Initial review of MSA weber 40 DCOE carb kit

[Zedyone_kenobi]

Don't know what idle is right for webers. I have read about 900 rpm is normal.

I had no surge on my Ztherapy SUs bud. I did have surge on my original carbs. The surge I believe comes from worn throttle linkage rods.

Still the cable feels great!

[rocketdog]

Small detail that you'll get to, but take some acetone and a rag and get that bright blue marking paint off the top of each carb. Comes off easily. Unsrewed my old manifold studs today...piece of cake... took only 1/2 hour. New ones arrive tomorrow. Started assembling the linkage onto new maifold and switching the sides on the carbs where the linkage connects. Have a sheetmetal company as one of my tenants who will fab a heat shield for me out of SS or aluminum...for free...which anyone can afford. Still planning out my SS braided lines and AN fittings. Can't wait to hear and feel the difference.

[doradox]

Your high idle is exacerbated by the high initial timing you are running. I wouldn't recommend dropping it back down though. Nice job on the install. Looks great!

Steve

[Zedyone_kenobi]

That occurred to me Doradox, and your right, I would not come off 14 Deg BTDC. I plan to run about 17 on the new motor with a re curved dizzy or a mallory.

I just need to figure out the jetting now. I am still getting a lean stumble when I jab the throttle as fast as I can at low rpm. This is normal for the most part as the intake velocity is not optimum, but I have not done any pulls while monitoring the wide band yet. I am just do thrilled to have a car that is happy to rev and drive and sound so amazing. The midrange is a definite improvement over the SU's. It feels very strong!

I am still playing with the linkage and spring tension to get it where I like it. It is all about angles!

I still get a bit of pooling on my heat shield, but I think that only happens when I slam open the throttles and the engine falls flat. I mean it makes sense. I am dumping gas into the main circuit via the accelerator pump while the intake velocity drops to nil. Where else is the gas going to go but out of the carb?

[Zedyone_kenobi]

I love these carbs!!!!

[LeonV]

Drove the car today. WHAHOOOOO

I first disconnected the linkages from the throttle bar on each carb. Then I unscrewed progression hole cap. I adjusted each throttle plate so that none of the first hole was uncovered, but was just going to be uncovered upon first movement of the throttle shaft. I then unscrewed the idle mixture screws one full turn as a way to get the car to idle at all with only a 1/4 or 1/2 turn from fully seated.

THe car settled into a nice 1100 rpm idle once fully warm. I could not fit my new synchronizer on the air horns as there is just no room, so I ordered the snorkel for it today. So I used my unisyn.

Now as you know Weber guys, the only way to increase or decrease air flow into the car is to move the throttle shafts. BUT that may uncover a progression hole. My solution to this was to start over and adjust all the idle speed screws so that I had a little more play area before I uncovered a progression hole and then start to sync the air flow. Well long story short, I got them all pretty close, but my unisyn varies from run to run, so I am going to stop fiddling with air flow until I can use my real tool. First drive, I was ultra lean. I would go completely dead with any application of the throttle at all. Like shutting down the engine all together, and my wideband would read 20:1. OUCH. So I adjusted the idle mixture screws a half turn at a time until I was reading about 12:1 at idle. Then I set out on my next drive.

WOW, I was thrilled with the response. Pulls very nicely. I was almost scared to rev it with part throttle to my 4500 rpm point. But I did in second gear and it was smoooooooooth.

Let me reiterate. I have ZERO popping through my exhaust at 4500 rpm at part throttle.

My only problem now is that I do not have the pedal adjusted correctly, as I never get full throttle. I will need to get my wife out there to help me do that. But the car needs no choke at all to start from cold. I have not even checked the timing, but the driveability is amazing.

THe sound.. heee..heee.. I am still smiling.

I just wish I could get them to idle lower. I am stuck idling at 1000 rpm now. I will play with that idle speed circuit again when I have more time. But she is running and looking great.

Oh I discovered slow leak on my fuel filter added before the pump by the tank! DRAT. I should have used teflon tape on those fittings.

That's awesome, gotta love triples! It's good to hear that your problem is finally alleviated, as I've thought it was a lean mixture issue from the moment your problems appeared.

Never use PTFE tape on fuel fittings! It will break down and eventually cause a leak without you knowing.

The 1000rpm idle is fine. Progression holes are what really determine idle speed (along with static timing), since correct transition circuit operation is dependent upon initial throttle position. If your throttle plates are oriented correctly, I wouldn't touch a thing.

For syncronization, as you saw, the Weber SK tool is head and shoulders above the Unisyn. I'd never even try to use a Unisyn on a set of triples, let alone dual SUs! You should be able to fit te SK just fine with the air horns removed.

That occurred to me Doradox, and your right, I would not come off 14 Deg BTDC. I plan to run about 17 on the new motor with a re curved dizzy or a mallory.

I just need to figure out the jetting now. I am still getting a lean stumble when I jab the throttle as fast as I can at low rpm. This is normal for the most part as the intake velocity is not optimum, but I have not done any pulls while monitoring the wide band yet. I am just do thrilled to have a car that is happy to rev and drive and sound so amazing. The midrange is a definite improvement over the SU's. It feels very strong!

I am still playing with the linkage and spring tension to get it where I like it. It is all about angles!

I still get a bit of pooling on my heat shield, but I think that only happens when I slam open the throttles and the engine falls flat. I mean it makes sense. I am dumping gas into the main circuit via the accelerator pump while the intake velocity drops to nil. Where else is the gas going to go but out of the carb?

Intake velocity does not drop to zero unless your engine isn't spinning. You should be able to floor the throttles in high gear and low rpm and have your car lug, but not shut off. This is discussed in Keith Franck's "White Paper" for tuning the Weber DCOE, in the Sidedraft Central "Files" section. You can eliminate all stumbles as well if you read and follow along!

Oh, and video or it never happened.

[rocketdog]

Boy, Zedyone, you do have a fug snit between the air horns and the strut! Just tested the fit on my late 260 and there must be 6 inches to the strut. Got the manifolds installed today. New studs went in easy. Used that copper spray but masked everything off. Glad I did as it goes everywhere like spray paint. Manifolds fit pretty easily, just had to grind off a bit of one corner of the Cannon intake.

[Mike W]

A couple of comments on the fuel pooling you have observed on your heat shield.

I have seen this same phenomena on my setup with two different sets of Webers. I did some research on this on the Sidedraft Central news group and apparently fuel leaks out of the front of the DCOE's is a fairly common problem. There is a thead where you can read about it here:

http://autos.groups.yahoo.com/group/sidedraft_central/message/5412

Given that I had the same issue I decided to try and fabricate the rubber washers that the author of the post above identified as a solution to this problem. They were a little tedious to fabricate, but I made and installed them to see if they would resolve the leak issue. I would say that I had some minor improvement but could never really get the washers to fit tightly enough to eliminate the problem. So I decided to go another route.

I took some pretty precise measurements of the air horn OD, the choke body ID, and a few other areas and identified a couple of O Ring sizes that could be used to really seal off this area. I purchased some O Rings from McMaster Carr that had and ID of 44 mm and were 2 mm thick. The McMaster part number was 9262K529. I also purchased some o ring lubricant which I applied to the parts before assembly.

So I put the O Ring over the inner part of the air horn before inserting into the carb body. I find that it takes a little pressure to "force" the O Ring into the channel between the air horn and the carb body, but you can actually feel it snap into place when it is fully seated. Tighten down the air horns and you are good to go.

After driving with this configuration I can say that it solves 95% of the problem. I might see a few drops of liquid on the heat shield after 50 - 100 miles of driving so I think this largely solves the issue.

On the Sidedraft Central forum however you will also read about the notches that are cut into the carb body to allow for alignment of the choke and aux venturi and the opening they provide to exacerbate the fuel leak problem. I posted some questions about this issue and proposed fix which you can read about here:

http://autos.groups.yahoo.com/group/sidedraft_central/message/5456

Presently my solution only uses the O Rings and does nothing specific for the notch issue, but from my experience so far it looks like this solves 95% of the problem.

Hope that helps.

Mike.

[Zedyone_kenobi]

LeonV Video is coming Saturday!

I have to get my Go Pro working again. After I find it. Where ever it is...

I may just use the iphone! Its HD and my go pro is not.

Also I am not using the white PTFE tape Leon. I have some aviation yellow pipe thread tape. IT says it is fully compatible with silicones, hydraulics and petroleum products. So I hope I am okay. I have a hard time getting NPT fittings to NOT leak. I only seem to have about a 70% success rate regardless of how hard I torque them.

Mike, GREAT thread, and my pooling is very minor right now. Almost a non issue. But I have the air horns that slide all the way into and around the venturi (or is it the choke). I have the 151's DCOE

I am pretty sure I need to up my main jet. I was reading Mr Franks paper and at low rpm (2000 rpm) in 4th gear holding the throttle steady my AFR were right at 14. He recommends 12.5, and I tend to agree with him on that. I am currently running a 130 main and 170 air corrector. My overall driving is darn near flawless. I do have a hint of a hesitation on the progression around 1800 rpm, but I mean it is slight, and not consistent. I think I am only a few jets and a few twists of the screws to have a perfectly fine running set of webers. Really the more I read, the more I think the hesitation issue in mid rpm thing is blown out of proportion. It seems a perfectly logical thing to tune out. My car was darn near running perfectly 30 minutes from first starting it. The Webers are do darn Logical. I absolutely LOVE them.

Before I mess with jets though, I am going to verify fuel level of the floats. Not sure if I am going to do it the weber way, or the Mr. Frank way. I do not know where to get a piece of acrylic that small.

Edited April 20, 2012 by Zedyone_kenobi

[olzed]

Regarding NPT threads leaking. I tried thread tape on NPT and BSP hydraulic fittings, many times, but always went back to using hemp.

I owned and worked on excavators for 30+ years, and always used plumbers hemp on tapered thread fittings. Just a few strands teased out and wound around,to half fill the thread, will give a fitting that can be tightened into a position that suits, and will not leak with pressure in excess of 2000 psi.

Thread tape seems to compress too much and gives a not too positive feel when tightening the fitting. If you are using a bend that has to finish in a certain position, hemp will give you that ability, and can even be backed out a little and still not leak.

Thread tape will be cut into a useless mess when the fitting is screwed in, whereas hemp fills the thread and will not be squeezed out.

I still have a bundle of hemp that I use when the need arises. It's 'old school' but still does the job.

FWIW

Brian.

Edited April 20, 2012 by olzed

[LeonV]

LeonV Video is coming Saturday!

I have to get my Go Pro working again. After I find it. Where ever it is...

I may just use the iphone! Its HD and my go pro is not.

Also I am not using the white PTFE tape Leon. I have some aviation yellow pipe thread tape. IT says it is fully compatible with silicones, hydraulics and petroleum products. So I hope I am okay. I have a hard time getting NPT fittings to NOT leak. I only seem to have about a 70% success rate regardless of how hard I torque them.

Mike, GREAT thread, and my pooling is very minor right now. Almost a non issue. But I have the air horns that slide all the way into and around the venturi (or is it the choke). I have the 151's DCOE

I am pretty sure I need to up my main jet. I was reading Mr Franks paper and at low rpm (2000 rpm) in 4th gear holding the throttle steady my AFR were right at 14. He recommends 12.5, and I tend to agree with him on that. I am currently running a 130 main and 170 air corrector. My overall driving is darn near flawless. I do have a hint of a hesitation on the progression around 1800 rpm, but I mean it is slight, and not consistent. I think I am only a few jets and a few twists of the screws to have a perfectly fine running set of webers. Really the more I read, the more I think the hesitation issue in mid rpm thing is blown out of proportion. It seems a perfectly logical thing to tune out. My car was darn near running perfectly 30 minutes from first starting it. The Webers are do darn Logical. I absolutely LOVE them.

Before I mess with jets though, I am going to verify fuel level of the floats. Not sure if I am going to do it the weber way, or the Mr. Frank way. I do not know where to get a piece of acrylic that small.

I'm glad you have discovered the inherent "awesome-ness" of the Weber DCOE!

With regard to float setting, Keith makes and sells the tool for $40 or so through his online listings. I'm planning on getting some Hypojets and possibly e-tubes. He is local to me and I've offered up my Z to do some e-tube testing.

[madkaw]

This thread is really getting me worked up to get my Mikunis going. Sounds like my shorty manifold was the only option if you want a cold air box since things are so tight with the Webers.

I also wonder if the Mikunis will be easier to dial in since they have accelerator pumps.

I hope you spend some money to dial your Webers in on a dyno, I think it would be worth the money, plus interesting reading for us!