The Brunhilde Tuning Thread

[zinz]

Before heading out to the beirgarten, download this and read the section on DCOEs about 4 times

 

http://www.lainefamily.com/images/WeberTuningManual.pdf

 

Fuel level instructions on page 45

 

Enjoy... this is mandatory reading for those who want to tune their own DCOEs.

 

Ed

[2002Scoob]

Haha, you missed me too late already here. But as soon as I'm home it's homework!





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[TobyB]

Quote

 I'd like to avoid ordering a whole slew of stuff if possible. 

It's impossible.  

You end up with a bucket of parts, no matter how hard you try not to.

Pegasus in the US used to sell a complete "jet kit" which you could

then return, minus the parts you used.  It 'seemed' like expensive jets-

until you factored in all the spares you didn't end up needing! 

Then it was a stonkingly good deal.

 

t

 

[AndySals]

That's some view!

[Simeon]

Don't forget to check for vacuum leaks when you have had your pretzel. If you are using just thin paper gaskets between the carbs and manifold then it wouldn't take much of a warp to create a leak. 

[2002Scoob]

So I pulled my covers just now to measure and confirm float heights, both are set pretty much dead-nuts even to 8.5mm.

 

Do you guys think that, because I've been primarily on the progression circuit, and the reveal to the progression holes was mismatched front-to-rear as above, that could have been the driving reason why I was so rich front-to-rear?

 

I've set the forward carb float at ~8.7mm

 

And the rear and closer to 8.1, we'll see if that makes a difference.

 

I also ordered a new set of 45f8 idle jets to go along.

 

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[zinz]

I think, Jeff, that at this point, you are past the theory and baseline measurements of the initial set-up.  You are now in the actual tuning process and the fun begins.  Try one thing at a time and log your results.  

 

You've said these were not a "matched set" of DCOEs, so you may not be able to treat both carbs the same as far as jetting...maybe you will.  The carbs are unbalanced in the videos, the engine is shaking too much and you can hear the stuttering.  You checked plugs which showed one carb is rich, the other is lean.  This is where checking the color/condition of your plugs gleans more precise information than a single WBO2 sampling the entire exhaust plume.  

 

You've changed the float levels... now go run it. As Toby suggests, don't be afraid to run the revs up.  You don't have to flog it, but roll into the throttle and work the engine.  If you're worried about it not starting after sitting, always bring it home to save on towing

 

While you are waiting one new idle jets...

 

You already re-checked your linkage and found where something was slightly out of adjustment... that should have helped.  Sync the carbs at 1500-1750 rpm and check results... perhaps they seem more balanced?  If so, adjusting mix screws can help solve the out-of-balance at idle.

 

Try turning the mix screws in on the rich carb and see how it reacts (your lean carb won't likely benefit much from this experiment).  Go 1/2 turn, maybe a full turn-in to see how the engine reacts. Then make adjustments +/- in 1/4 turns... allowing the engine to settle down after each adjustment.   Each cylinder will draw differently and need slightly different metering through the idle circuit. The baseline Weber mixture settings of 1.5 turns out is simply a starting point.  Take your time here... listen and watch how the engine reacts to your adjustments.  You may need to increase the idle speed very slightly to achieve your goals, but not so much that the throttle plate opens the first progression hole.

 

You allude to the progression circuit... if all you've done is putz around less than 3000rpms... the idle jet is metering most of the fuel in this rpm range. This is the circuit we are attempting to solve at the moment. Later on, when you ask about a flat spot at 3500 when jumping on it... we'll address E-tubes and mains and how they work together.

 

Change one thing at a time and log results... it's easy to confuse your #s and findings later on if you don't write them down.

 

Good luck, you'll get it soon enough.

 

Ed

 

 

[2002Scoob]

I'm beginning to think that either myself or Brunhilde is cursed...

 

A small update-

 

I ordered the 45F8' Idle jets, they're not here yet.

 

But I did as I mentioned last night, and adjusted the float levels front and rear, then spent about an hour and a half fiddling with mixture screws in an attempt to smooth out the idle while keeping AFR pulses as close to 12.5-13.5 as possible.

 

It ended up requiring 2.75-3.25 turns out across the board, and she still sounded like she was missing.

 

Then to add to the confusion, I again pulled the plugs to see how things looked and 1-2 look rich, 3 is meh... unfortunately all are a bit oil fouled... (but I already had such suspicions about the bottom end.)

1

2

3

 

But 4..... looks clean. As in new. As in, nothing is burning.

 

What is going on??

 

With the timing light, it's showing that I'm getting spark and current... could it be there's just no fuel?

 

I got off the phone with Ireland Engineering thinking maybe it's the dizzy. But Jeff there thinks it's gotta be carbs.

 

With the AFR gauge, I would end up getting an occasional pulse up into the low 15's that I was trying to tune out... If one cylinder is down, perhaps it just pumping air is leading me to enrich the other 3 cylinders too much to compensate?

 

I'm thinking just to pull them and start looking deeper, but I'm not sure where to begin.

 

 

 

 

 

 

 

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Edited April 13, 2017 by 2002Scoob

[jireland2002]

You've done a good job of checking and documenting.  Used carbs are always a crap shoot.  It sounds like the front carb may be flooding and #4 is not getting much fuel.  Fiddling with fuel level and idle jets may get the front carb under control.  Years ago when we actually worked on customer cars we learned never to install customer supplied used carbs.  

If you have a infared temp gun you can check the temp of the header at the exhaust port.  It will tell you if a cylinder is cold (not firing or very rich) or hot (lean)

You can check the fuel level in the carb by measuring the level in the jet well.  Try --  Run the engine at a higher rpm and shut it off and check the fuel level.  Then come back 10-15 minutes later and check again.

I assume you have adjusted the valves after running the engine a couple hours.  If not do so.  The valves will tighten up as a new engine is run in.

[2002Scoob]

2 hours ago, jireland2002 said:

You've done a good job of checking and documenting.  Used carbs are always a crap shoot.  It sounds like the front carb may be flooding and #4 is not getting much fuel.  Fiddling with fuel level and idle jets may get the front carb under control.  Years ago when we actually worked on customer cars we learned never to install customer supplied used carbs.  

If you have a infared temp gun you can check the temp of the header at the exhaust port.  It will tell you if a cylinder is cold (not firing or very rich) or hot (lean)

You can check the fuel level in the carb by measuring the level in the jet well.  Try --  Run the engine at a higher rpm and shut it off and check the fuel level.  Then come back 10-15 minutes later and check again.

I assume you have adjusted the valves after running the engine a couple hours.  If not do so.  The valves will tighten up as a new engine is run in.

 

Thanks for Chiming in, Jeff, and thanks for taking the time to talk over the phone. Much appreciated. 

 

I'll give your recommendation a shot tomorrow, then I think I'm going to pull the carbs to examine some of the things we talked about, like the mixture screw seats. 

 

Coincidentally, we do have a infa-red FLIR camera/gun in our office I can try out. 

 

Perhaps something is lodged in the Idle/progression circuit on #4 that's keeping it dry? Maybe a shot of compressed air can blast it free, who knows. 

 

I'm open to any and all suggestions at this point, and will digg-in as deep as I can.

 

And yep, I've been periodically checking valve lash

 

Fingers crossed the carb bodies aren't junk!

Edited April 13, 2017 by 2002Scoob

[zinz]

+1 with Jim's recommendations.

 

yea... #4 is dead...as in not getting any fuel...WTH?  The remaining plugs are obviously rich...    #3 is wet with fuel.  Looks like you gotta wait on those new idle jets, for sure.

 

Look on page 24 of the Weber tuning pdf I sent you, it shows how fuel is delivered through the carb for each circuit. You should check for a blockage; #4 is not delivering at all, it appears.  Was all your recent tests performed at idle? Didn't run it up at all?  You could back-flush #4 by removing the mixture screws and idle jets and blasting the mixture orifice with carb cleaner... some will go directly into the carb throat, but perhaps it will dislodge whatever's in that orifice.  Don't use any wire to probe around... you'll only damage the orifice.  Perhaps there is a blockage at the inlet in the fuel bowl...

 

Here's some Google images showing how fuel is routed thru a DCOE.

 

Starting Device (you have disabled yours, but i included this nonetheless)

 

   

 

 

Idle:

 

Acceleration Phase:

     

 

 

Full Power:

 

  

 

 

 

[TobyB]

Sure you have an intake manifold gasket on #4?  That'll cock the manifold, and you'll get a huge air leak.  And plugs that look like that-

 

your afr meter sees average oxygen, so you're way over- rich on 1- 3  (or 1&2, with #3 along for the ride)

 

Something's all wrong with #4- time to get out the endoscope.    Pull the plug, and confirm that it's sparking.  Then go after the carb.

 

You'll find it.

 

It will be something that makes you smack your forehead.

 

t

 

[2002Scoob]

52 minutes ago, TobyB said:

Sure you have an intake manifold gasket on #4?  That'll cock the manifold, and you'll get a huge air leak.  And plugs that look like that-

 

Now this I'm 100% positive of, she's button'd up tight. There's gotta be something blocking up the #4 Idle/Progression circuit. 

 

And, as you said, the Wideband is seeing an average of all 4 cyl. 

 

1-3 are way over rich, but If #4 is just pulling air and very little fuel wouldn't that average out a higher-than-actual AFR? As in, i'm compensating on being overly-rich with 1-3 for the super lean #4-me thinks that could be why I'm having to be so far out on the mixture screws.

 

First things first tomorrow is trying to figure out if there's an obstruction in that circuit.

 

 

And Ed, also thanks!  Looking through the images above, there's little else I think that could be causing it... I actually have that same Tuning manual document printed out and on a clipboard in my shop  I've been referencing it since I rebuilt the carbs and its fantastic. 

 

Stead as she goes...

2 hours ago, zinz said:

 

Idle:

 

Acceleration Phase:

     

 

 

[Son of Marty]

Check the number 4 aux venturi for orientation it can be installed backward or with the fuel passage on the bottom cutting of fuel flow on the main circuit. 

[2002Scoob]

I think I've done it...

 

And yes, Toby, 

 

 

On 4/13/2017 at 11:33 PM, TobyB said:

It will be something that makes you smack your forehead.

 

 

I started off Friday focused on it could only be one thing that was holding Brunhilde back from making sweet, sweet BRUUNH BRLUUUNH noises, and that was a clogged Idle/Progression circuit.

 

Just to double check all suggestions made, I have all gaskets installed properly, and I re-checked torques on the Carb-manifold, and manifold-head. While everything could use a little snugging down (likely due to gaskets compressing) nothing was particularly loose. 

 

I then moved onto the carbs, removing the Idle Mixture screw on all 4 chokes, and peering in as best I could to see if there was anything that looked like heavy deformation of the needle seats, and all 4 look pretty good and even.

My confidence bolstered, I pulled the progression cover on #4, and shoved the hose from a can of Carb cleaner into the orifice,

removed the idle jet...

And fired away. There was some obvious back-pressure as if there was some blockage, but eventually a solid stream of carb cleaner came shooting out into the fuel bowl. Success!

 

Excited as I was to think that I might have fixed my problem, I also had the air-filter plate assembly off so it was MUCH easier to get to the throttle plate spindles, so I began the slow and tedious task of torquing the forward carb's butterflies back into sync. 

 

BTW, it takes a scary amount of twisting to un-twist a spindle even a small amount... Like, this can't be good what I'm doing and i'm going to break something twist. But sure enough, after lots and lots of twisting/checking alignments against the forward edge of the first progression hole, I got them what I feel is reasonably close but could still use some more pulling.

 

I did this the same as all my sync-checking, with an LED flashlight aimed down the barrel you can adjust the plates with the idle adjustment screw to where just a speck of light is visible at at the edge of the first progression hole. Roll the plates forward, torque/cringe, check, adjust, torque/cringe. Wash. Rinse. Repeat.  Below you can see what I ended up with after about 5-10 minutes of twisting. There's a hair-more light on the left than on the right which, if you scroll down, corresponds with the readings I ended up with.

 

And after all this... Pulling the throttle plates forward multiple times (essentially pumping fuel into the chokes with each pull) thoroughly flooded the engine making it impossible to start, so I moved on to my latest project, trying to make the cleanest cable routing possible for the spark-plug wires. 

 

I personally can't stand messy wiring, so this is my first stab at cleaning up that area. I've got a bit more refinement to do, but she's getting close. I'll likely refine the concept a bit further, and maybe make a few sets if anyone is interested!

 

Afterwards I left her overnight with the plugs pulled so that all the fuel I'd dumped into the motor from my tweaking could evaporate. The next morning I went in confident I'd solved the problem, but I was again wrong.

 

I started her up, she ran rough and sounded like she was missing still. Sure enough, after about 30 minutes of Idling and revs, #4 was still very much lean and not firing, so I started to focus on other contributing factors, which is where I had my 'Aha!' moment.

 

Before I pulled the head and started this project, I was having multiple issues including intermittent rough idle/stalling combined with flooding from a leaking original Solex DIDTA that was in need or rebuilding/replacing. Given I was going down the road I've been on, I didn't put much effort into trouble-shooting the issue. 

 

For those of you that have an Ireland Shorty DCOE manifold, on the back of the #4 is the brake booster vacuum line... I don't know why I didn't think of it sooner, but any vacuum leak or a failed booster could easily contribute enough of a leak to create a lean situation on Idle, especially when paired with the clogged Idle/progression issue I previously cleared out. So to test I pulled the check-valve and inserted a bolt into the hose in it's place. Sure enough, that was enough to bring #4 back into the equation. 

 

Unsure if it was either the check-valve, or the worn fitting-to-gasket connection at the actual booster, I swapped out the check-valve for a known working one, applied a bead of RTV around the fitting at the booster/gasket (not Ideal, but whatever), fired her back up, and went back to adjusting mixture screws and eyeballing my wideband. For the first time, turning the mixture screws on #4 registered not only a change in idle, but also AFR, and after about 20-30 minutes of hair-tweaks to all 4 mixture screws I was able to get a relatively smooth idle, and AFR's settled between 12.5 and 13 with no high-low spikes, where before it was ranging between 11.8 and having spontaneous spikes to 15 (likely from an in-active #4)

 

AND, even with all my torquing and pulling on the #1 throttle shafts, I still don't have perfectly matched numbers, but its allot closer than before with about spot-on 5, and a hair under 6 for 1 and 2. I still have to tweak the throttle shafts on the rear-ward carb as well to even those out, but I'm honing in! After I torque the shaft between 3+4, I'll see where there at, then look at tightening up the forward carb so there more synced. But in all honestly, now that she's running on all 4 cylinders the idle is pretty darn smooth, and getting smoother as I hone-in. 

 

 

Afterward I got the smoothest idle I've achieved thus-far, I took her out for a spin around the Brewery and then later home, and she's pulling quite healthily now! None of the bogging-down nonsense that I'd experienced before when I was likely on 3 cylinders. I'm going to drive her some more before pulling the plugs again, and see where she's at, but I'm definitely feeling a lot better about the situation!

 

 

Thanks again for all the help, suggestions, and support. I'll be sure to check in on further updates/tuning, and perhaps when the weather gets better some driving action