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Thu May 17, 2012 7:21 am

Im trying to get my Single Weber 40 DCOE working on my 1955cc dune buggy engine. I cant fingure it out. and could use some help.
-76mm Crank
-90.5 Pistons
-044 heads (42 x 37.5 mm)
-Eagle Racing Cam (Adv. Duration 296° / Dur. @ .050" 256° / Lift @ cam .420" / Lift w/1.1:1 Rocker Arms .462")
-009 distributor
-compu-fire ignition
-8:1 compression ratio
-Garrett Airresearch T3 (.48 A/R , 42. Trim)
I think i got everything here. if not let me know

Thu May 17, 2012 7:23 am

Well i thought i had everything is the post but after reviewing i forgot to add the most important question. Im looking for Jetting for the DCOE

Thu May 17, 2012 7:27 am

Wouldn't a single 40 DCOE be jetted the same as a 40 IDF? Same engine, same altitude, exhaust, and throttle size?

Thu May 17, 2012 8:52 am

I met 40 dcoe 30 Ven , 1915cc engine W120 1,25:1 and it worked perfectly.
It is important to calculate how much CFM carburetor you need to configure
40 DCOE , 36 mm, 350 cfm at 1.5" Hg
40 DCOE , 34 mm, 346 cfm at 1.5" Hg
40 DCOE , 32 mm, (ALFA romeo 2000cc )336 cfm at 1.5" Hg
40 DCOE , 30 mm, 316 cfm at 1.5" Hg
40 DCOE , 28 mm (Fiat 2300S), 279 cfm at 1.5" Hg
40 DCOE , 26 mm, 241 cfm at 1.5" Hg
40 DCOE , 24 mm, 202 cfm at 1.5" Hg

Thu May 17, 2012 10:20 am

:idea: Run by these numbers...............

Air............190/200
Emulsion...F11
Mains........145
Idle Jet......50F9
Start Jet....60F5
Pump Jet...40
Ventura.....30/35

Above is what I have in my 1776cc Turbo engine (40 DCOE)

There is more then one model 40 DCOE available.

Fri May 18, 2012 1:41 pm

Great ty HRVW. that will be my starting point. what boost are you pushing & what do you have your timing set at?

Fri May 18, 2012 5:44 pm

I had good luck with F16 emulsion tubes. You might want to start with bigger mains to be safe... Like 170s and work from there.

Sat May 19, 2012 12:17 am

:idea: My carb is set up as a progresive.

200 Air, F11 tubes, 135 main (today changed to 140 main)

210 Air, F20 tubes, 135 main

5-10 lbs boost is enough as engine is strong normally aspirated w/o boost needs.

Engine was 100% NEW parts when built and Balanced.

Idle,jet, start jet, pump jet are critical parts to have CORRECT.

Thu May 24, 2012 12:53 pm

i put in all the new jets in, and now it will only run while i have the choke on

Thu May 24, 2012 2:44 pm

:idea: Re read your specs..........................

Need 1:25 ratios
Adjust carb idle screw untill the throttle plate jusat starts to move
Dial timing light to 26 degrees TOTAL advance and lock dist.
Engine should idle about 1200 RPM...increase idle if needed
Back off both mixture screws
Slowly turn one screw in untill engine falters then back off 3/4 of a turn (starting point)
Repeat with 2nd screw
3/4 of a turn is just a starting point...you may have to work a little to find a happy medium

It will take a little bit of playing with Main/air jets for your area warm/cold/altitude....I'm at sea level.

Advantage I have is a box full of approx 200 main/air jets from my early business days way back when

Thu May 24, 2012 5:41 pm

HRVW i do have 1:25 ratio rockers
I will have to check out my distrib. and see if everything is set correct on that

This afternoon i went to start it and it wouldnt fire. So i decided to remove the carb and check everything. While i had it apart. i cleaned it and checked all the jets for and obstructions. and everything was clean. I put it back on and i will get it to fire for like a sec. i had it backfire with flames shooting out of the carb. It still will only fire if the choke is on.

Thu May 24, 2012 7:30 pm

:idea: What size mains, emulsion tube, air correction are you using?....also ventura size.

Should not be shooting flames out the carb.

Using the 40 DCOE means you have a DRAW thru like mine...but I have a Rajay B25 model.

Double check your Dist cap....I have elect ignition also with no problems at 26 degrees total advance at 3000 RPM.

I cruise the fwy doing 60-65 MPH at 3200- 3400 RPM.

Will bite...what do you mean with choke thing?

Thu May 24, 2012 7:36 pm

The one's I'm familiar with (280zx and Opel Manta) had an "enrichment circuit", same effect as a choke. It was a small lever on the top between the barrels.

Thu May 24, 2012 9:49 pm

:idea: On the Weber that is the cold start that is supposed to connect to a cable by the driver. The DCOE was used on many European cars thus thew choke cable.

I put a small piece of wire thru the lever and tightened it to be in the middle position.

Still need to know your venturas and what jets your running asa per my earlier question.

Fri May 25, 2012 1:03 pm

I have F11 e-tubes in,145 minas, and 205 Air. I'm not sure on the venturis but im thinking either 28 or 30

Sat May 26, 2012 11:48 am

:idea Am not familiar with your Turbo so cannot help on that end since I've got a Rajay.

Carb setting sounds good as a starting point.

Remember the ratio settings.....3 to 1

3 number change with air is 1 change with the mains

I highly reccomend your buying a Weber Carb book as it will explain in good details with photos and exploded parts of most Webers included the DCOE along with carb settings/adjustment etc.

Have had mine since 1979.

Did you try my timimg and carb settings?

Sat May 26, 2012 9:21 pm

:idea: Looking again at your specs.....cam is for a lge drag engine also those 42/37 heads are gulping a lot of air/fuel (what little is fed).

You need smaller valves and milder street cam (Engle 110).

Thats another subject so as it stands with those lge valves more fuel is needed....maybe up too a 175 main and 210 air.

By closing the choke your trying to squeeze as much fuel that those 145 mains are allowing inside. You may have to get more mains above the 145 with steps of 5 ea time. They are maybe $5 a pop but there is only one carb to work with. Air jets 190-215 might be also in order.

Will take a combination to find your niche.

Wed May 30, 2012 5:44 am

Sorry i have not gotten a chance to work on it. I might get a chance this weekend. Summer is here and time is short to work on my hobbies.

Fri Jun 01, 2012 12:26 pm

I was able to work on it last night. I checked for spark, tested the timing, cleaned the carb, and changed the gas. Nothing was working for about 45 min. i was about to give up and decided to try to turn it over one more time. And then it fired and would stay running as long as i had the choke halfway on. It ran strong. Then my wife told me to mow the yard so thats where i had to stop. So i will try to work on it more this weekend to see if i can get it to work without the choke being on.

Fri Jun 01, 2012 3:12 pm

i hear a whip crackin.... :lol: my wife does that too... always ruining my fun! :lol: