Looking for some Weber 40dcoe base line info

[855r]

Hello been quite some time since I've posted here but been loving my corvair the whole time. I just picked up a rebuilt weber 40dcoe none progressive with adapter for my Spyder. I'm wondering if anyone with a "none" progressive carb could share their main jet, idle jet, accell pump and choke tube size. I just want to compare to what I have now so I could possibly get a jump start to the tuning of it. I do know my weber has #34 choke tubes now and I believe 190 main jet size.

I did install it and was able to get the car to idle after I turned the idle jet screws a couple times but it seemed really rich and would bog and stumble if I gave it any throttle, so I pulled it off and reinstalled the YH so the car is running and driving as of now. I'm in San Diego and it's like a dune buggy heaven out here with quite a few guys that can tune a weber for sure but I would like to see what I can do myself before I look for outside help like that. Thanks in advance for any help.

[thewolfe]

Your choke tubes and main jets are too big. You won't be able to get rid of lean bogging with 34mm chokes. I would try 30mm tubes and 150 or 160 jets to start. Air correctors have an impact on the mix too but at higher rpms. A wideband o2 sensor helps a lot with tuning these as there are so many variables in a DCOE.

[855r]

Thanks for the response. I was a bit off on the information I gave in the first post. I'm use to holley jet markings and saw a number and assumed that's what it was. here are the real numbers.

Main jet 145
emulsion tube f68
idle jet 62f21
choke tubes 34

From your advise I'll pick up a pair of #30 tubes and retest on the car and see if things improve. Once I can get it to run even just "OK" I'll get a bung welded onto my DP so that I can install a sensor. I build up turbo Volvo's too(their fuel injected) so I know the importance of knowing what your fueling is doing. I'll report back when I've made the change.

[thewolfe]

You might want to try different idle jets too. I've never heard of 62f21. Seems funky but I'm no weber guru. 50f8 or 50f9s are what I use but also have f11 emulsion tubes and not really sure what difference the f68 makes. Emulsion tubes will change the rpm range of the transition from idle jet to main jet. Mine is progressive secondary(34mm primary, 32mm secondary chokes) and I spent a fair amount of time changing idle jets, main jets, and air correctors to get a combo that runs really good. It runs rich though which I think is par for the course with a dcoe. I would suggest purchasing a variety of jets and air correctors to experiment with. If you don't now, you probably will eventually.

[miniman82]

62 is a huge idle jet, that thing must have fed a 350 Chevy in a previous life. 50 or 52 idles seem to work on lots of different engines to get you started, for the rest let the wideband be your guide. If it's lean on boost, up the mains. Air corrector deals with fine tuning the main circuit and when you transition from idle to main. There should be a little bit of 'bleed over'; in other words the idle circuit shouldn't stop delivering fuel before the mains come in for obvious reasons, it should leave after the mains pick up to avoid a lean condition. If you want to tune only on idles to get them dialed in, remove the main jet stack and go for a spin.

[thewolfe]

One other thing to mention is float level and fuel pressure which can greatly effect these carbs. You should have no more than 3psi fuel pressure or it will run too rich. Same if the float level is too high.

[855r]

I've been reading just about everything I can get my eyes on about tuning weber's and have even watched a few videos plus got a HPBOOKS "Weber Carburetors" and I now feel that I am an expert.... Just kidding but I did place an order today for 150/160 main jets, 210/220 air correctors, F11 emulsion tubes, idle jets 50F8, and finally #30 choke tubes. I will install the lower number jets and the rest of the parts and go from there. I do have a cheap fuel regulator on the car now as I have an electric pump with the fuel currently set to 3psi. I'll lower it a pound when I get the weber back on.
Once I get the car to be able to drive around the block with light throttle I'll go to my buddys exhaust shop and get a O2 bung welded onto my DP and get a A/F guage. I guess I should also mention that I have installed a E-flow compressor wheel, machined LM compressor housing of course onto my B-flow hot side. Runs way better than the tiny B-flow compressor. Yes I do have a wastegate under the car with a 10lb spring in it now, but as of now the YH carb will only flow enough air to make 7 pounds according to my boost gauge.(autometer) not the almost worthless stock one. Thanks for the direction and I will report back with some results soon I hope.

[855r]

Got my parts just now, looks like I have something to do tonight.

[855r]

I hope your not all sick of me but I do have an update on my parts that arrived today. I now have the Weber back on and the car runs great so far
The new parts really help a lot no doubt about it. I did still have a pretty good stumble/bog at a quick hit of the throttle so I checked out what size Accell pump jets were in and they were tiny, .35's I did not order new ones with my other parts. So I got creative and just drilled one out to .98 the smallest bit I have on hand for a total of 1.33 of pump shot size. I was thinking about it and I figure it doesn't matter if one is bigger than the other on a turbo because they both feed the same turbo inlet. Worked like a charm no more stumble and I heard my wastgate for the first time in second gear. The car feels transformed and yes my clutch did slip I guess I'm making serious torque now. If anyone is thinking of this for their car I'll give all my carb specs for a NON-Progressive Weber 40 DCOE. I still need to get a A/F gauge hooked up so some things may change alittle bit but I must say the car runs really good right now.

#30 chokes/venture
F11 emulsion tube
160 main fuel jets
50F8 idle jets
210 air-correction jets
1.33 total of accell pump jet orifice (.35+.98)
Fuel pressure @ 3psi

[thewolfe]

Good news! My clutch started slipping at full boost in fourth gear after installing my weber. Once it starts it will do it more and more then eventually in all gears which is kind of disappointing but after installing the new clutch it was all good. I went with the spring loaded 6 puck carbotic clutch that Clark's sells along with their 1500# heavy duty pressure plate. I would recommend that clutch as it really grips but you can also feather it. By slipping the clutch and gassing it in first before leaving from a stop I can spool the turbo up and get a really good launch.

[StukintheMud]

Great info, I'm in the process of doing the same set up, except I have a 180/150 combo. How are you controlling detonation? Was also wondering if you did any machining to the weber adapter. It seems to look on the small side. Post a few more pics of your

[thewolfe]

Here's my old setup. I used a weber turbo adapter with a 3" outlet and a rajay e flow compressor and housing which has a 3" inlet. No restrictions there! Detonation is controlled with water/methanol injection in the turbo outlet and a safeguard timing control box. And waste gate of course.

[855r]

Wolf, your set up looks great. All is not so perfect with my car just yet. I drove it around all weekend and discovered that in the heat of the day(90 degrees+) it exhibits a little stumble still. These Webers have always got you thinking. I've ordered some additional idle jets to try and richen things up while on that circuit while transitioning to the next. I'm hoping that a 55F8, 50F9, and last 55F9 will cure this last issue. I am only using my pressure retard can as of now with no pinging heard at all, I'll have to see how that goes. I do plan to cobble together a simple water-injection activated by a hobbs switch after I get the Weber carb fully sorted out. I'm almost thinking that perhaps it's choked down too much with the 30mm chokes. I'll through a wrench in my gears and try installing the 34's that I have just to see what happens after it's running good on the 30's

I've been reading that these carbs like more initial timing advance so I may add a few degrees just to see how the car behaves with pulling away from stop lights signs. If that helps with making no change to the jets then my water injection will be made up much sooner.

[thewolfe]

Yeah they can be fussy. So many variables. A wideband o2 helps a lot to know exactly what's going on at what time with the mix. I don't know if I could have tuned mine without it but I had also never tuned a weber before or any other carbs for that matter besides the old yh which is pretty simple.

[Scott V]

I'll through a wrench in my gears and try installing the 34's that I have just to see what happens after it's running good on the 30's

youll need to change your airs & mains going from 30s to 34's. time to order more jets.

I've been reading that these carbs like more initial timing advance so I may add a few degrees just to see how the car behaves with pulling away from stop lights signs.

stock turbos are @ 24 btdc. i wouldnt run more than 26 unless you take it out of the top.

-Scott V.

[855r]

I'm back and I made some great progress on the tip in stumble I was having. I replaced the idle jet with a 55F9, which did help with the stumble to make it less severe but was still there "sometimes". What I noticed especially on a series of dips near my house that I can just cruise through at about 25-30mph in third gear very light throttle was on the rebound the engine would literally almost quit as soon as the car leveled out power back on. I thought about it and came to the conclusion that my float level must be way too low and fuel was sloshing away from the emulsion tubes starving the car for a split second. Then with that in mind the slight tip in stumble was always with a slight acceleration which would move fuel towards the rear of the car in the float bowl. I have been assuming that it's correct this whole time. So I checked it.

It was so off, not even funny. My book says to put it at 8.5mm in the hanging position and it was 15mm. Basically my float bowel was probably less than 2/3rds where it should have been. I set it to 9mm and it's really good, no more trouble at all. Drove the car back through the dips, perfect, taking off from stand stills it's smooth running. I feel like an idiot but am glad I finally checked the level. So now I'm thinking the 55F9 jet may be too rich and masked the real problem. I'll swap it out with the leaner one tomorrow and see how she runs.

I'll say this about my whole experience, don't over look the basics on these weber carbs. Any drivability issue make sure the float level is correct. Many circuits depend on it.
Also I haven't messed with the timing at all. Its at 24 btdc now and runs fine so I'll leave that alone. I still need to fine tune with an A/F gauge but that will come soon. I have to start saving for those new clutch parts. This car is a clutch slipper big time while making over 7 pounds of boost.