Fixing Eddie

[Gary Lewis]

Hi.

Had to look up stoichiometric . Støkiometri in norwegian. Read a norwegian explanation to try to understand what it is. Succeded partly

I agree its to rich. Will try next bigger metering rod tomorrow. Timing is at 12 btdc.

And Bodø Glimt lost 0 -4 to Roma

Greetings Stein.

First, I was wrong. 14.4 is not right for stoichiometric. For pure gasoline it is roughly 14.7:1, but that varies by the type of gas and whether or not it has ethanol in it.

Second, the book Designing & Tuning High Performance Fuel Injection Systems has several charts that are informative. Here's the one on max fuel economy, and while it shows that max economy is at 15.4 it also says that "there is almost no difference in raw fuel economy between stoichiometry and leaner mixtures."

However, that maximizes NOx, as shown below. (Lambda is also soiciometric.)

And then there's max power.:

[StraightSix]

First, I was wrong. 14.4 is not right for stoichiometric. For pure gasoline it is roughly 14.7:1, but that varies by the type of gas and whether or not it has ethanol in it.

Second, the book Designing & Tuning High Performance Fuel Injection Systems has several charts that are informative. Here's the one on max fuel economy, and while it shows that max economy is at 15.4 it also says that "there is almost no difference in raw fuel economy between stoichiometry and leaner mixtures."

However, that maximizes NOx, as shown below. (Lambda is also soiciometric.)

And then there's max power.:

Stein,

Consider the possibility that the gasoline available to you may be different that what is commonly available in north America. I dont know if it is or not :/ most gasoline has a stoichiometric mixture in the range of 14.5-14.7 depending on contents like ethanol (alcohol) which is common here. Common US gasoline grades are 87, 89 and 93 octane. Eddies engine would have. Come from the factory set up for 87 octane.

Maybe all of this is obvious, if so I apologize.

I am aiming for 14-15 at highway speeds while cruising (45-65), and 12.5 or so at wide open throttle.

I have found a vacuum gage to be just as useful for tuning my carberator as the A/F gage.

To me, it sounds like you are a little rich across the board. You might even experience better driveability if you can get it a little leaner.

Good luck! I always enjoy reading your posts.

[ArdWrknTrk]

Stein,

Consider the possibility that the gasoline available to you may be different that what is commonly available in north America. I dont know if it is or not :/ most gasoline has a stoichiometric mixture in the range of 14.5-14.7 depending on contents like ethanol (alcohol) which is common here. Common US gasoline grades are 87, 89 and 93 octane. Eddies engine would have. Come from the factory set up for 87 octane.

Maybe all of this is obvious, if so I apologize.

I am aiming for 14-15 at highway speeds while cruising (45-65), and 12.5 or so at wide open throttle.

I have found a vacuum gage to be just as useful for tuning my carberator as the A/F gage.

To me, it sounds like you are a little rich across the board. You might even experience better driveability if you can get it a little leaner.

Good luck! I always enjoy reading your posts.

One difference is that in the US we use R+M/2

So octane ratings aren't the same in the rest of the world.

When the new corn subsidies go through and Americans start seeing 15% ethanol fuel I think I'm going to have to dial back my vacuum advance. I'm on the jagged edge as it is now.

[StraightSix]

One difference is that in the US we use R+M/2

So octane ratings aren't the same in the rest of the world.

When the new corn subsidies go through and Americans start seeing 15% ethanol fuel I think I'm going to have to dial back my vacuum advance. I'm on the jagged edge as it is now.

Gary - that information is very interesting. it looks like I should be aiming for 14.5 -15 for cruise, though realistically I havent been able to get my carb to meter fuel in a range that tight yet. I float from 13.8 to 15.5 (90% of the time between 14-14.5) depending on grade and moon phase (), and Im sure exact ambient conditions play a large factor as well. I suspect a more practical approach to carb tuning might be to do everything you can to generate stable intake air conditions (thermostatically controlled intake), then jet and adjust the carb such that you never go leaner that 15-15.5 at cruise.

[Gary Lewis]

Gary - that information is very interesting. it looks like I should be aiming for 14.5 -15 for cruise, though realistically I havent been able to get my carb to meter fuel in a range that tight yet. I float from 13.8 to 15.5 (90% of the time between 14-14.5) depending on grade and moon phase (), and Im sure exact ambient conditions play a large factor as well. I suspect a more practical approach to carb tuning might be to do everything you can to generate stable intake air conditions (thermostatically controlled intake), then jet and adjust the carb such that you never go leaner that 15-15.5 at cruise.

I agree with that approach - although I'd suggest testing your engine/meter combination to see how it works at certain reported AFR readings. I say that because I'm told that the AFR meters themselves vary, and that how far you put your O2 sensor from the cylinders varies the reading.

On Big Blue I saw 16:1 at times w/o adverse effects, although anything leaner caused the power output to wane and I had to give it more throttle which popped the rods up and provided a richer mix. But with a different meter on David/1986F150Six's truck I saw 17:1 w/o a noticeable loss or power or pinging. So the meter and the installation in the exhaust makes a difference and you should find out what your engine likes before setting a goal.

As for a tight range, I've never been able to get that to happen with a carb. The AFR varies by speed, RPM, load, etc. I gave up trying to adjust for anything between idle and 55 MPH as that seemed futile. And at 55 and up it varied from 14 to 16 depending on the speed, hill, wind, etc.

So I wound up picking a stretch of highway that was level and trying to get it to mid-14's on that stretch at 65 MPH with no wind. Then I'd see it go leaner as I gave it a bit of throttle to climb a hill - until the rods popped up and made it richer. But I'd see it go richer as the speed dropped off down towards 55 MPH. And even that description is much too tame as the AFR was very active.

Given all that you can see one of the reasons I'm going EFI. It'll have a target of something like 15:1 and should hold that until it is time for the power mode, wherein it should come in around 12:1. (Where's the fingers-crossed emoticon???)

[firefire]

I agree with that approach - although I'd suggest testing your engine/meter combination to see how it works at certain reported AFR readings. I say that because I'm told that the AFR meters themselves vary, and that how far you put your O2 sensor from the cylinders varies the reading.

On Big Blue I saw 16:1 at times w/o adverse effects, although anything leaner caused the power output to wane and I had to give it more throttle which popped the rods up and provided a richer mix. But with a different meter on David/1986F150Six's truck I saw 17:1 w/o a noticeable loss or power or pinging. So the meter and the installation in the exhaust makes a difference and you should find out what your engine likes before setting a goal.

As for a tight range, I've never been able to get that to happen with a carb. The AFR varies by speed, RPM, load, etc. I gave up trying to adjust for anything between idle and 55 MPH as that seemed futile. And at 55 and up it varied from 14 to 16 depending on the speed, hill, wind, etc.

So I wound up picking a stretch of highway that was level and trying to get it to mid-14's on that stretch at 65 MPH with no wind. Then I'd see it go leaner as I gave it a bit of throttle to climb a hill - until the rods popped up and made it richer. But I'd see it go richer as the speed dropped off down towards 55 MPH. And even that description is much too tame as the AFR was very active.

Given all that you can see one of the reasons I'm going EFI. It'll have a target of something like 15:1 and should hold that until it is time for the power mode, wherein it should come in around 12:1. (Where's the fingers-crossed emoticon???)

Hi all. Went for a test drive today. Now I had installed the two thickest metering rods.

At 40 mph cruising average reading 13,4. About the same at 50 mph. It is as Gary says the readings goes up and down constantly . Slightest shift in circumstances changes the reading. One observation like Garys. When increasing the throttle a little to keep the speed stable up a slight hill I got a stable reading for awhile of 13,5. Fuel consumption is down about 10%. To get it leaner I must change to smaller primary metering jets. They are in the same plastic box as the metering rods. The manual for the Street Demon is well written . In the manual they suggest 13,5:1 is good for steady state cruising. Any thoughts on that ?

Our gas is 95 with 5% ethanol or 98 without ethanol. I use both. Greetings Stein

[Gary Lewis]

Hi all. Went for a test drive today. Now I had installed the two thickest metering rods.

At 40 mph cruising average reading 13,4. About the same at 50 mph. It is as Gary says the readings goes up and down constantly . Slightest shift in circumstances changes the reading. One observation like Garys. When increasing the throttle a little to keep the speed stable up a slight hill I got a stable reading for awhile of 13,5. Fuel consumption is down about 10%. To get it leaner I must change to smaller primary metering jets. They are in the same plastic box as the metering rods. The manual for the Street Demon is well written . In the manual they suggest 13,5:1 is good for steady state cruising. Any thoughts on that ?

Our gas is 95 with 5% ethanol or 98 without ethanol. I use both. Greetings Stein

I think you are still too rich and are burning too much fuel. But you should check the AFR at a higher speed if you can since I've seen it lean out some above 50 MPH. If it stays around 13.5 I'd go ahead and change to smaller jets and see if you can get it to 14.5 to 15 at about 65.

However, I should ask what speeds you drive at? I've not driven out in the country, although I have in Stavanger, but from what I've seen the roads seemed fairly small with few straight sections. So do you get up to 65?

[firefire]

I think you are still too rich and are burning too much fuel. But you should check the AFR at a higher speed if you can since I've seen it lean out some above 50 MPH. If it stays around 13.5 I'd go ahead and change to smaller jets and see if you can get it to 14.5 to 15 at about 65.

However, I should ask what speeds you drive at? I've not driven out in the country, although I have in Stavanger, but from what I've seen the roads seemed fairly small with few straight sections. So do you get up to 65?

Hi. Around here max speed is 50 mph. 65 only on special occasions.

Stein.

[Gary Lewis]

Hi. Around here max speed is 50 mph. 65 only on special occasions.

Stein.

Then I'd aim for 14.5 - 15 at 50 MPH.

[firefire]

Then I'd aim for 14.5 - 15 at 50 MPH.

Hi.

Took Eddie out this morning for a test drive. AFR readings are hovering around 13,3 at all speeds from 20 - 65 mph.

At idle 13,3

Engine 100% warmed up.

When accelerating normally afr starts at 11,4.

So the saga goes on🙂

Greetings Stein