Tuning Weber DCOE on MGB

[mgbhunter]

I have a 1970 MGB with a single Weber DCOE that seems to be running rich. There is no choke cable connected.I am looking for some help to adjust it. Thanks

[dimefury]

if you live in a nice climate (like here in northern california) you don't need to hook up that choke. you only ever really need a choke when you are trying to cold start the car in cold weather, right?

there are a pair of idle mixture screws near the manifold flange of the carb, one on each barrel of the carb.

is the carb properly jetted for your engine size and rpm range?

[mgbhunter]

Thanks foryour reply-I don't know- I just recently got the car and I don't know much about this carb-I see the idle mixture screws- which way would I turn them to lean it out?

[dimefury]

backing out the screw (turning left, loosening) will make idle mixture richer
screwing in the screw (turning right, tightening) will make idle mixture leaner

if the idle mixture can't be balanced with mixture screw the carb probably isn't properly jetted

there is a good book on weber carbs out there
title- weber carburetors
author- pat braden
publisher- hp books
can probably be found on amazon.com for under $20

hope that helps

[CraigFL]

You can look here:

http://www.piercemanifolds.com/Addendum.htm

[Flash75]

http://www.overstock.com/cgi-bin/d2....prod_id=201195
The Weber Carburetor book costs $12.77 at Overstock.com

Clifton

[mgbhunter]

I checked the idle adjustment screws and both are seated ( lean). 1) how can I find the size of the jets? 2) where can I find the proper size jets for my car? 3) If I change the jets would I have to change emulsion tube(s)? Thanks

[dimefury]

Originally Posted by mgbhunter

I checked the idle adjustment screws and both are seated ( lean). 1) how can I find the size of the jets? 2) where can I find the proper size jets for my car? 3) If I change the jets would I have to change emulsion tube(s)? Thanks

i get most of my weber parts from top end performance, http://www.racetep.com/

thier tech support guys are very helpful, give them a call (phone # is on website) be ready with specifics......what size DCOE (stamped on top), engine size and rpm range, etc.

as for changing the emusion tube....often rather than just buying new jets, you can buy "conversion kits" which come with the correct jets and emulsion tubes which makes it far easier to correctly set up the carb for your application.

hope all that helps.

[irnwoodyhead]

You need to hook up a vacuum gauge to the manifold and check that you a re getting a minimum of 15. set the distributor timing to the highest possible vacuum with your current settings on the carb. Then go to the idle screws and set them up where you like the idle. Higher idle and gas settings ewill keep the engine cooler within reason. recheck your vacuum setting if it dropped then turn the distributor to the highest possible reading hopefully17 or more. The smoothest idle isa dependant on these thre things: idle gas jet setting and timing. Proper air to fuel ratio and subsequent 1.GAS MIleage 2.smooth idle are set with the proer vacuum. Timing guns are good and the timing marks are suggestions but are most likely worn or out of alignment due to many factors valve setting, worn woodruff keys and pullys out of line. Also any clue to the cam size? probably not.

Once the weber is set up to the proper 14:1 air ratio you'll never touch it again.