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Old 08-13-2017
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JonPiz JonPiz is offline
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Default jet help

Just finished the and have a 32/36 DGV. The car ticks over just fine but the engine stalls when accelerating unless the choke is out. Which jets do I need to change?
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Old 08-13-2017
RootesRacer RootesRacer is offline
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Depends an what you mean when you say the "choke is out".

Does this mean no choke or full choke?

If you mean full choke then I'd be inclined to increase the primary main jet but there is more at work than the mains off idle. You also have to contend with the running area "just" beyond idling but before the main kicks in. This is performed by the idle jet and emulsion tube but you also have to consider that the accelerator circuit may also be altering things when throttle is not steady state.
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Old 08-14-2017
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Racer, didn't quite understand the last sentence....
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Old 08-14-2017
Tom H Tom H is offline
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Rooter, I am pretty sure he is referring to the "Power Valve" circuit that applies a momentary squirt of gas when the throttle is initially advanced. If this circuit is not working, even with correct jetting it will not accelerate smoothly.

Tom
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Old 08-14-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by Tom H View Post
Rooter, I am pretty sure he is referring to the "Power Valve" circuit that applies a momentary squirt of gas when the throttle is initially advanced. If this circuit is not working, even with correct jetting it will not accelerate smoothly.

Tom
No, the power valve doesnt give a squirt of fuel when the throttle is opened, this is the function of the accelerator enrichment/pump.

A power valve (when fitted) is a vacuum diaphragm operated main bypass jet that gives some added main fuel when there is no manifold vacuum.

I dont think many if any 32/36 webers have a power valve though all of them have an acceleration enrichment/pump circuit.
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Old 08-14-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by RootesRooter View Post
Racer, didn't quite understand the last sentence....
The idle jet has an emulsion well that richens the static part throttle mixture as a function of the throttle plates passing over the progression holes.

Dynamically however, the acceleration enrichment circuit has to provide some added fuel short term fuel to account for the loss in progression function as the throttle is abruptly opened and the venturi velocity is insufficient to allow the main jet to flow.
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Old 08-14-2017
Tom H Tom H is offline
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RootesRacer said
Quote:
No, the power valve doesnt give a squirt of fuel when the throttle is opened, this is the function of the accelerator enrichment/pump.

A power valve (when fitted) is a vacuum diaphragm operated main bypass jet that gives some added main fuel when there is no manifold vacuum.

I dont think many if any 32/36 webers have a power valve though all of them have an acceleration enrichment/pump circuit.

Thanks for the explanation Racer. I misunderstood the Power Valve operation. I am quite sure that a Weber 32/36 has both a Power Valve (items 14 and 21 on the dwg) and an accelerator pump (items 34 and 36).

http://www.webercarbsdirect.com/v/vs...cs/3236DGV.pdf

Tom
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Old 08-14-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by Tom H View Post
RootesRacer said



Thanks for the explanation Racer. I misunderstood the Power Valve operation. I am quite sure that a Weber 32/36 has both a Power Valve (items 14 and 21 on the dwg) and an accelerator pump (items 34 and 36).

http://www.webercarbsdirect.com/v/vs...cs/3236DGV.pdf

Tom

The 5A which is now the universal aftermarket unit has a power valve.
I think most earlier ones didnt have one.

Its a good thing to have if the engine is jetted right since it can allow you to cruise near 14 AFR and drop to 13 AFR at WOT all with the same mains.
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