a/f meter in car using 110 octane

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swifter

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Anyone have one mounted in there car?? Seems to be a argument about diff. Octane levels and a/f readings, we have a dual sensor fast meter and at wot were running 12 to 1 ratios with 110 and 34 degrees of timing. Thanks steve
 
Not sure about the effect of octane on AFR-values.
For a stripcar I would tune and Trial&Error for best MPH and use the recorded AFR measurements to be able to repeat that tune for different tracks and weatherconditions.
 
Octane should have no effect on AF ratio, but will effect total timing and therefore power potential. This assumes your compression is high enough to require that octane rating.

If your 110 is leaded (blue Avgas) the lead may shorten the life of the oxygen sensor.
 
swifter said:
Anyone have one mounted in there car?? Seems to be a argument about diff. Octane levels and a/f readings, we have a dual sensor fast meter and at wot were running 12 to 1 ratios with 110 and 34 degrees of timing. Thanks steve
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I run one installed in the car and it runs about 12.5 average out on the road.
When I get into the secondaries it drops to 10.5 average, so I'm going to drop a size on the primaries and see where it is then.
Might have to drop a size on the secondaries after that if it isn't closer at wot.

Sound like you could drop a size on the secondaries, as long as the low and part throttle A/F is pretty good.
 
12.5 on Average? How often per week do you clear the coal lumps of the sparkplugs with those kinda AFR's?
 
So you gonna donate something useful big block??? Please do since it seems you have a answer and could help.motor is 14 to 1 so yes I need to run 110, so big block your saying 12 to 1 is rich???? Like you did at one time you had to start somewhere like we are doing, this is our first rodeo and looking for help if you cant then go away but dont be a smart *** it doesnt help anyone-thanks steve
 
Trailbeast -there is no mid throttle its idling or full throttle -drag car hence posted in the racers forum.thank steve
 
12.5 is in a decent range for WOT.

For cruise, 12.5, that's rich which I believe the coal lumps was referred. If the engine is in the 10's at WOT, it needs about 4 sizes or more smaller on both ends is my guess for WOT. Unless it's a turbo/blower car, then it's not far off on gasoline.

Swifter, start out by pulling 2 jet sizes front and rear and see what happens with MPH. Picks up, you went the correct direction. 12.0 is usually rich side for N/A engines. Don't jet to a number, let the MPH tell you if you are headed the correct direction.
 
Didn't mean to hijack Swifters thread with my own info, and didn't notice racers forum.
Just trying to get a relationship between the A/F readings and jet sizes, and saw the question about anyone running an A/F mounted in the car and thought sharing the info might be relevant.
 
Trailbeast, a better A/F ratio for cruise is 13.5 or higher. I like to be in the 14.0-14.5 range. WOT 12.0-13.0. Usually on ethanol infused pump gas, I've seen 12.3-12.5 ranges to be good. Without getting some MPH readings, it's just a guess. That's definitely a safe range.

Depending on the carb, the changes that need to be made are different. If the main circuit isn't active, main jet changes won't alter your cruise A/F. Air bleeds, emulsions, IFR on holleys can make a big change in cruise a/f. Ede/carter, rods, springs, etc.

Maybe start a fresh thread. :cheers:
 
Swifter,
I see there's a misunderstanding here so I won't feel attacked, but I was replying to Trailbeast last post 'cause he mentioned 12 to 1 with average use. Not WOT.
THAT is way to rich.

During WOT 12's are ok I guess.
 
crackedback said:
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Swifter, start out by pulling 2 jet sizes front and rear and see what happens with MPH. Picks up, you went the correct direction. 12.0 is usually rich side for N/A engines. Don't jet to a number, let the MPH tell you if you are headed the correct direction.
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Crackedback is spot on here ^^^^^. Use all the tools you have to get it tuned, jet to maximum MPH, read the plugs, and check the AFR gauge to see if it matches what the plugs and MPH are telling you (it should be close). Once you know what you car likes, you will have the data to tune it down the road by just looking at the AFR gauge....but I would still jet to the best MPH, that method has never failed me. My AFR gauge is still pretty new to me and it is still gaining my trust, lol.

I don't think the octane of the fuel would have much affect on the AFR. The O2 sensor is just reading how much oxygen is in the exhaust gases as far as I understand it. I have a AF meter in my car as well, but since I'm on e85 the optimum AF ratios are different.
 
No chip on my shoulder looking for help and misunderstood big block , im doing this on my phone so I can't see all the posts at once so I thought he was responding to me !!!!! Ok SORRY BIG BLOCK-i have enough problem using this damm smart phone much less a computer! !!! Thanks Steve
 
Its all good trilbeast we all needed to start somewhere and ALL are continuing to learn-steve
 
Thanks Fly I follow all of your posts-you have the experience to help a lot of us wanna be first timers.were trying to get the traction issues dealt with so we can test and tune tues and then thurs. Its off to kil kare for monster mopar -steve
 
Thanks crack we will head in that direction -and report back---steve
 
Just a thought. If 110 is leaded, you sniffer in the pipe will get clogged very quickly "I thnk". I thought that A/F meters don't like leaded gas. Anyone know for sure?
 
Its 110 Vp I dont think its leaded??? But I've been wrong A LOT
 
And we just got the a/r meter back from fast for calibration so I think its spot on
 
Ted Carlson said:
Just a thought. If 110 is leaded, you sniffer in the pipe will get clogged very quickly "I thnk". I thought that A/F meters don't like leaded gas. Anyone know for sure?
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That is correct and it says that in the instructions for the guages.
Mine did anyway.
It says if you run leaded fuel to use the guage for tuning only and then remove the sensor and cap the bung.
 
THanks Fly-We will have to watch the sensors and how long they last,I don't think it will be to bad cause we run straight headers so it will be a good test for the fast product and sensors--Steve
 
Leaded fuel and O2's are not compatible. Use it to get it close then get it out. They dont last long, just the way it is and there is nothing you can do to avoid it as far as I know.
 
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