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AIR FUEL RATIO NUMBERS

Any type of technical questions or info

Moderators: KillerRx4, orx626

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rotor_speed
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AIR FUEL RATIO NUMBERS

#1 Post by rotor_speed » Sat Aug 12, 2017 4:30 pm

hiya
I have a 13b bridgeport 4 port, weber 51 mm carb, electronic ignition.
new rebuilt engine I have done so far 500 km and just hooked up a innovative motor sports air fuel gauge with 98 bp fuel and 80:1 oil fuel ratio with locked distributor.
primary 2" headers are approx. 120" long

the rough spec numbers I have got are,

idle 10-11
cruise 10.6
w.o.t 11-12

so this means running rich then ?
what are ideal numbers ?
any info pls
thank you



rotor_speed
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Re: AIR FUEL RATIO NUMBERS

#2 Post by rotor_speed » Sun Aug 13, 2017 5:26 am

Racing beat u.s.a recommend the following 13b bridgeport,

45 venturi chokes
235 main fuel jet
165 air corrector jet
f11 emoltion tubes
300 needle valve

your thoughts on this pls ?



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2nd Gen 7
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Re: AIR FUEL RATIO NUMBERS

#3 Post by 2nd Gen 7 » Sun Aug 13, 2017 6:34 pm

really I know sweet Fuck all about this and still learning. But this is the AFR's ive collected from a few people that know more than me.

https://www.rx7club.com/haltech-forum-6 ... n-1114717/" onclick="window.open(this.href);return false;

yours sounds quite rich at idle and cruising



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Re: AIR FUEL RATIO NUMBERS

#4 Post by bumpstart » Mon Aug 14, 2017 5:22 pm

it is running between 11 and 12 :1 at WOT and this indicates the main circuit jetting is on the safe side of perfect and if you was to chase the idle or cruise there is every chance you may push this out
also . bridgeports can give misleading AFR at low revs or part throttles due to overlap drawing a significant amount of unburned mixture straight from the inlet

this may make them indicate at part throttles, leaner than they actually are . i tend to trust only the WOT numbers

idle wise. you can play the idle jet from 70 down to 65 or 60 / usually the f10 is a 120 holder and it is left unmolested
adjust the screws for balance. adjust for strongest idle vacuum .. lock the dizzy and adjust it to suit best power at 6K

cruise wise . running on the progression it may require the 3 hole mod and you can play where the main circuit starts to draw by adjusting the air jet// bigger air jet means earlier overlap of the main onto the progression circuit

as such . i would try one lesser on idle jet . i would try a bit smaller on air jet . i would leave the 45/ 235 on F11 right there


when the going is hard, don't retard, remember your lubrication
27 years of rotary DIY
tech forum is for tech questions.. private message box is for private messages
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rotor_speed
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Re: AIR FUEL RATIO NUMBERS

#5 Post by rotor_speed » Tue Aug 15, 2017 7:03 pm

thanks for the great info help bumpstart cheers :)



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