How do you set up twin carbs?

Let the engine warm up and set the ignition timing. Then, on each carb, wind the idle mixture screw in until the engine starts to slow down, then wind it slowly back out until it starts to speed up again. Leave it there. Adjust the idle speed screws the same amount on each carb until the idle speed is right.

How do twin SU carbs work?

SU carburettors featured a variable venturi controlled by a piston. Since the needle is tapered, as it rises and falls it opens and closes the opening in the jet, regulating the passage of fuel, so the movement of the piston controls the amount of fuel delivered, depending on engine demand.

How does a Weber carb work?

A Weber carburetion system will respond to the gas pedal just like a fuel injection unit, and that’s because both have short, isolated intake runners with a small mass of fuel/air to move when you crack the throttle. Throttle response is all about air speed, or “Velocity”.

How does the Weber carburetor work?

The Weber Carburetor is a sequentially timed device to the motor like the distributor. Time taken in the setup will provide more fun later. If you should need to call REDLINE WEBER for technical assistance we will need to know your final settings to help. Technical assistance is free for the first 60 days of purchase.

What size velocity stacks do I need for my smallblock Weber?

Pictured here are two of our smallblock Chevy IDF units fitted with 4-inch and 6-inch velocity stacks to show how different they can look just by the length of the stacks. These can also be built with the short 1-inch stacks to fit under the hood of an early Corvette, making the IDF system the most versatile Weber configuration available.

What size carburetors does a Chevy big block have?

The Bigblock Chevrolet IDF system is shown here exactly as shipped without any special finishes. The IDF system fits oval port heads only. The IDF units are both compact and extremely versatile, offering you the choice of 44mm or 48mm carburetors.

What is the best book for tuning carbs?

The Weber Factory Tuning manual and Haynes Weber Book has all the good technical information already written. These 2 volumes are the backyard mechanics guide to the basics you need to know to make your carbs run right….