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5 Posts
Discussion Starter · #1 ·
Can anybody recommend what size jets I should fit in my beach buggy's Twin Weber 36IDF carbs. I currently have a 130 main but my bug isn't running particularly well once she gets going.

I’m running a 1,641cc engine (Engine Number: AS61xxxx) with the following spec:
Mahle 87mm B + P
German 69mm crank balanced with 311 B rods + 12V 200mm Flywheel
Engle V26 cam - 297 duration 0.335” lift at cam
Manton steel pushrods
Magnum Straight cut gears
Scat 1:4:1 rockers
Type 3 F.I. 040 cylinder heads, stainless valves, heavily ported with matching manifolds
New valve guides cut down to suit cam and profiled at the ends
Berg Heavy Duty Valve Springs
Bug Pack hardened collets + steel caps
Twin 36 IDF Webers 32mm Venturis Berg linkage
Facet electric fuel pump
SSP Weber style Fuel pump pressure regulator
Bosch 009 distributor with Petronix Ignitor kit
Bosch Blue Coil

Looking forward to your responses.


1,028 Posts
It's not just about the mains.
What size:
. Air
. Idle
. Pump

jets do you have fitted.

32mm vents may be a little too big for a 1641, others may disagree.
OK for flat out top end performance, but not so good for low end grunt and torque - 28, 30, 32mm vents are the usual choice, the 2mm increase makes a considerable / noticible difference on engine performance.

Need to balance engine size/cc, with carb size (36/40/44), with venturi size (28/30/32), with jet sizes (mains, air, idle, pump), with desired engine use (drivability vs flat out speed).

You can usually rough it out, but it is hard to beat a rolling road tune and carb set up.

I see you are Sussex based have you join us VVVVVVVVVV a few of the guys in the club have twin carbs and have used localish rolling roads.

Help! I'm trapped in here
20,698 Posts
According to my list:
Vents - 30
main jet 140
emulsion F11
air correction 210
idle jet 55
pump jet 50
needle valve 200

This is a safe starting point for final sevlection by RR tuning.

676 Posts
Eurocarb recommended that I use the following jets in my IDFs for a 1641:

Idle: 55
Pump jet: 50
Emulsion: F11
Air corrector: 180
Main: 115
Vents: 28mm


exactly what ive got for my 1600.
just got these, from here;
and my f11's;
not a cheap job so get it close as possible.
and yes they do fit (italian 36 idfs).
cheaper than eurocarb!

5 Posts
Discussion Starter · #7 ·
Thanks to all those that have given input.

I have now consulted Eurocarb and have been advised the best set-up based on my engine spec is:

Vents: 30mm
Main Jet: 125
Emulsion F11
Air Correction 180
idle Jet 55
needle valve 175

I have also made the same enquiry to Laurie Pettitt, and once I have this feedback I will make my final decision.

Once I have installed the new set-up I will update this post so others can benefit and make their own informed decision.

Thanks again for your input.

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