WIDEBAND AIR/FUEL GUAGE

[CHESTNUTXE 7,300]

Hey has anyone put one of these air to fuel guages in their car ? great for tuning and jetting and WOT readings,im getting one,it really takes out the guess work.

[SirkWhyXF 1,533]

i wanted to change out for wide bands on my 5L but need to go full aftermarket ecu as the unichip won't cover it

[CHESTNUTXE 7,300]

im only just learning about this stuff,i run a carby and want to get it in fine tune.

[SirkWhyXF 1,533]

yeah i don't know squat really but from what i was reading into a while back they are a great tool for fine tuning.

[CHESTNUTXE 7,300]

14.7 is the magic number i think with 6 being as rich as a gasoline engine will operate,9 being black smoke and poor power,11.2 a bit rich,12.2 high performance,15-16 lean but good fuel miledge from what i was reading before.

[SirkWhyXF 1,533]

sounds like you've been doing your home work mate 

[CHESTNUTXE 7,300]

The last clevo i had i just couldnt get it right,now i no that i had way to big cam in it for street driving and it had almost no vaccum ,only 5 at idle and a new set of plugs were only lasting 100kms if that from new,i now no that the power valve was open most of the time and it was dumping so much fuel into the motor,i now have many tools and a vaccum guage ,to choose the right power valve,my 750 vac has a 6.5 in it and its spot on for a reading of 13 or more,the new clevo is going good no plug problem,just a tad rich in my view,front jets are 72 and once i get the air to fuel guage it will give me a more accurate reading,i have a set of 68 jet's which i might put in summer time because its dam hot here in QLD,but now its cooled off the clevo loves the colder air .

[gerg 10,871]

Shit 72 is a bit much... Are you running a double pumper? Sure sounds like it with that tune.

[CHESTNUTXE 7,300]

The carby place said nah stick with the 72 jets ,its a vacuum 750,

[slydog 7,873]

14.7 is the magic number i think with 6 being as rich as a gasoline engine will operate,9 being black smoke and poor power,11.2 a bit rich,12.2 high performance,15-16 lean but good fuel miledge from what i was reading before.

 

This is wrong. You tune to what the engine tells you it wants based on use not targeted figures. Doesn't matter what the figure is and TBH most innovate units will shit them selves pretty quick where as the AEM and such last forever.Better off actually getting it tuned on a dyno. 

[ando76 4,354]

14.7 is not really a 'magic' number. It's good for lighting up cat converters and under load for an extended period it's really good at burning holes in Pistons.

 

The graph below is a guide that may come in handy for you, but as Sly has pointed out there is no substitute for a good dyno tune. It's just way too dangerous to tune mid to upper speed air fuel mixes on the street.

 

Lean cruise and off idle, yep no problems with that, provided it's a 2 person operation. I strongly advise against road tuning by yourself, unless it's done where there are no other road users. None.

 

I've used the AEM units for years with meth and fuel and they are awesome. I know several people that have the innovate units and they all seem to fail.

 

Just remember AFR is just one piece of the tuning puzzle.

 

[SirkWhyXF 1,533]

This is wrong. You tune to what the engine tells you it wants based on use not targeted figures. Doesn't matter what the figure is and TBH most innovate units will shit them selves pretty quick where as the AEM and such last forever.Better off actually getting it tuned on a dyno. 

 

 

14.7 is not really a 'magic' number. It's good for lighting up cat converters and under load for an extended period it's really good at burning holes in Pistons.

 

The graph below is a guide that may come in handy for you, but as Sly has pointed out there is no substitute for a good dyno tune. It's just way too dangerous to tune mid to upper speed air fuel mixes on the street.

 

Lean cruise and off idle, yep no problems with that, provided it's a 2 person operation. I strongly advise against road tuning by yourself, unless it's done where there are no other road users. None.

 

I've used the AEM units for years with meth and fuel and they are awesome. I know several people that have the innovate units and they all seem to fail.

 

Just remember AFR is just one piece of the tuning puzzle.

 

 

 

Ok. As i stated earlier i don't know squat, but these guys do. I would be listening to them for sure.

[gerg 10,871]

If your carby has a power valve (and it does) and you're running close to stoichiometric at cruise, and you haven't played with bleeds or emulsion holes, there is no way you'll run that lean under load. The power valve generally adds about 10-12 jet sizes of fuel to the mix (on a vac sec).

 

Mechanical sec carbs run smaller power valve channels but bigger jets.

 

For a street engine, jet for cruise A/F and adjust WOT mixture by drilling power valve channel restrictors. You need jet drills for this.

 

If that's a bit more than what you're comfortable tackling, simple jet changes will get your WOT mixture correct but cruise will be rich. All Holleys, (even vac sec) are known to be this way, more so double pumpers, which are tuned for racing and need bigger jets for the equivalent size carby.

 

I'd take a punt on the 68s and see how you go. You'll know straight away if it's too lean.

[CHESTNUTXE 7,300]

from general observations id say its a bit rich at cold start and once warmed up pretty close,i had the carby built with no choke,i have 13 inches of vacuum in drive on the fmx,so by the holley guide video 6.5 power valve is spot on,i dont have any cats just a 3 inch single with big muffler,maybe thats why i smell a bit of fuel.

[PRO250 1,506]

I run one in the white car as you cant see the tune on LPG and being boosted its important that its it least close to right. It floats in the 14s driving low 12s when your into it and just bumps 11s at the top of the revs on max boost and 18s off the throttle. It will do this doing 40kmh as the throttle is so far shut it goes lean ive tried to step my rod to fix it but ive not solved it yet it just makes it hard to drive real slow and I never drive it that slow anyway it just shits me the guage flashing at me going  "Danger to manifold" LOL

NA fuel cars I tune by feel and althow not as reliable as it use to be looking at the plugs. a big clevo tells you want it wants and you just tune with your bum ear and foot I never needed one before racefuel or LPG or I did not have anything boosted for them you kind of need them althow I know a few that still don't run them they still do the bum ear foot method

while where talking about it my ute and grey car run in the low mid 70s range jetting in the fronts and low 80s in the back these are fair clevos with largish camshafts, what are your cam specs? maybe your jetting the carby up because its to big? my brown car use to do that tll I fitted a smaller carby I wanted to use my super duper 700 holley but ended up fitting a povo 600 to it it did not look shiny but it worked much better and used much less fuel. Just a idea as you may be having the same issue


 

[CHESTNUTXE 7,300]

everytime i mentioned to the carby shop that i want a 600 they said mate why do you want to use such a small carby on a 351 cleveland,its only a mild 2v engine,i can understand on a 302 a 600 would be fine.

[gerg 10,871]

Carby size depends on what you use your car for. A 600 could easily make over 300 hp on a 351, but it would not be to its full potential, probably 20 hp or so down on a 750. It would however be more drivable and suck less juice.

 

There's an article in car craft or hot rod (can't remember) that went from 390, 465, 600, 750, 850, 950 and even though their test engine a 383 from memory) was strangled by the 390, it still made amazing power for the size of the engine.

[CHESTNUTXE 7,300]

all this talk made me pull the plugs again to check cond and all but 1 were pretty good ,number 8 was a tad fuelie,i will probly put the 68's in for when it warms up and stick with the 72's in winter.

[LJDB 103]

Iv got a innovate MTX in mine and it plays up most of the time. The gauge sometimes gets stuck on the heater circuit or comes up with an error code after driving for 10-15 min. I haven't had mine for long but have used a octane booster that may have contributed to the sensor playing up. From my experience with it, Gerg is spot on with the jetting and PV restrictors. Mines a xflow with 570 street avenger and Im running 64 in prim and 58 in sec with wire in 4.5 PV restrictors. The 64 give a good cruise a/f but it was always rich at WOT that's why iv got the 58 in the sec and had to restrict the pv channels. Its still not perfect and im not 100% that the gauge is accurate. Power has definitely improved since leaning it out but il probably get it dyno'd at some stage and compare a/f ratios from the dyno and gauge. Also good to see if I got it close or not, Spark plugs are hard to read if using a octane booster or don't have any experience reading them. Online info can be contradicting at times much like everyone's opinions on jetting.  

[gerg 10,871]

Here it is... My memory failed me once more. It was a 383 but the magazine was Super Chevy

 

http://www.superchevy.com/how-to/148-0403-seven-holley-carbs-test/

 

Granted, the 390 was Nascar spec (for restricted class) but over 400 hp is nothing to sneeze at.

 

They reckon once they stepped up to a 600, there was little difference between them all the way to 1000 cfm.

[gerg 10,871]

Mines a xflow with 570 street avenger and Im running 64 in prim and 58 in sec with wire in 4.5 PV restrictors. The 64 give a good cruise a/f but it was always rich at WOT that's why iv got the 58 in the sec and had to restrict the pv channels.

 

I reckon your primary jetting is like that because the carby is a bit big for your engine (ie poor venturi signal = more jet needed). Have you thought about going lower in jet but drilling out the PVCRs?

[CHESTNUTXE 7,300]

i really wanted a 650 vac or a 670 street avenger,but have you guys seen how much they are ? like $550-700 for a newie,holley no's that 650 size is the most popular and keeps the price high,also the 465 is very expensive as well as 289-302 owners use this as there best bolt on,a new 750 3310 vac is quite cheap,and even cheaper is the reco one i got.

[LJDB 103]

My 570 came with the manifold. I've kinda given up playing with it as its going good atm. I want to try a 600dp on it as it loves the soft white vac spring and being manual with short diff gears would be better. Carb prices are high atm and ive seen EFI systems come down in price lately. Its only a matter of time before the technology become cheaper and easier to access. Check out FITech.com, Cheap from the US.

[PRO250 1,506]

i really wanted a 650 vac or a 670 street avenger,but have you guys seen how much they are ? like $550-700 for a newie,holley no's that 650 size is the most popular and keeps the price high,also the 465 is very expensive as well as 289-302 owners use this as there best bolt on,a new 750 3310 vac is quite cheap,and even cheaper is the reco one i got.

Shame you cant read minds i have a almost brand new 670 in the shed i bought it with a blown up 250 under it and fixed the engine sold it and kept the carby i also have a 770 street vac ill never use its almost brand new as well i just wanted the manifold under it i like holleys and have boxes of them you can pick up carbys from swap meets if you know what your looking at i got a 465 a little while ago for $20 it needs throttle shaft bushes but other then that its mint shane will rebush it for me for about $60 so it will be a cheap carby for a 250 to flip

 

Holley prices are nuts atm im looking at a new carby for my blown thing and its almost 1400, the carby on my ute was under 500 not long ago its now a 800 buck carby to buy. i seen a 650 hp pumper at the bendigo swap not long ago been converted to a gas throttle body it cost $100 cost 300ish to get metering plates bowls and pumps for it and now its whats on the ute just a hit on the summit website and it was completed why somone would use one as a gas TB i do not know but im happy it was less then half the cost of a new one and they look 500hp them carbys

[CHESTNUTXE 7,300]

I like the look of the hardcore grey ultra xp,but a bit pricey at around $900 to start off with,another holley that always looks good is the 780 GTHO type with the fuel inlet on the passenger side.A  remanufactured copy is around $750 or a genuine numbers one $2500.