A bit lean ?
#2516263
07/02/18 08:10 AM
07/02/18 08:10 AM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
OP
top fuel
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OP
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Joined: Mar 2009
Posts: 2,457
Sydney,Australia
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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
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
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Re: A bit lean ?
[Re: tex013]
#2516375
07/02/18 02:10 PM
07/02/18 02:10 PM
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crabman173
Unregistered
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crabman173
Unregistered
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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
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Re: A bit lean ?
[Re: tex013]
#2516458
07/02/18 03:55 PM
07/02/18 03:55 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
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Posts: 19,317
State of confusion
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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.....
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Re: A bit lean ?
[Re: tex013]
#2516494
07/02/18 05:31 PM
07/02/18 05:31 PM
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Joined: Oct 2007
Posts: 4,205 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,205
New York
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Fuel curves are all over the place depending on throttle blade position, intake type etc
YES, + manifold vacuum
Boffin Emeritus
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Re: A bit lean ?
[Re: tex013]
#2516545
07/02/18 07:42 PM
07/02/18 07:42 PM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
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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
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
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Re: A bit lean ?
[Re: tex013]
#2516586
07/02/18 09:01 PM
07/02/18 09:01 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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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 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.....
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Re: A bit lean ?
[Re: Thumperdart]
#2516613
07/02/18 10:16 PM
07/02/18 10:16 PM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
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Joined: Mar 2009
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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
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Re: A bit lean ?
[Re: tex013]
#2516654
07/02/18 11:27 PM
07/02/18 11:27 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
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Posts: 19,317
State of confusion
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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.....
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Re: A bit lean ?
[Re: Thumperdart]
#2516662
07/02/18 11:29 PM
07/02/18 11:29 PM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
OP
top fuel
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OP
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Joined: Mar 2009
Posts: 2,457
Sydney,Australia
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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
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Re: A bit lean ?
[Re: Thumperdart]
#2517147
07/03/18 07:40 PM
07/03/18 07:40 PM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
OP
top fuel
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OP
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Joined: Mar 2009
Posts: 2,457
Sydney,Australia
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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............. 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
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Re: A bit lean ?
[Re: tex013]
#2517301
07/04/18 06:19 AM
07/04/18 06:19 AM
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Joined: Mar 2009
Posts: 2,457 Sydney,Australia
tex013
OP
top fuel
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OP
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Joined: Mar 2009
Posts: 2,457
Sydney,Australia
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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
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Re: A bit lean ?
[Re: tex013]
#2517795
07/05/18 02:46 AM
07/05/18 02:46 AM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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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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