances about 38 degrees. it does not have any orifices in the line.its hooked directly to the carb.
That sounds more like it!I'll check it out.Maybe the 1986's just do that!  Thanks, Mark
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