Carburator Control Rod for Holly G vs NH

[troutjohn]

I have an 1911 and 1912 and just changed them from Holly NH carbs to Holly Gs. I seems that the carburetor control rods are a little bit to short to get a low idle. Both cars are the same, maybe short by 1/8". My control rods are adjustable with thread on the steering side and I have them out as far as I dare. Rods are fairly straight so no more to gain there. Do Holly Gs take a longer rod than a NH? I've seen a mention of this in several threads. Does anyone have them or do I have to make them? Any other solution or something I'm missing? Other than a little higher idle the Gs are excellent and seem better than the NHs. Many thanks in advance, John

[speedytinc]

I believe venders list the g & nh throttle shaft/arms as interchangeable.(early nh 20-22)
23-27 have a shorter arm. So the arms on both your carbs should be the same length.(shaft to hole) Your nh arm is likely later type. Can be compensated for by bending the arm a bit toward the block. Or replace with the proper early lever.

[speedytinc]

I believe venders list the g & nh throttle shaft/arms as interchangeable.(early nh 20-22)
23-27 have a shorter arm. So the arms on both your carbs should be the same length.(shaft to hole) Your nh arm is likely later type. Can be compensated for by bending the arm a bit toward the block. Or replace with the proper early lever.

Sorry, I went the wrong direction with your carb change.
The arm on your G & 20 NH originally was cast brass. The replacement arm(early style) is stamped sheet.
The arm on your G's can be bent toward the block ,gently, to give you a full idle stop. Shouldnt be necessary if both correct levers are pinned tight correctly and your throttle rod is of the correct original length with no extra slop. Are they short repop throttle rods? Consider making a longer one.

[troutjohn]

Hi Speedy, thanks for the reply. I think they are original rods. They are straight and appear to be old. The repros in Lang's have bends. I'm afraid to try to bend the carburetor arms. I called Langs to see how long a rod they might have and they are going to make me slightly longer rods! Lang's is the best! John

[Hudson29]

I called Langs to see how long a rod they might have and they are going to make me slightly longer rods! Lang's is the best! John

That is an example of a good outfit!

Paul

[KWTownsend]

John-
If the carburetor rods on your 1911 and 1912 cars are original, one end will have an L shaped bend and the other end will have a #12-32 threaded end. A female threaded L shaped end screws onto the rod and allows for some adjustment to make it a little shorter or a little longer. Your timer rod would have a similar set up with a swivel screwed on the end of the spark rod.

I believe the threaded end of the throttle rod is supposed to be on the steering column side, but it makes for an easier adjustment if it is on the carburetor side.

: ^ )

Keith

[troutjohn]

Hi Keith, thank for your reply and picture. That is the rod that I have. It is fine for the Holly NH carb but a 1/4" - 3/8" short for the Holly Gs. I'm at about the end of the thread on the rod. I'm looking forward to the longer rods from Lang's. I do love the Holly Gs - easier starting, more power up hills and faster, and of course looks great.

John

[Scott_Conger]

The G is a great carb, but the only reason it's out-pulling your NH on hills is because you very likely don't have a properly dimensioned float valve in the NH and the car is starving for fuel. That can be fixed, but if you're happy with the G then I wouldn't suggest replacing it. At the very least it is more period correct though misses by a year or two.

[speedytinc]

The G is a great carb, but the only reason it's out-pulling your NH on hills is because you very likely don't have a properly dimensioned float valve in the NH and the car is starving for fuel. That can be fixed, but if you're happy with the G then I wouldn't suggest replacing it. At the very least it is more period correct though misses by a year or two.

Scott beat me on this one. A NH flows more air than a G & will out perform it. Thats why they are so popular. NH float specs are a starting point & need to be adjusted for a precise fuel level for good hi speed & idle mixture @ the same time without messing with the mixture needle. Current, unmodified needle/seats can restrict the fuel flow to a lean condition when you need it for speed or hill climbing. You had a bad NH.
What i do like about the G, is that the fuel level is viewed and adjusted for by where the fuel sits in the bowl of the jet. No trial & error, just remove the needle top plate. Adjust the float as needed on the bench. You know its good to go before you mount it.

[KWTownsend]

John,
A short section of 12-32 coupling nut and corresponding section of all thread rod would take care of your problem.
: ^ )