quadrajet 455ho

[ss3011]

Originally Posted by Jeff Stout

I always thought the opposite. Unburned fuel from 2 step going out exhaust and making a rich condition. My bracket car has a O2 reader and on 2 step it is rich and gets right by second gear shift. Yes on to big primary with no rods.

In a production car , when the engine misfires the O2 sensor reads lean , and then starts to add more fuel to correct . Most production calibrations will only allow so much correction , and once it reaches that limit , it sets a code . A misfire is similar to what a two step does only more controlled . I am surprised your engine reads rich when on the two step . Hopefully a few more folks will chime in with their experiences .

As far as running as big a jet with no rods , I agree , too big , but remember that this particular carb has the POE system , which adds even more fuel into the primaries at WOT . He might have to put a very small primary jet , or reinstall the power piston and primary rods .

[gsa612]

Originally Posted by ss3011

In a production car , when the engine misfires the O2 sensor reads lean , and then starts to add more fuel to correct . Most production calibrations will only allow so much correction , and once it reaches that limit , it sets a code . A misfire is similar to what a two step does only more controlled . I am surprised your engine reads rich when on the two step . Hopefully a few more folks will chime in with their experiences .

As far as running as big a jet with no rods , I agree , too big , but remember that this particular carb has the POE system , which adds even more fuel into the primaries at WOT . He might have to put a very small primary jet , or reinstall the power piston and primary rods .

^^^^ Read an article on one of the Burton firebirds.They claim to run a 61 pri.jet,it does not say if that's in Denver or...So say if you ran at sea level and went to a 63,that would be 11 steps leaner than the 74 that's in it now.You would think if it's that far off it would be just flat off the line.What does the car 60' 330' and ET. gsa612

[gearhead63]

when on the 2 step afr is 18-19 but afterreleasing the 2 step afr goes from 10.5-12 just before shifting to second gear. poe system blockt. best 60 foot 1.39 best et 10.69 in e/sa should change to 69 pri jet for the next race and but a gopro camera under the hood over the carburator.

[ss3011]

Originally Posted by gearhead63

when on the 2 step afr is 18-19 but afterreleasing the 2 step afr goes from 10.5-12 just before shifting to second gear. poe system blockt. best 60 foot 1.39 best et 10.69 in e/sa should change to 69 pri jet for the next race and but a gopro camera under the hood over the carburator.

You may not be too far off , your et and 60 ft is pretty darn good . Tweeking the primary jets will let you see what the combo wants . Also , my 455 HO wants around 40 degs of timing , what are you running ?

[gearhead63]

it likes 36-37 degrees best but we are using vp motorsport 109 are not allowed to use leaded fuel here in Europe. our goal is go 1.1sek under index to be a little faster than the other e/sa cars here.

[ss3011]

Originally Posted by gearhead63

it likes 36-37 degrees best but we are using vp motorsport 109 are not allowed to use leaded fuel here in Europe. our goal is go 1.1sek under index to be a little faster than the other e/sa cars here.

The VP 109 has plenty of octane for your engine , I would warn you that because that fuel has no anti corrosion additives it will rust the valve seats . You would need to fog WD-40 or some other spray lube into the intake after you are done racing for the weekend .

[gsa612]

What is the elevation of the track you run at ?. gsa612

[gearhead63]

the track were we ran 10.69 is 682 ft over sea level and we had 1700 ft of air.