Asking for help Interpreting AFR readings from new Weber 32/36

[matrophy]

Maybe we can start over? I realize that my original post was a little hard to interpret and this thread is straying pretty far..

 

I have attached 2 charts from my AFR gauge (Lambda actually) showing the AFR at idle and the AFR while shifting through the gears and cruising at 60 mph.

I have sluggish response when accelerating and while upshifting or merging (my Hitachi was peppier) and am running lean while cruising.

 

I have 2 questions

 

1) When I set the idle mixture, should I tweak the mixture to get the best AFR even if that is not the best lean best idle? It seems like the engine wants to run at lean best idle richer at around 12.5 (Lambda=0.85). A slight tweak of the screw affects the idle's smoothness a little bit but gets to around 14.0 (Lambda=0.95).

The idle chart is after adjusting the idle mixture a little bit to get to stoich.

 

2) Given the performance shown on the cruising chart, should I fatten up my main jets and should I do both at the same time and any recommendation for how much?

2a) As I understand it, I wouldn't need to do anything to the air correctors unless I have issues at WOT once the mid range is sorted out.

 

 

 

Thanks,

Colin

[Madkaw]

My response will not be any different. These carbs need to be tuned for your engine-but that's the good part about a Weber , it is tunable. I found that straight out of the box the carb ran lean in the areas you describe. To counter act this most will open up the mixture screw beyond the recommended 2 turns out. This gives you a pig rich idle and doesn't help with lean areas you are addressing -at least not enough to help. Then you read about folks going with the 38/38 for more performance , but I don't think these engines need this. Let's face it -it's a 80's truck that's pretty slow for todays standards. After jetting my carb it was a different engine. I still have to lay into the throttle and highway speeds will always be a challenge for these trucks . I have 3.90 gears and 30" tires, so I'm at a deficit already, but have no issues with keeping up with traffic except trying to make this truck merge onto a 70 mph highway . Around town and rural highways it scoots well. 

 

What diff ratios are you running? Do you have stock tire sizes?    

[Jitenshakun]

Sluggish acceleration on a Weber has more to do with emulsion tubes and the booster/pump jet. Change those out before worryimg about idles or mains. 

 

Bad constant speed is idle and bad once you are really on the gas is the mains. 

 

It sounds like you issue is in the transition between circuits. 

[Madkaw]

5 hours ago, Jitenshakun said:

Sluggish acceleration on a Weber has more to do with emulsion tubes and the booster/pump jet. Change those out before worryimg about idles or mains. 

 

Bad constant speed is idle and bad once you are really on the gas is the mains. 

 

It sounds like you issue is in the transition between circuits. 

Agree. The redline kit came with a 55 double pump jet which I installed and it really helped for initial tip in , but it only lasts so long . 
 

“really on the gas” is subjective . I think if you try and drive it like your DD commuter in the city , you will be on the gas a lot , so the mains need to be there . 

I will add that I am going to play with the emulsion tubes this week . Maybe shoot for a more responsive primary circuit . I am currently one turn out with the 60 tube- maybe put the 65 in there and turn in 1/8 or so and go for a spin . Maybe I’ll find more POWER!

 

I tried the 65 emulsion tube and its a big NO. At least for my truck it don't work. More fuel-but too much -which made it more sluggish. 

 

Edited June 30, 2021 by Madkaw
because I can

[Charlie69]

It amazes me that you are experiences sluggish feeling from a Weber.  Every Weber new or used I have installed over the last 40 + years has been a power increase to the vehicle.

 

Your description of your engine condition sounds good.  I am beginning to thik that your Weber is factory defective.  I have nevere had one that was factory defective but that does not mean it can't happen.

 

Man I am at a loss here trying to help you.

[datzenmike]

Sluggish is very subjective. Maybe it's working just fine but you expect more.

[Logical1]

I just slapped a new weber out of the box on a fairly fresh rebuilt z24 84' 2wd 720 and it freaking hauls ass! This was in the Seattle area so basically sea level. But I am with charlie even the used webers I have used were a vast improvement. Sounds like something is wonky with your carb.

[matrophy]

On 6/22/2021 at 1:38 PM, datzenmike said:

Octane is a resistance to self or auto ignition. You can compress it more or increase the timing advance to increase efficiency. There's no advantage to using it if you have a lower compression engine.

 

What timing do you have right now? Can you increase it without it pinging?

Mike, I advanced the timing to 10 degrees BTDC and it seems to make the idle much smoother. I am noticing what sounds like a knock at idle. I thought it was valve adjustment and I'm going to look at the valves tomorrow but I thought maybe it's knocking from the advanced timing. Is it possible that it might knock at idle with timing advanced?

[datzenmike]

All engines since the late '60s are running retarded timing at idle. This is strictly an emissions reducing thing.  This is a Z24? It should be 3 degrees. So advancing the timing will make the engine more efficient and capture more energy and the idle will smooth out and go up. The problem is that the distributor would run way to advanced as it revs up. It's just the way it is. 10 when it should be 3 is way to much The Z24 is very tolerant of too much advance but 10 is too high. 

 

Are both the intake and exhaust side plugs firing?? Both firing then 3 degrees (or up to 5). If only one side then the engine will respond well to more advance. Get both side firing if it isn't already.

 

A loose valve is more of a tapping sound almost a clicking. 

[matrophy]

24 minutes ago, datzenmike said:

All engines since the late '60s are running retarded timing at idle. This is strictly an emissions reducing thing.  This is a Z24? It should be 3 degrees. So advancing the timing will make the engine more efficient and capture more energy and the idle will smooth out and go up. The problem is that the distributor would run way to advanced as it revs up. It's just the way it is. 10 when it should be 3 is way to much The Z24 is very tolerant of too much advance but 10 is too high. 

 

Are both the intake and exhaust side plugs firing?? Both firing then 3 degrees (or up to 5). If only one side then the engine will respond well to more advance. Get both side firing if it isn't already.

 

A loose valve is more of a tapping sound almost a clicking. 

The 10 degrees advance is Redline's generic recommendation for Weber carbs so I tried it.

 

I am only thinking that the noise might be related to the timing because the advance is the last thing I did before I started hearing a rhythmic knock. I know this z24 always has some valve noise and maybe I'm just freaking myself out and it's the valves although I checked them a week ago and found 1 exhaust valve that was a little tight. Maybe it loosened up - I'm hoping it's valves and not something else.

 

Both sides are firing. If returning the timing to 3 degrees doesn't stop the noise, I'm going to check the valves cold then hot. If that fails, I was going to pull one sparkplug wire at a time to see if I can figure out what cylinder the noise is coming from. As far as I know, if the noise stops it's pistons or below and if it doesn't it's probably valves - correct? I'm wondering if I should unhook the exhaust coil when I do that so the exhaust valves don't fire. 

 

I can't really tell where the noise is coming from. I used a stethoscope on the block and the loudest ticking/knocking was around the water pump. Would a water pump going out make a noise? 

[Jitenshakun]

48 minutes ago, datzenmike said:

All engines since the late '60s are running retarded timing at idle. This is strictly an emissions reducing thing.  This is a Z24? It should be 3 degrees. So advancing the timing will make the engine more efficient and capture more energy and the idle will smooth out and go up. The problem is that the distributor would run way to advanced as it revs up. It's just the way it is. 10 when it should be 3 is way to much The Z24 is very tolerant of too much advance but 10 is too high. 

 

Are both the intake and exhaust side plugs firing?? Both firing then 3 degrees (or up to 5). If only one side then the engine will respond well to more advance. Get both side firing if it isn't already.

 

A loose valve is more of a tapping sound almost a clicking. 

I noticed that right at 3deg there's a diesling kind of sound changing gears and a bit of a rough idle on my Z24. At about 4.5deg it's much happier. It was at 10deg when I got it, so I'm still well below where it was. 

 

Is a bit more advance ok long term? 

 

I agree 10deg is too much. 

[datzenmike]

The Z series is very forgiving of too much advance. This is probably the hemi combustion chamber and the low compression. Advancing too much will likely just reduce power. Factory says 3 degrees plus or minus 2 degrees. So yes you can go as high as 5 degrees depending on what gas you run.

 

 

 

 

The valves don't 'fire' the spark plugs do. The Z24 has two plugs and this allows the fuel and air to burn faster in a shorter time. Because it takes less time to burn you can start the fire later (3 degrees) rather than earlier. (10 degrees) This why I asked if both exhaust and intake plugs were firing. If you were only firing one plug then you definitely would have to advance the timing and start it sooner because it would take longer to burn.

 

You will need to pull both plugs per cylinder to see if there is any change. I'm not sure this will tell you anything.

 

A bad rod bearing tends to knock louder under load and be quieter when you let off.

 

A badly adjusted rocker arm clicks the same all the time and speeds up and down with the engine.

 

 

[Jitenshakun]

Ah, I totally ignored the +/- 2 deg that's right on the sticker. 

 

I'm firing all spark plugs but definitely lean, and that's off a sub-optimal spark plug colour read. 

 

AFR goes on soon and I'll tune from there. 

[Charlie69]

I have found on all my Datsun and Nissan trucks I have owned that if I drive them like I stole them they seam to run smoother.  I prefer cornering on 2 wheels! LOL

[matrophy]

On 7/1/2021 at 9:01 AM, Charlie69 said:

It amazes me that you are experiences sluggish feeling from a Weber.  Every Weber new or used I have installed over the last 40 + years has been a power increase to the vehicle.

 

Your description of your engine condition sounds good.  I am beginning to thik that your Weber is factory defective.  I have nevere had one that was factory defective but that does not mean it can't happen.

 

Man I am at a loss here trying to help you.

I appreciate the help Charlie. I went up a size on main jets and at least while increasing the rpms above 2000, the afr readings were richer. I was pulling out of the driveway to take a test drive and the ALT light came on bright red. I pulled back in and after going over the alternator, I ended up having to order one. Once it comes in I’ll take her for a drive and see if the bigger main jets made it peppier.

[Charlie69]

My Weber I bought from Pierce Manifolds in 2011 for my then new to me 86 king cab 2wd ran in Northern Nevada just fine out of the box.  Battle Mountain Nevada is 4500' elevation.  When I drove it home to Phoenix AZ I figured I would have to re-jet it as Phoenix AZ is 1086' elevation. But I have been home since 2012 and have not done anything to the carb but clean and lube it and clean the air cleaner.

 

All the Webers over the year new and used I have done minimal maintenance to and all ran better than the stock carb.

 

I have not run the carb I bought from Carbs Unlimited, and after your experience am wondering if I will have similar problems with mine.

 

I am wondering if maybe Carbs unlimited are stripping the actual Weber carbs for the OEM parts and then installing Chinese knock off parts and selling them.

 

I have no way to verify this but just curious.

 

I will install the carbs unlimited Weber on my 86 and see what it does.  I will report back.

Edited July 7, 2021 by Charlie69

[matrophy]

2 minutes ago, Charlie69 said:

My Weber I bought from Pierce Manifolds in 2011 for my then new to me 86 king cab 2wd Ran in northern Nevada just fine out of the box.  Battle Mountain Nevada is 4500' elevation.  When I drove it home to Phoenix AZ I figured I would have to re-jet it as Phoenix AZ is 1086' elevation. But I have been home since 2012 and have not done anything to the carb but clean and lube it and clean the air cleaner.

 

All the Webers over the year new and used I have done minimal maintenance to and all ran better than the stock carb.

 

I have not run the carb I bought from Carbs Unlimited, and after your experience am wondering if I will have similar problems with mine.

 

I am wondering if maybe Carbs unlimited are stripping the actual Weber carbs for the OEM parts and then installing Chinese knock off parts and selling them.

 

I have no way to verify this but just curious.

 

I will install the carbs unlimited Weber on my 86 and see what it does.  I will report back.

I know the throttle valves they sold me were definitely used. They don’t answer the phone so I couldn’t get any help from them

[Charlie69]

They hung up on me.

[matrophy]

Thanks for everyone's help! I finally got the Weber from hell running pretty close to what I expected. Accelerating through the gears pulls well and AFR levels are real good now at idle and cruise. I got up to 70 mph today without even trying. I ended up with the 60 idle jet and advanced the timing to 5BTDC. I ended up going from 140/140 on the main jets to 150/150. It's running a little rich according to the AFR gauge so I'm going to run a few tanks of Premium E90 and see how the mileage is. I might go with 145/145 or 145/140 but I'm not going to play with it too much if the gas mileage is OK. I learned a lot about how these things work. I now have to remind myself not to put my foot in it so much but it is pretty fun taking off from a stoplight now. I do have a problem with the fast idle but if I can't figure it out - there's not a lot of info online about how to set it -  I might start another thread.

[Charlie69]

Nice work and determination.  I hope when I go to run the Carbs Unlimited Weber on my 66 520 with the L20B automatic trans that it goes better than this one did for you.

 

The box I got my Weber in from Pierce Manifolds for my  86 720 king cab has K646 sticker on the box.

 

Carbs Unlimited provides free shipping on my purchase but the carb came in a cut down generic box.  I would have rather padi for shipping and recieved the carb i the original box with the original packing.  So I have no idea what Redline # kit I recieved.

[matrophy]

58 minutes ago, Charlie69 said:

Nice work and determination.  I hope when I go to run the Carbs Unlimited Weber on my 66 520 with the L20B automatic trans that it goes better than this one did for you.

 

The box I got my Weber in from Pierce Manifolds for my  86 720 king cab has K646 sticker on the box.

 

Carbs Unlimited provides free shipping on my purchase but the carb came in a cut down generic box.  I would have rather padi for shipping and recieved the carb i the original box with the original packing.  So I have no idea what Redline # kit I recieved.

I have quite a few jets left over if you need any

[Charlie69]

Thank you, I will see what happens when I go to use that carb.

[Madkaw]

22 hours ago, matrophy said:

Thanks for everyone's help! I finally got the Weber from hell running pretty close to what I expected. Accelerating through the gears pulls well and AFR levels are real good now at idle and cruise. I got up to 70 mph today without even trying. I ended up with the 60 idle jet and advanced the timing to 5BTDC. I ended up going from 140/140 on the main jets to 150/150. It's running a little rich according to the AFR gauge so I'm going to run a few tanks of Premium E90 and see how the mileage is. I might go with 145/145 or 145/140 but I'm not going to play with it too much if the gas mileage is OK. I learned a lot about how these things work. I now have to remind myself not to put my foot in it so much but it is pretty fun taking off from a stoplight now. I do have a problem with the fast idle but if I can't figure it out - there's not a lot of info online about how to set it -  I might start another thread.

You might consider jetting the primary smaller then the secondary . When you need the punch you will have a big secondary to kick in , but have the smaller primary for MPG . I didn’t see any advantage of going bigger then the 60 on the idle circuit either , it’s just too rich . I’m going to pull my jets again today to actually write down what I have . 

[matrophy]

2 minutes ago, Madkaw said:

You might consider jetting the primary smaller then the secondary . When you need the punch you will have a big secondary to kick in , but have the smaller primary for MPG . I didn’t see any advantage of going bigger then the 60 on the idle circuit either , it’s just too rich . I’m going to pull my jets again today to actually write down what I have . 

60 is what Redline put in it originally. At first is was running lean as hell so I went all the way up to 75 to find out that the throttle shaft was bent and holding the throttle valves open. I went to 55 and it was running too lean. 60 runs a little rich so whattya gonna do? There is a 57 jet available that I might think about trying if the gas mileage is unreasonable. I've heard varying suggestions for the relationship between the primary and secondary mains. Equal, main larger, secondary larger so if nothing else, this probably proves that there are lots of ways to go. 

[Madkaw]

4 hours ago, matrophy said:

60 is what Redline put in it originally. At first is was running lean as hell so I went all the way up to 75 to find out that the throttle shaft was bent and holding the throttle valves open. I went to 55 and it was running too lean. 60 runs a little rich so whattya gonna do? There is a 57 jet available that I might think about trying if the gas mileage is unreasonable. I've heard varying suggestions for the relationship between the primary and secondary mains. Equal, main larger, secondary larger so if nothing else, this probably proves that there are lots of ways to go. 

How many turns out on the the mixture ?