Re: White Plugs Burning Lean??
[Re: Cab_Burge]
#1518212
10/16/13 10:39 PM
10/16/13 10:39 PM
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Joined: Sep 2010
Posts: 114 Oakdale, MN
weazel
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Oakdale, MN
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I think the remark was to illuminate the mechanical advance dropping back from say 10 degrees BTDC to say 4 degrees BTDC when put in gear, the less initial advance will make the motor drop more RPM when put in gear One of the accepted standards on RPM drop on initial timing and the mechanical ignition curve as well as setting the carb. up to idle on the idle circuit only is to have only 200 RPM drop from nuetral to in gear with a automatic trans that has a standard non racing converter, IE idles at 800 RPM in nuetral and drops to 600 RPM in gear The less initial advance you have at idle can lead to a bigger RPM drop if the total mechanical advance has to much in it IE if you have 13 degrees mechanical(26 total crankshaft degrees) advance in the distributor and you want to have 34 degees total advance you have to set the initial at 8 degrees BTDC, but if the distributor has 3 degrees mechanical advance in it at 800 RPM and drops 2 distributor degrees at 600 RPM you end up with 4 degrees initial in it at idle, most motors don't like to have 4 degrees advance at idle They do like 12 to 16 BTDC though at a 600 RPM idle speed Is that clear Lots of ways to make are hotrod motors run better, but it requires working on and modifying some of the parts to make them better
Im pretty sure I follow you on what you mentioned. With that being said, I've always been stumped why the RPMs dropped so much with it in gear. I have already welded up the weight slots in the distributor so that it gives me 20* at the crank.
Now if Im following you correctly, because of my specific set up. When Im setting the initial with the car idling in park at say 11* and then put it into gear it may change that 11* to 5* because of the load now on the engine. So instead of 11* I should have 17* so that when its in gear its now at 11*???? Or there about?
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Re: White Plugs Burning Lean??
[Re: hp383]
#1518213
10/16/13 10:40 PM
10/16/13 10:40 PM
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Joined: Sep 2010
Posts: 114 Oakdale, MN
weazel
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Quote:
On engines that i have installed the 284/484 or the 292/509 cam, i have always installed the light weight advance springs in the distributor.
I am running 1 light spring and the factory light spring in mine, since it is not a race car.
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Re: White Plugs Burning Lean??
[Re: hp383]
#1518214
10/16/13 10:41 PM
10/16/13 10:41 PM
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Joined: Sep 2010
Posts: 114 Oakdale, MN
weazel
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Quote:
Quote:
I have pics of the plugs, but its very hard to tell the true color. I also noticed that not all the plugs where white. Some of them where actually the nice brownish color.
Also I shouldnt say that I hammered on the throttle but I did give it about half throttle to see if it would go. Otherwise it was cruising speed at 60-65.
This is a pic of the white plug.
That broken insulator is a sure sign of pre-detionation.
That wasnt actually broken, its just weird white spots on the insulator. Its actually still in good shape. I think the pic was deceiving.
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Re: White Plugs Burning Lean??
[Re: weazel]
#1518215
10/16/13 10:57 PM
10/16/13 10:57 PM
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Joined: Aug 2003
Posts: 43,223 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,223
Bend,OR USA
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Quote:
I think the remark was to illuminate the mechanical advance dropping back from say 10 degrees BTDC to say 4 degrees BTDC when put in gear, the less initial advance will make the motor drop more RPM when put in gear One of the accepted standards on RPM drop on initial timing and the mechanical ignition curve as well as setting the carb. up to idle on the idle circuit only is to have only 200 RPM drop from nuetral to in gear with a automatic trans that has a standard non racing converter, IE idles at 800 RPM in nuetral and drops to 600 RPM in gear The less initial advance you have at idle can lead to a bigger RPM drop if the total mechanical advance has to much in it IE if you have 13 degrees mechanical(26 total crankshaft degrees) advance in the distributor and you want to have 34 degees total advance you have to set the initial at 8 degrees BTDC, but if the distributor has 3 degrees mechanical advance in it at 800 RPM and drops 2 distributor degrees at 600 RPM you end up with 4 degrees initial in it at idle, most motors don't like to have 4 degrees advance at idle They do like 12 to 16 BTDC though at a 600 RPM idle speed Is that clear Lots of ways to make are hotrod motors run better, but it requires working on and modifying some of the parts to make them better
Im pretty sure I follow you on what you mentioned. With that being said, I've always been stumped why the RPMs dropped so much with it in gear. I have already welded up the weight slots in the distributor so that it gives me 20* at the crank.
Now if Im following you correctly, because of my specific set up. When Im setting the initial with the car idling in park at say 11* and then put it into gear it may change that 11* to 5* because of the load now on the engine. So instead of 11* I should have 17* so that when its in gear its now at 11*???? Or there about?
The best way to check how much advance you have idling in gear and then in nuetral is to actually check it If it is idling at 17 BTDC and then drops to 11 BTDC you might want to use two light racing springs I like to see no drop on the initial advance from in nuetral to putting it in gear I have set up distributors with the Mr Gasket old GM light springs used in Mopar distributors to have all the advance in by 1200 to 1500 RPM That works very well Idles at 1000 RPM in nuetral at 14 to 16 degrees BTDC and idles with the same amount of advance at 800 RPM in gear
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: White Plugs Burning Lean??
[Re: Dunnuck Racing]
#1518220
10/17/13 08:44 AM
10/17/13 08:44 AM
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Joined: Sep 2010
Posts: 114 Oakdale, MN
weazel
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Quote:
The 670 Street Avenger is extremely lean. I had to rework the idle circuit to get a fat enough mixture and jet up several sizes. Its bad enough on non ethanol fuel,but e10 really kills it. Keith
Do you suggest jumping a couple jet sizes at a time? Then driving it and seeing how it does? I dont have a A/F gauge so I will more or less be guessing.
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Re: White Plugs Burning Lean??
[Re: Rug_Trucker]
#1518221
10/17/13 08:53 AM
10/17/13 08:53 AM
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Joined: Sep 2010
Posts: 114 Oakdale, MN
weazel
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I also have my idle set at 800 and when put in gear it drops to about half that. I know the 268 cam has a somewhat loopy idle
No alarm bells going off here guys?
Care to elaborate with some useful info or being sarcastic about something?
400rpm? I would also like to see vacuum numbers neutral to in gear. White plugs can be a vacuum leak too. IIRC the MP distributors had 2 light weight springs out of the box. It worked good on a bone stock 383 magnum.
I can tell you that I have 14-15 with the timing and carb mixture screws adjusted in park.
Im very curious now what my timing is going to be with it in gear. I will be checking that out this weekend when I have time.
Im curious on the benefits of getting my dizzy curved? Can someone explain to me what curving it does?
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Re: White Plugs Burning Lean??
[Re: weazel]
#1518222
10/17/13 10:53 AM
10/17/13 10:53 AM
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Joined: Jan 2003
Posts: 12,154 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,154
Benton, IL.
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Your engine probably cruises on the main jet circuit, If so, then the cruise A/F ratio will be set primarily by the main jets.
The idle mix and off idle transitions will be set by the Idle Fuel Restrictors and Idle Air Bleeds. And although these circuits overlap in use, they are 2 different jetting exercises. There is another thread running now that is into this.
In my experience, the only real way to get the cruise ratio where it needs to be is with an O2 meter. The idle however, can be dialed in with listening to what the engine likes.
That is because most of our engines like 14.4-14.7 +/- cruise ratio. And I don't know how you would achieve that by driving and listening. The idle mix however is very different combo to combo, and is usually best set by what the engine combo likes.
And although there are recommended guidelines and starting points, the initial timing and the timing curve is another area where experimentation with what the combo likes is often the best thing.
Even EFI set-ups on engines with more cam overlap are often locked out at idle and settings are fixed.
On my engines, the bigger the cam, the more idle lead they want. I have 25* advance at idle on the engine in the Cuda.
IHTH
Master, again and still
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