Check my carb tune please?

[JerseyJoe]

Just a suggestion, however, on seating those IFR jets - I noticed mine (like yours) sat nearly flush with the surface of the metering block. I tapped the threads a little deeper to recess the face of the jet relative to the face of the metering block. Might not matter, I dunno, but I was concerned about the gasket swelling a bit over time and obstructing flow into the jet.

Yes, I'm thinking if it obstructs that passage it might cause a lean condition but I'll be keeping that in mind. I'll probably get 1/8" brass screws to make sure. I used 3/16".

 

[Canadian1968]

Not necessarily......the transition from idle to main fuel feed is dependent on the POSITION of the throttle plate's leading edge in relation to the transfer slots in the throttle bore.....its not RPM dependent.
BOB RENTON

For this.comment I was thinking of my own engine. If I am at 1500 rpm I am not on the idle circuit if I was actually driving the car. Or if I had the car idling qnd turned the idle up to 1500rpm I would for sure be Tipping or transitioning into the main circuit. As you stated the blade position is just open to much not be pulling on the main circuit.

I do realize his motor is much different than mine and his carb as well. I just found hard to belive the carb is still solely running on the idle.circuit at 1500rpm. But maybe it is .

 

[hunt2elk]

For this.comment I was thinking of my own engine. If I am at 1500 rpm I am not on the idle circuit if I was actually driving the car. Or if I had the car idling qnd turned the idle up to 1500rpm I would for sure be Tipping or transitioning into the main circuit. As you stated the blade position is just open to much not be pulling on the main circuit.

I do realize his motor is much different than mine and his carb as well. I just found hard to belive the carb is still solely running on the idle.circuit at 1500rpm. But maybe it is .

My Quick Fuel Carbs don't transition to the main jets until 2300-2400 rpm.

 

[Canadian1968]

Curious as to how you know this ?

 

[RJRENTON]

For this.comment I was thinking of my own engine. If I am at 1500 rpm I am not on the idle circuit if I was actually driving the car. Or if I had the car idling qnd turned the idle up to 1500rpm I would for sure be Tipping or transitioning into the main circuit. As you stated the blade position is just open to much not be pulling on the main circuit.

I do realize his motor is much different than mine and his carb as well. I just found hard to belive the carb is still solely running on the idle.circuit at 1500rpm. But maybe it is .

The main or booster venturii assemblies begin feeding fuel based on air VELOCITY thru the bores to create enough differrntial pressure that they begin to feed fuel. Its a gradual happening....the idle/transfer system tapers off while the main fuel feed gradually tapers on......based on velocity and atmospheric pressure.
BOB RENTON

 

[Canadian1968]

The main or booster venturii assemblies begin feeding fuel based on air VELOCITY thru the bores to create enough differrntial pressure that they begin to feed fuel. Its a gradual happening....the idle/transfer system tapers off while the main fuel feed gradually tapers on......based on velocity and atmospheric pressure.
BOB RENTON

Yes exactly. Explain it how you want . The more you open the throttle blades , the more the air threw the carb. The idea is to keep that increase of air volume in par with the amount of fuel. The boosters don't just instantly kick in like you said. That's where the accelerator pump comes in for that quick shot to cover that overlap of the transition until air speed picks up . I had a similar problem to the OP ,but my carb does not have adjustable IFR or any of the other fine tuning capabilities of the new crabs . I was able to fix my problem with accelerator pump cam and correct jetting.

 

[hunt2elk]

Curious as to how you know this ?

If you are asking me how I know? By watching my A/F meter.

 

[JerseyJoe]

Curious as to how you know this ?

Watching the meter, I could see the ratio go from fat to normal above 2000 rpm. That lead me to focusing on the idle circuit.

 

[RJRENTON]

Not exactly sure of the fascination with A/F readings especially since there are no repeatable data collection points.....barometric pressure, temperature, road load, RPM, MPH, throttle position or MAP (Manifold Absolute Pressure), air density and volume, pick up point of probe supplying oxygen info, on or two O2 probes (one per bank of cylinders). All these are discrete variables and overall, that can and do change, almost instantaneously.....so, for example, at 50 mph the A/F ratio is xx.xx is good; at 55 mph the A/F ratio is xx.xy or xy.yy its bad.....and who determins what is good or bad, but how can these variable conditions be repeated to be of any tuning value. To me, it sounds like a "one upsmanship" contest.,..my A/F meter is better than your A/F meter especially on a car with a carburetor. Please elaborate.....
BOB RENTON

 

[steve340]

Assuming the A/F meter is correctly installed, calibrated and working correctly.
Most that I have seen compensate for temperature change and some you can collect the data to view on a computer.
I do agree they do jump around - a bit of "averaging" is required. That is the nature of tuning a carb anyway to me.
However they do allow a novice or experienced tuner who has a few brains to do a very good job of dialling in the carb.
The meter also makes the job far quicker and IMO more accurate. It allows you to see the circuits like plug reading never could.
I wouldn't be without one these days, used correctly they eliminate a lot of guesswork.

 

[Canadian1968]

Not exactly sure of the fascination with A/F readings especially since there are no repeatable data collection points.....barometric pressure, temperature, road load, RPM, MPH, throttle position or MAP (Manifold Absolute Pressure), air density and volume, pick up point of probe supplying oxygen info, on or two O2 probes (one per bank of cylinders). All these are discrete variables and overall, that can and do change, almost instantaneously.....so, for example, at 50 mph the A/F ratio is xx.xx is good; at 55 mph the A/F ratio is xx.xy or xy.yy its bad.....and who determins what is good or bad, but how can these variable conditions be repeated to be of any tuning value. To me, it sounds like a "one upsmanship" contest.,..my A/F meter is better than your A/F meter especially on a car with a carburetor. Please elaborate.....
BOB RENTON

Having a wideband gauge on my car as well ,I can tell you it absolutely is a great tuning aid. Instant feed back. It takes the guess work out of wondering if it's a lean condition or rich. You can see how motor is reacting at all parts of operation. Is it exact ? Of course not especially if your only reading from one bank. But it does give your a VERY good idea what is going on. Using it in conjunction with a vacuum gauge and you can arm your self with a lot of great information.

Your example of 50 and 55 mph is vague obviously a carbed engine does not have the on-the-fly adjustments of modern computerized fuel system but the more info you have the better chance you have at solving your problem.

I've talked 2 of my friend into installing A/F gauges and the amount of progress we made on the 2 cars with the extra information is undeniable

 

[HEMI-ITIS]

I would call Dom and get the tune info from him!!

 

[JerseyJoe]

Not exactly sure of the fascination with A/F readings especially since there are no repeatable data collection points.....barometric pressure, temperature, road load, RPM, MPH, throttle position or MAP (Manifold Absolute Pressure), air density and volume, pick up point of probe supplying oxygen info, on or two O2 probes (one per bank of cylinders). All these are discrete variables and overall, that can and do change, almost instantaneously.....so, for example, at 50 mph the A/F ratio is xx.xx is good; at 55 mph the A/F ratio is xx.xy or xy.yy its bad.....and who determins what is good or bad, but how can these variable conditions be repeated to be of any tuning value. To me, it sounds like a "one upsmanship" contest.,..my A/F meter is better than your A/F meter especially on a car with a carburetor. Please elaborate.....
BOB RENTON

I was trying to achieve the bragging rights of "I don't foul my plugs because my idle mixture was too rich".

 

[RJRENTON]

Having a wideband gauge on my car as well ,I can tell you it absolutely is a great tuning aid. Instant feed back. It takes the guess work out of wondering if it's a lean condition or rich. You can see how motor is reacting at all parts of operation. Is it exact ? Of course not especially if your only reading from one bank. But it does give your a VERY good idea what is going on. Using it in conjunction with a vacuum gauge and you can arm your self with a lot of great information.

Your example of 50 and 55 mph is vague obviously a carbed engine does not have the on-the-fly adjustments of modern computerized fuel system but the more info you have the better chance you have at solving your problem.

I've talked 2 of my friend into installing A/F gauges and the amount of progress we made on the 2 cars with the extra information is undeniable

BUT.....HOW DO YOU DUPLICATE THE EXACT SAME CONDITIONS THAT YOU WERE TRYING TO CORRECT OR IMPROVE UPON? If the adjusted calibration points cannot be realised or duplicated, what's the point? A reading is taken, corrections (?) made by what ever means.....jets, metering rods and/or air bleeds, unless the exact data collection points are duplicated, the results obtained are only an approximation. To that end , it seems like exercise in futility. Where do the reference A/F values come from? Is it the stoiciometeric value of complete combustion plus a percentage of excess air (?). Because the BTU value of the fuel is changing based on brand of fuel and data logging is not performed to develop history, the A/F readings are not really viable but sort of nice to know. Do you have data to support your premise?......just curious....I'm well,aware how modern processor controlled systems operate as they use a combination of feed back and feed forward design.......
BOB RENTON

 

[Canadian1968]

PULLING OUT THE CAPS LOCK LOOK OUT ! How do you duplicate the EXACT same conditions with any car ? You don't, unless maybe your in a dyno room.

Do I have data ? Although my wideband does have the ability to data log I have not used it. Or are talking about the countless bits of information on NA engine and when there are performing at their best, for either power or economy ?
BUT I do know when I drive my car with the current setup. If the air is temp is between 20-28*c my car will cruise at 14.3-13.8 . During accelerations and wot I hit around 12.5 to 13. There are fluctuations that you cannot control, as we already discussed. I already said the gauge is NOT EXACT, so I'm confused on why your arguing that you cannot duplicate exact readings.

Its already been said the Gauge is a tuning AID not all mighty one thing tells all.

 

[RJRENTON]

PULLING OUT THE CAPS LOCK LOOK OUT ! How do you duplicate the EXACT same conditions with any car ? You don't, unless maybe your in a dyno room.

Do I have data ? Although my wideband does have the ability to data log I have not used it. Or are talking about the countless bits of information on NA engine and when there are performing at their best, for either power or economy ?
BUT I do know when I drive my car with the current setup. If the air is temp is between 20-28*c my car will cruise at 14.3-13.8 . During accelerations and wot I hit around 12.5 to 13. There are fluctuations that you cannot control, as we already discussed. I already said the gauge is NOT EXACT, so I'm confused on why your arguing that you cannot duplicate exact readings.

Its already been said the Gauge is a tuning AID not all mighty one thing tells all.

It depends on one's view point.....personally, knowing the difference between 14.3 and 13.8 is useless....what purpose does it serve? Are these values related to the stoichiometric value of perfect combustion? Do you know what stoichiometric combustion is? Unless the A/F readings are related to something, it's like saying: "how high is up?" If you are going to the trouble and expense of purchasing and installing this equipment, and not utilizing its full capability, what purpose does it serve, other than to say: "my A/F readings show....." or to "impress" your other car friends? If you're satisfied....great....personally, I don't really care what any particular A/F reading is compared to any other reading...I don't race the car or have any intention to do so....to each his own volition .....
BOB RENTON

 

[steve340]

The reading of 14 on the gauge means 14 parts of oxygen to 1 part of fuel.
Hence a gauge reading of 12 is richer than a reading of 14.7 - I do know what stoichiometric is.
The readings you would need to get on your gauge at sea level are well publicised in the instructions that would come with a quality A/F meter.

 

[RemCharger]

There are fluctuations that you cannot control, as we already discussed. I already said the gauge is NOT EXACT, so I'm confused on why your arguing that you cannot duplicate exact readings.

Some dudes enjoy the game of arguments, that's all.

It takes all different kinds on a forum board lol.

Check out the one guy that always says everyone's wrong. Which would infer, he is always right. It's hilarious

 

[Canadian1968]

It depends on one's view point.....personally, knowing the difference between 14.3 and 13.8 is useless....what purpose does it serve? Are these values related to the stoichiometric value of perfect combustion? Do you know what stoichiometric combustion is? Unless the A/F readings are related to something, it's like saying: "how high is up?" If you are going to the trouble and expense of purchasing and installing this equipment, and not utilizing its full capability, what purpose does it serve, other than to say: "my A/F readings show....." or to "impress" your other car friends? If you're satisfied....great....personally, I don't really care what any particular A/F reading is compared to any other reading...I don't race the car or have any intention to do so....to each his own volition .....
BOB RENTON

Why do you always challenge people on their knowledge ? Yes I know what stoichiometric combustion is. Yes I know what the numbers on an A/F gauge mean? what im not going to do is write out some long winded explanation like you would.

Sorry to burst your bubble where the world revolves around you and you think your the smartest person in the room.

Myself and A LOT of other people know what the numbers on an A/F gauge mean . This is apparently a surprise to you ?

What most people don't do is try and spew a ton of over technical descriptions that is not needed to answer half the questions on this board. Yet you do this on a constant basis . I can only think this must make your feel superior some how ? This is not the first time you have challenged me on some of my post. If that helps you sleep at night then so be it.

what is the difference between 14.3 and 13.8 at cruise ???? Not to much ,that is the point. The car is running where i want it to be, and where it likes to be. Now if i am cruise and I feel the car is struggling, or its acting odd, I can look at my gauge, its now reading 15.5 ? Hmmm thats weird, is it spiking to 15.5 or is it constant,??? I can read this instantly and start to problem solve the situation.

Doesn't mean anything unless the ratio is related to something ? How about throttle position for starters ? I would say that's pretty damn consistent.?

I do not know 1 single person that brags about their A/F ratio? What is there to brag about?

Its a tool to help your car run the best that it can. Thats not a persons "view point " why would you dismiss someone trying to improve their vehilce.??

You don't need to be a drag racer to use an A/F gauge . ( another major point you seem to fail to grasp ) NOT ONCE has drag racing been the topic in this thread.

You don't care what your A/F reading is ??? That is an outright LIE . You are basically saying you don't care how your car runs then. Its bogs off idle, it back fires , my motor sounds like it has a bunch of marbles in it.......... MEH doesn't matter becuase I am to good for all this air fuel non sense??? WTF

If anything your really making your self look like the one that doesn't understand how USEFUL an A/F gauge acutally is .

to each his volition........

 

[BSB67]

Check out the one guy that always says everyone's wrong. Which would infer, he is always right. It's hilarious

Wait. You talking about me?