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A bit lean ? #2516263
07/02/18 08:10 AM
07/02/18 08:10 AM
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Posts: 2,457
Sydney,Australia
tex013 Offline OP
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tex013  Offline OP
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4 plugs are right hand bank , single plug is #3 cylinder . All plugs look the same .
This is ater racing saturday then 1 hour run home down freeway and some regular street traffic . AFR on way to track was 13.4-13.8 range . Data log showed high 13s on strip .
1050 dominator 82F 98R jet . .069 iab , 0.032 ? hsab

Tex

20180702_190701.jpg20180702_191852.jpg

New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2516299
07/02/18 11:25 AM
07/02/18 11:25 AM
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Wind Gap,Pa.
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Sammy Offline
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Re: A bit lean ? [Re: Sammy] #2516350
07/02/18 01:19 PM
07/02/18 01:19 PM
Joined: Jan 2007
Posts: 8,027
Mt Morris Michigan
mopar dave Offline
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I agree or too cold of plug. The base ring is very dark indicating rich. You want the color change on the ground strap on or near the bend for proper timing/heat range. I dont believe the insulator tells much without cutting the thread shell off,except detonation if you have black specks.

Re: A bit lean ? [Re: tex013] #2516375
07/02/18 02:10 PM
07/02/18 02:10 PM

C
crabman173
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crabman173
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Heat range ok --work on timing leave fuel alone until you get timing where color change is at the bend then see
BTW If you call NGK tech line they answer on first ring and even if the tech is female they will NAIL heat range IF you know your exact CR
They have the best plugs and best tech in the industry bar none

Fuel curves are all over the place depending on throttle blade position, intake type etc You gave it a work out in every arena--Race wide open hard, street cruise, stoplights etc Big RPM with a dual plane intake will shock you on the dyno when a few cylinders lean out--stagger the jetting and you are cool for Making another pull on the dyno but is that what you need tooling around? It all gets complicated---

Carbs get blamed for most if not all distributor / timing issues It is the gold standard of hot rod misdiagnosis

and...hey could be rich LOL

Re: A bit lean ? [Re: tex013] #2516392
07/02/18 02:32 PM
07/02/18 02:32 PM
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Bend,OR USA
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Cab_Burge Offline
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I like what I see on your plugs up
I would tune for best MPH at the track for WOT on new plugs installed there and then look at your cruise AFR on the way home twocents scope
I like and shoot for 14.5+ AFR at light part throttle cruise to help keep the plugs clean, you can lean that circuit down and then increase the WOT mixture through the rear jets or power valve restriction channel work up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: A bit lean ? [Re: tex013] #2516407
07/02/18 02:47 PM
07/02/18 02:47 PM
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Oregon
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AndyF Offline
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Is that pump gas? The sooty deposit looks like pump gas. If that is race gas then it is rich but that looks normal for pump gas. Plug might be too hot based on how far down the threads the heat goes. What number is that? I agree with talking to NGK tech, they are really good.

If you are high 13's going down the track then you are too lean for max power. Just depends on how much you trust the AFR data.

Re: A bit lean ? [Re: tex013] #2516458
07/02/18 03:55 PM
07/02/18 03:55 PM
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State of confusion
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Thumperdart Offline
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I'd run a .026-.028 on the high bleeds for starters and watch the curve go richer in the mid and top end high load zone..........


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: A bit lean ? [Re: tex013] #2516494
07/02/18 05:31 PM
07/02/18 05:31 PM
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New York
polyspheric Offline
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Fuel curves are all over the place depending on throttle blade position, intake type etc

YES, + manifold vacuum


Boffin Emeritus
Re: A bit lean ? [Re: tex013] #2516545
07/02/18 07:42 PM
07/02/18 07:42 PM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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ok thanks guys
Plug is NGK BKR6E gapped at 0.035
98 pump gas , no ethanol or additives
Thumper , that is what I was thinking to pull harder on jetting
Timing was set on chassis dyno running timing loop , is 20deg initial plus 16 all in at 2500ish

thanks again . Will see if ican put up the afr log picture
See around 2 minute mark


Tex

06301800-Session 3.txt (54 downloads)
Last edited by tex013; 07/02/18 08:31 PM.

New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2516575
07/02/18 08:36 PM
07/02/18 08:36 PM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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tex013  Offline OP
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Try this

Tex

20180703_083543.jpg

New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2516586
07/02/18 09:01 PM
07/02/18 09:01 PM
Joined: Jul 2004
Posts: 19,317
State of confusion
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Thumperdart Offline
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Originally Posted By tex013
ok thanks guys
Plug is NGK BKR6E gapped at 0.035
98 pump gas , no ethanol or additives
Thumper , that is what I was thinking to pull harder on jetting
Timing was set on chassis dyno running timing loop , is 20deg initial plus 16 all in at 2500ish

thanks again . Will see if ican put up the afr log picture
See around 2 minute mark


Tex


What compression.............


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: A bit lean ? [Re: Thumperdart] #2516613
07/02/18 10:16 PM
07/02/18 10:16 PM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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tex013  Offline OP
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Thumper

between 10.9 & 11.0:1 compression

Tex


New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2516654
07/02/18 11:27 PM
07/02/18 11:27 PM
Joined: Jul 2004
Posts: 19,317
State of confusion
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Thumperdart Offline
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I'd try a #7 personally and I keep 8's clean on my Dart at 12.1.1 comp..........


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: A bit lean ? [Re: Thumperdart] #2516662
07/02/18 11:29 PM
07/02/18 11:29 PM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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hmm , ok that's something well worth trying

Tex


New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2516663
07/02/18 11:29 PM
07/02/18 11:29 PM
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Oregon
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AndyF Offline
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I use NGK 6 heat range with my pump gas engines and it works fine. I'm pretty sure if you call the NGK tech line they'll tell you 6 is fine and maybe 7 for racing.

Re: A bit lean ? [Re: AndyF] #2516867
07/03/18 01:49 PM
07/03/18 01:49 PM
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Posts: 19,317
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Thumperdart Offline
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I make my own decisions these days based on experience both good and bad and would rather error on the colder/richer side than the other way as I've seen the damage that can and will occur. Check out Mancini Racing's site and iirc they are WAY opposite as in they recommend colder than I would run at a given compression ratio so whatever works............. thumbs


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: A bit lean ? [Re: Thumperdart] #2517147
07/03/18 07:40 PM
07/03/18 07:40 PM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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tex013  Offline OP
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Originally Posted By Thumperdart
I make my own decisions these days based on experience both good and bad and would rather error on the colder/richer side than the other way as I've seen the damage that can and will occur. Check out Mancini Racing's site and iirc they are WAY opposite as in they recommend colder than I would run at a given compression ratio so whatever works............. thumbs

thanks Thump , its always a juggle . A rich motor is just that , too lean is burnt up . I know a chev I used to have liked a hotter plug in the traffic .I am just waiting to get valve covers back then I will change hsab and go from there .

thanks Andy , here in Oz only an email to NGK but they recommend #6 as long as no fouling or an Iridium plug

Tex


New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2517221
07/03/18 11:03 PM
07/03/18 11:03 PM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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Cab_Burge Offline
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On your deal I would put in a extended gap NGK #7 to be safe and easier to read while jetting twocents scope
I burnt a head gasket out when I had a lean problem way back when by switching from a NGK #7 to a NGK # 6, I had two little Holley blue fuel regulators on my old M.W. bracket car, one feeding each carb. with one fuel pressure gauge reading from one carb. only realcrazy shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: A bit lean ? [Re: tex013] #2517301
07/04/18 06:19 AM
07/04/18 06:19 AM
Joined: Mar 2009
Posts: 2,457
Sydney,Australia
tex013 Offline OP
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tex013  Offline OP
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Thanks Cab
Work in progress

Tex


New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
Re: A bit lean ? [Re: tex013] #2517795
07/05/18 02:46 AM
07/05/18 02:46 AM
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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Sport440 Offline
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I think your one step hot, and a bit rich. As cab stated jump to a 7 and adjust from there. Your secondary jets are much bigger then they should be IMO. You were probably way to rich under full throttle but the porcelian cleaned up with the drive home with the Hotter plug.


Id step down to the 7 plug and lower secondary jets a little. Id final jet it for MPH.

Last edited by Sport440; 07/05/18 02:55 AM.
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