DCOE Tuning Help

[2002Scoob]

Caution... What one calls a transition jet, another calls an idle jet.

 

And while a pump jet will help fill a hole on on fast throttle inputs, it won't save ya if your other jetting isn't right.

 

Pump-jet is the one under the taller cylindrical brass cover with the flathead slot, forward of the 'transition' cover which has your progression holes.  It's got a long and a short skinny section with a fat section in the middle with a flat. And the Flat faces forward. 

 

Don't forget the little alloy washers! I bought those in bulk, so every jet has it's own now so I don't have to fiddle trying to get a razor-blade behind it to wiggle 'em off. 

Edited September 16, 2020 by 2002Scoob

[2002Scoob]

Just givin' this thread a bump   @Stevenc22 , any luck? Just curious if you've stumbled across any jetting 'aha!' moments. 

 

I'm debating to wake up Brunhilde from her slumber for a few more rounds of tweakin' around before I decide if I drive her up to Berlin to visit a friend, or just put her away for winter storage to be more environmentally responsible and take the train.

Edited September 27, 2020 by 2002Scoob

[Stevenc22]

My jets arrived but the spring on my garage door decided to snap, locking my cars up for the weekend. 

 

Only thing i have left to try is a 135 main and then at least look at what pump jet i have installed...

[Stevenc22]

On 9/27/2020 at 5:38 AM, 2002Scoob said:

Just givin' this thread a bump   @Stevenc22 , any luck? Just curious if you've stumbled across any jetting 'aha!' moments. 

 

I'm debating to wake up Brunhilde from her slumber for a few more rounds of tweakin' around before I decide if I drive her up to Berlin to visit a friend, or just put her away for winter storage to be more environmentally responsible and take the train.

 

Okay, i think I'm going to call this issue almost solved.

 

The 135 main jets really did help. I still have some partial throttle lean hesitation, but im able to easily accelerate through that and under heavy load the car is seeing low 11:1 AFR. 

 

So in the end im using

135 Main

190 Air

F965 Idle

F16

34 Chokes

 

I appreciate everyone's inputs. Good thing im making progress becuase im running out of jet sizes to buy.

 

[Son of Marty]

That's ok you can get those jet boxes that have 2 stories. Just kidding everyone with a set of dcoe's has a collection like that I always wanted to start a jet loan library, but I'm afraid that it would get outa control pretty quickly.

[2002Scoob]

Not a bad little collection of Jets :) 

 

11:1 is still a bit rich. At what RPM, and is that WOT?

 

I was always aiming for 12.5-13 WOT at mid/higher RPM's. Can't really say exactly what RPM's, cuz I don't have a tacho.... Boy wouldn't that help. And a TPS sensor... and a few hundred bucks and a guy with a dyno who's local and been tinkering with these things for the last 30-40 years and knows more than me. 

 

hah. 

[Golfcar]

On 9/28/2020 at 5:55 PM, Son of Marty said:

That's ok you can get those jet boxes that have 2 stories. Just kidding everyone with a set of dcoe's has a collection like that I always wanted to start a jet loan library, but I'm afraid that it would get outa control pretty quickly.

 

Just cruised this and seems like you are making progress so won't but in. An FYI. You can buy a drill set for jets. I got tired of buying jets mostly the wait time. If you need bigger you can just drill them out. I then use a inscribe vibrating tool to label them so my senior mind doesn't forget what size is in the frigging Webers. HTH. Just helped another guy on here and he is getting closer. Steep learning curve that's for sure. 

Gary 

[75duce]

Sounds like your float level may be a little low .  

 

25mm below the the top for the main jet tower is a good place to start.

you want the fuel to be just a few mm below the spillway so the e tubes don’t have to suck the fuel up so much .

 

the air corrector jet is the bleed for the main jet and will control the main jet tip in .

Top end high rpm is comtroled by the main jet.

 

one thing to keep in mind is the carbs are designed for performance and not economy , don’t get to hung up on afr readings and give it what it wants . 

 

4 times the Venturi size will give you your main jet size to start with and most of the time it is perfect 12.5 afr .

 

i like to set my cars up with a slightly rich idle not best lean idle . This will make the transition in the progression smoother. 

 

One thing to also look at is if the throttle butterfly is centered over the first progression hole . If not the engine is going to go lean as soon as you move the throttle. Requiring a large idle jet and lots of turns out on the idle mixture screw to overcome the flat spot . A tool was designed to fix this problem by drilling a new progression hole closer to the butterfly. I have use this tool on many cars with good results.

[2002Scoob]

2 hours ago, 75duce said:

I have use this tool on many cars with good results.

 

Any info on where to get said tool? :)

[Stevenc22]

4 hours ago, 75duce said:

Sounds like your float level may be a little low .  

 

25mm below the the top for the main jet tower is a good place to start.

you want the fuel to be just a few mm below the spillway so the e tubes don’t have to suck the fuel up so much .

 

 

POST OF THE YEAR!

 

75duce nailed the problem on the head. My float was low by at least 3mm. Once i adjusted the float, the lean holes are completely gone. Heck i was even able to downsize the idle jet 1 size since i was now rich everywhere. 

 

[75duce]

 

 

https://www.webstore.com/item/Weber-DCOE-Progressive-Hole-Drill-Fixture/96438149

 

[man_mark_7]

On 9/30/2020 at 11:48 AM, 75duce said:

......

 

One thing to also look at is if the throttle butterfly is centered over the first progression hole . If not the engine is going to go lean as soon as you move the throttle.

 

@75duce can you describe what you mean by "centered"? Should the thickness of the butterfly plate be exactly aligned with the first progression hole so that as soon as you start to open the throttle you begin to expose the progression hole?

[75duce]

Yes  aligned so as soon as you open the butterfly the first progression hole is being exposed.

[Hans]

I've wondered about that 25mm measure in the past, given possible fluctuations in level before you get in to measure. Better to take the top off.

So what gap did you set? I prefer to use something that goes right across the cover (with gasket). 

Also, somebody posted some helpful pics a while back of the progression holes lit by a flashlight. Any chance of those coming back?.

Did you floats have the little plastic bumps right where yo umeasure?

[man_mark_7]

46 minutes ago, Hans said:

I've wondered about that 25mm measure in the past, given possible fluctuations in level before you get in to measure. Better to take the top off.

So what gap did you set? I prefer to use something that goes right across the cover (with gasket). 

Also, somebody posted some helpful pics a while back of the progression holes lit by a flashlight. Any chance of those coming back?.

Did you floats have the little plastic bumps right where yo umeasure?

I found poor correlation setting my plastic floats to the spec. 12mm from the underside of the top plate and obtaining a fuel level 25mm below the top edge of the float bowl. I made a probe with an adjustable lip to stick into the emulsion tube hole. I dip the probe in then pull it out and tap it onto a paper towel. If I see a wet dot on the paper towel, I know it hit the fuel. I can move the lip up and down to see what the fuel level is. Thankfully if I find the fuel level is 3mm low, bending the floats up by 3mm seems to do the trick so I don't have to keep going back and forth taking the covers off over and over.

 

I also use an electric fuel pump so I just leave the emulsion tubes out, turn on the fuel pump until the fuel level stops moving, then measure.

 

I found that I was closer to the 8mm spec for brass floats vs. the 12mm normally used for plastic floats to hit the 25mm spec.

 

mm