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Chronic lean condition please help #744854 07/10/10 05:12 PM 07/10/10 05:12 PM
Joined: Sep 2007 Posts: 125 IN 6 67Dart383 OP member
67Dart383 OP member 6 Joined: Sep 2007 Posts: 125 IN	I got a 67 Dart 383 10.0 motor mild cam ported polished 452 heads. I got a 750 holley with a proform body. The plugs are white no matter what I do. Right now it has 82 jets in the front and 91 in the rear and the plugs are still white. The idle mixture screws are backed out more then normal to get 12-14 pounds of vacuum. It acts like its got a vacuum leak but I have poured carb cleaner all over the intake and also used a propane torch around the intake with no changes. Anybody got any suggestions on what is going on?

Re: Chronic lean condition please help [Re: 67Dart383] #744855 07/10/10 05:17 PM 07/10/10 05:17 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	If you are sure you have no vacuum leaks, you might want to go a range or 2 colder on the plugs. The new alchol ladin fuel doesn't color plugs well. Fastest 300

Re: Chronic lean condition please help [Re: 67Dart383] #744856 07/10/10 05:55 PM 07/10/10 05:55 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Lean at what point... idle , mid, top end

Re: Chronic lean condition please help [Re: MR_P_BODY] #744857 07/10/10 07:41 PM 07/10/10 07:41 PM
Joined: Sep 2007 Posts: 125 IN 6 67Dart383 OP member
67Dart383 OP member 6 Joined: Sep 2007 Posts: 125 IN	Plugs show its lean all the time. I have pulled plug after its idled awhile and after making a pass at the track.

Re: Chronic lean condition please help [Re: 67Dart383] #744858 07/10/10 07:43 PM 07/10/10 07:43 PM
Joined: Jan 2003 Posts: 32,394 Q Quicktree I Win
Quicktree I Win Q Joined: Jan 2003 Posts: 32,394	thats because the white porcelain has nothing to do with being lean or fat. NOTE> If the base ring has a full turn of color with some spots of heavy dry soot, then jetting is too rich, REGARDLESS, if the porcelain is "BONE-WHITE", jetting is still TOO RICH !!! NOTE> Do not look at the porcelain to read jetting !!!

Re: Chronic lean condition please help [Re: Quicktree] #744859 07/10/10 07:44 PM 07/10/10 07:44 PM
Joined: Jan 2003 Posts: 32,394 Q Quicktree I Win
Quicktree I Win Q Joined: Jan 2003 Posts: 32,394	http://cochise.uia.net/pkelley2/sparkplugreading.html

Re: Chronic lean condition please help [Re: 67Dart383] #744860 07/10/10 07:57 PM 07/10/10 07:57 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Also make sure the brake cleaner/carb cleaner is flammable ... I just went through this with a non flammable spray(it wont rev up cause its not burning) if its that lean you really didnt make a pass... how is the supply(filter and pump)have you done a flow/ volume test

Re: Chronic lean condition please help [Re: Quicktree] #744861 07/10/10 08:03 PM 07/10/10 08:03 PM
Joined: Jan 2007 Posts: 3,695 nc E emarine01 master
emarine01 master E Joined: Jan 2007 Posts: 3,695 nc	thankx Quick Interesting read, I little different than others I have seen

Re: Chronic lean condition please help [Re: emarine01] #744862 07/10/10 09:34 PM 07/10/10 09:34 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: thankx Quick Interesting read, I little different than others I have seen and there is plenty others out there with their own interpretations. Notation in red eliminates reading plugs for about 80% of the people on this sight - including me. I'll admit, interesting reading though. Fastest 300

Re: Chronic lean condition please help [Re: 67Dart383] #744863 07/11/10 12:30 AM 07/11/10 12:30 AM
Joined: Feb 2005 Posts: 5,221 Branson, Mo. J joedust451 super gas
joedust451 super gas J Joined: Feb 2005 Posts: 5,221 Branson, Mo.	Quote: I got a 67 Dart 383 10.0 motor mild cam ported polished 452 heads. I got a 750 holley with a proform body. The plugs are white no matter what I do. Right now it has 82 jets in the front and 91 in the rear and the plugs are still white. The idle mixture screws are backed out more then normal to get 12-14 pounds of vacuum. It acts like its got a vacuum leak but I have poured carb cleaner all over the intake and also used a propane torch around the intake with no changes. Anybody got any suggestions on what is going on? If you don't have a vacuum leak & rule that out, upping the main jetting does nothing for the idle curcuit, sounds like you need to either increase the IFRs size or decrease the IABs, your main jets are WAY too fat now, start off with the factory PF recammendation jetting for the 750, should be 74/82, then after you get the idle curcuit currected, then jet for "best" mph at the track. 75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU

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