Weber jetting, what I've used that works

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Joined: Mon Jun 24, 2013 12:13 am

Weber jetting, what I've used that works

Postby bubbajohnson » Wed Jun 26, 2013 1:43 pm

So I thought I would write up something to help those who are having trouble with their weber carbs and getting them dialed in. One of my biggest gripes through the last few years has been that although all the directions you will find say to look at and write down what jets are in your carbs, NO ONE seems to do this, or share the results. So here is what I’ve had in multiple Weber carbs, on multiple cars, with often vastly different engine set ups. These are all working setups, which were used on street driven cars, all adjustment screws were at or very near weber base settings. These are good functioning settings, which may not work perfectly for you, but can serve as a baseline. YOU still have to do the tuning and checking to make sure your car is in good running order, drive it, read the spark plugs, etc and decide if your carb tune is correct.

#1 32/36 DGEV on internally stock 3TC with approx 230-255k. Stock mechanical fuel pump/lines. Using a Offenhauser dual-port intake, pacesetter 4-1 header and 2.5 inch exhaust with high flow cat.
Primary Fuel Jet: 130
Primary Air Corrector: 165
Primary Idle Jet: 45
Secondary Fuel Jet: 125
Secondary Air Corrector: 150
Secondary Idle Jet: 50
Pump Jet: 50
Emulsion Tubes: F-50
Venturi: 3.5

#2 32/36 DGEV on completely stock 3TC with approx 160-185k miles. Stock mechanical fuel pump and lines.
Primary Fuel Jet: 130
Primary Air Corrector: 165
Primary Idle Jet: 45
Secondary Fuel Jet: 125
Secondary Air Corrector: 150
Secondary Idle Jet: 50
Pump Jet: 50
Emulsion Tubes: F-50
Venturi: 3.5

#3 32/36 DGEV on rebuilt/fresh 2.0L 3TC with fairly large cam, oversized valves, mild port and polished head and high comp 89mm pistons, 4-1 Header with 2.5” exhaust. 3/8 fuel supply and return lines with carter fuel pump and pressure regulator. This engine was dyno tested at 115hp and 112 ft/lbs of torque with a slightly different tune, that showed as being a little lean, so it was re-tuned richer, but not re-dyno’d.
Primary Fuel Jet: 150
Primary Air Corrector: 160
Primary Idle Jet: 70
Secondary Fuel Jet: 145
Secondary Air Corrector: 155
Secondary Idle Jet: 55
Pump Jet: 50
Emulsion Tubes: F-50
Venturi: 3.5

#4 32/36 DGV on 3TC with stock bottom end, oversized valves, an aggressive cam and 4-1 header with 2.5” crush bent exhaust. Stock mechanical fuel pump and lines.
Primary Fuel Jet: 140
Primary Air Corrector: 150
Primary Idle Jet: 55
Secondary Fuel Jet: 150
Secondary Air Corrector: 155
Secondary Idle Jet: 50
Pump Jet: 50
Emulsion Tubes: F-50
Venturi: 3.5

#5 32/36 Weber on very healthy stock 2TC with only 120k miles. Stock Mechanical fuel pump and lines. Factory 4-2-1 header and downpipe with 2” crush bent exhaust.
Primary Fuel Jet: 125
Primary Air Corrector: 145
Primary Idle Jet: 50
Secondary Fuel Jet: 130
Secondary Air Corrector: 150
Secondary Idle Jet: 45
Pump Jet: 50
Emulsion Tubes: F-50
Venturi: 3.5

#6 Single 40mm Weber DCOE 151, on very healthy stock 2TC with 125k miles. Stock mechanical fuel pump and lines. Factory 4-2-1 header and downpipe with 2” crush bent exhaust.
Main Jet: Unknown, they are unstamped, but visually they appear larger then 150 jets, which is the largest I had on hand to compare them to.
Air Corrector: 170
Idle Jet: 50F9
Emulsion Tubes: F11
Choke Tubes: 30mm
Venturis: 4.5

#7 Dual 40mm Weber DCOE 151, on rebuilt/fresh 2.0L 3TC with fairly large cam, oversized valves, mildly port and polished head and high comp 89mm pistons, 4-1 Header with 2.5” exhaust. 3/8 fuel supply and return lines with carter fuel pump and pressure regulator.
Main Jets: 145
Air Correctors: 190
Idle Jets: 55 F9
Emulsion Tubes: F2
Choke Tubes: 36mm
Venturis: 4.5

This is an update to entry #7 on my list.
Thanks to a wideband O2 sensor, discovering my fuel pump was not putting out consistent volume, a float adjustment and a whole lot of drive time, fiddling and tuning I think I have the dual 40's tuned as well as I can with what I know about tuning DCOE's.
Its now running:
Main Jets: 140
Air Correctors: 200
Idle Jets: 60F9
Emulsion Tubes: F2
Choke Tubes: 36mm
Venturis: 4.5
This set up runs GREAT!! Most of the problem with the old "tune" was my fuel issues both with the pump not holding steady because of a slightly loose wire, and I discovered one of my carbs float level was different from the other and they both were set way to high, causing an intermittent bogging issue. Now that both those issues are sorted out and I've logged a good 700+ miles just watching the air/fuel meter and observing then adjusting jets, I'm very happy! The car feels more powerful and responsive then it has at any point with these carbs, I have no random bogging and can drive like as much of a jackass as I want to :cheers:. Just last weekend me and 3 friends loaded up the car with ourselves and maybe 200lbs of gear and took a 240mile trip to the mountains and back. I had no problem holding 70+ up any grade, only shifting to 4th gear every now and again and we got over 20mpg on the trip!! My air/fuel mixture reads about 14-14.5 at idle, so maybe a touch lean, but not bad. 13-13.5:1 at 60-70mph in 5th gear while cruising (Not uphill!). 12-12.5:1 with mild load and on most up hill grades in 4th or 5th gears and 11.5-12:1 under heavy throttle/5000+ rpms right up until it hits my rev limiter at 7000rpm.

Posts: 36
Joined: Mon Jun 24, 2013 12:13 am

Re: Weber jetting, what I've used that works

Postby bubbajohnson » Wed Jun 26, 2013 1:44 pm

Hi all, glad there's a 3tc forum again! Here's my weber jetting info from the old boards, hope it helps some folks :D.

Posts: 375
Joined: Wed Jun 19, 2013 8:35 pm
Location: florida. usa

Re: Weber jetting, what I've used that works

Postby pufito18 » Thu Jun 27, 2013 3:43 am

good info i like it

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Posts: 141
Joined: Sat Jun 22, 2013 12:48 pm
Location: Massachusetts

Re: Weber jetting, what I've used that works

Postby Grumpy3TC » Wed Jul 16, 2014 8:09 pm

Very Good, :ugeek:
MY 3tc is so Grumpy! I feel like eating one or two Rotaries for breakfast today!

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