ClassicCar

dougson

Do the Carter WA-1 carbs on the twin-H setup produce much vacuum? I have the vacuum advance hooked to the front carb and there is practically no diference with the advance plumbed in or removed, maybe a few degrees. A have two vacuum gauges set up and I'm getting 20" at idle whether the advance is connected or not. Does the advance come off ported vacuum? If true, there must be a reason for this because manifold vacuum would produce a lot more vacuum (it seems) at idle.

Park_W

Vacuum for the advance is indeed off a port that's a little above the throttle plate when in idle ... you have to be a little off idle to get vacuum to the distributor. They didn't want any vac advance at idle. Also note that the Hudson distributors don't provide nearly the amount of vacuum advance that's seen on other cars. You can look at the spec's and see that the vac advance is very modest, so you're not going to see ten degrees or anything close.

walts garage-53 · walts garage-53 September 2011 Posts: 1,470Platinum Member

Vacuum advance does not work at idle, only when you increase the engine. Timing set at idle, long mark on flywheel. Disconnect the vacuum line and race engine and mark should raise about 2 inches. Connect vacuum line and race engine and mark should go clear to the top of the opening in the motor plate. Total advance with spark disconnected is 9 degrees and with it hooked up vacuum advance goes 4 more degrees for a total of13 degrees. If vacuum does not increase timing, check the vacuum advance unit to see if it can hold vacuum, if not must be replaced. Walt.

Sarah Young

Can you explain what the purpose of the screw/rod in the pictures are? (Pointed at with screwdriver.)

[attachment=12025]CarterWA1Carb1.jpg[/attachment]

[attachment=12026]CarterWA1Carb2.jpg[/attachment]

walts garage-53 · walts garage-53 September 2011 Posts: 1,470Platinum Member

If you mean the shinning round head with the screw driver slot, that has a gasket on it, and must be tight, as the idle jet is under it. Walt.

GrimGreaser

Does it 'fit' into a matching jet in the bowl? Kinda looks like the needle of an adjustable main jet.

walts garage-53 · walts garage-53 September 2011 Posts: 1,470Platinum Member

It's a hollow tube the screws into the main body with the correct size hole for the car it's on. All WA-1's take a different size hole. They have numbers stamped on the top, like 53-54 Jets take number 11-169s, 50 to 54 Wasp and Pacemaker take number 11-165s. What is the carter carb number you took the picture of and what engine does it go on? Walt.

GrimGreaser

I don't think she's pointing at the idle jet. I just rebuilt my Twin H WA-1's, I don't recall whats pointed out as being on mine. I'm not familiar with any other WA-1 configurations however.

It looks like it sits over the pump inlet hole, between the idle jet well and the pump well. With it being pointed, it kinda looks like the needle of an adustable jet set-up like on Strombergs, ect.

Geoff C., N.Z.

This is an adjustable jet that is used on replacement Carter WA1 carburettors for Universal use. Instead of specific metering rods it uses an adjustable needle. If your car is running too lean you wind it up, and too rich, wind it down. You can enable or disable the vacuum piston, by unhooking the torsion spring, whichever makes the car go better.

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