Last week I switched out the Holley NH that was installed on my 11 touring to a Holley G and noticed it takes more "cranks" to get Carl started. With the NH he'd fire up in less then a crank, with the G I'm having to crank at least four times to get him going. Normally I choke the NH one crank. I've done one to three cranks choking the G and still takes me four cranks to get him going.
How do you have the needle set?
Needle position may help, float level is most important. The optimal "puddle" to supply the idle tube needs to be set correctly via the float level. I put a "G" on my '13, used to run a "G" on the T I had years ago. Good carb, I've never had trouble with them.
James asks the first important question: could your needle be set a bit lean?
Is this a "known to run well" carburettor? Is it rebuilt? Is the float adjusted correctly? Is the strangling tube adjusted correctly? The Service Bulletin Essentials book has very good instructions on proper adjustments of the Holley G. It IS a good carburettor. Ford used it for about six years during which time sales climbed, something that would not have occurred if the Model T was burdened with a "hard to start" carb.
Carb is NOS I believe, float rotted away (replaced float) but everything else nice and clean. Didn't adjust anything just threw a bowl gasket on and install. Car runs very well with it on, just doesn't start that easy.
I also suspect float level adjustment or needle setting needs to be tuned in........Should start easier than that. And run real well.
I ran G for many years and it ran great, but I also had a hard time starting it, especially when it was very warm. I swapped to a Stromberg OF and have no problems. My G carb was not actually rebuilt, I had just cleaned it as well as I could and set the levels. I ran it on my '11 for awhile; with the original '11 JB coils I could not start it on mag, but with the later coils I could. Are you using a battery or mag when you start it?
Battery, then switch to mag for run.
The new floats displace more fuel than the original ones, effectively lowering the fuel level in the bowl. You need to assemble the carburetor minus the top with the needle and adjust the fuel level so there is a pool of fuel in the depression in the bottom of the inlet. If you get it too high it will drip fuel out the overflow so it needs to be just above the hole. That's why the piece is made that way. That gives it fuel to start. If the fuel level is too low they will still run fine but be nearly impossible to start. If it is too high they will drip fuel and also tend to slobber when the engine first starts because there is too much fuel available.
You also have to be absolutely sure the top cover fits the body tightly. Many of them are so bent and warped they do not seal. When the choke is pulled shutting off the air flow they will pull air around the top cover and not draw fuel to start.
Holley G = best of all Ford supplied carburetors from 14 - 27. Expensive and time consuming to make, all later versions were cheaper.
Stan... I assume this may explain why the Holley 2-screw (Model S) can be so stinkin' hard to start as well??
That is at least part of it. Part of the solution to a good starting and running 2 screw is to replace the little brass "strangling tube" (venturi) with a machined one that forces the air to pass much closer to the fuel puddle in the bottom of the chamber.
Also, the cover plates on them are notorious for warping and leaking air, too.
They run IMHO better than people give them credit for. Here is one I just sent off to Canada last month. They are beautiful carbs with that brass bowl and if set up right they run very well.
Look in "The Book" which shows a float checking set-up from Hugo, and the dimensions for fabricating a little gauge to check the puddle depth. Like Stan says, you leave the top off and look down in the carb while fuel flows to see where it is in the puddle. Also use gasoline, not water to check level. It is time consuming, but isn't everything else with a T?
Please give more description for float and puddle setting please.
Other than the choke lever and the materials used, is there any difference between the bronze and cast iron G?
Brass one dont rust
Good question Steve. :-)
Philip asks about the puddle depth... :-) Thank you for asking Philip. :-) Would you fellas be so kind to share?
The Ford diagram in the service bulletin from 1920 shows the "cup" to be filled a little bit more than 1/3 full.
Almost half full but not quite. Ford tool 24-Z-2393 would do it.
The cup on my iron G is about .270" deep so that tells me the puddle should be around 1/8" deep. I figured almost .135" initially.
But I could be very wrong. My idle tube falls within specs.
I think I have a carb "The Book" book here but I haven't seen it for years and I didn't have a G at that time anyway so it's lost until I call the museum for another copy.
I don't have Hugo's dimensions of the puddle depth tool.
Wishing for more accurate info myself. Been messin' with a 3 screw iron G for awhile.
I dunno about the "book" as I haven't looked in it for years but in my experience the critical thing is to have fuel in the depression in the inlet an 1/8 of an inch or so deep when level on the bench. Another thing to check is that the idle tube end is submerged in the fuel. It needs to set right on the bottom of the depression -- just off to the side enough to allow the needle to pass by it.
The float height needs to be set for the material of the float being used as well as the size. The new Holley G floats are larger than the originals - therefore they displace more fuel in the bowl and close the needle valve sooner. In other words, the thicker float contacts the fuel coming in to the bowl earlier and closes the needle valve at a lower fuel level than a thinner float.
You have to adjust it to get the fuel in the puddle area. It is also important on the G that the float be level when closed. The bowl is quite large compared to many others and the float will close the needle too soon if the float is not level or if the carburetor is not level on the engine.
That is probably the reason all the later carbs are smaller in diameter in the bowl area.
If memory serves me correctly I think the idle tube may even have a little crease in the bottom to allow the needle to pass by. I made a little brass gauge like that shown in figure 224 to check the depth. The Model T Ford Owner by Fahnstock on pp. 194 says the depth of the fuel should be between 1/16 and 1/8 below the rim of the cup. The gauge shown has tips reflecting those dimensions and is shown on pp. 195. Hope this helps you G owners.
One of the accessory items that used to be commercially produced for the T carbs was an adjustable idle jet, which replaced the plug on the side of the G carb that gives access to the idle tube carrier. One version had just an adjustment to the fuel supply - which probably worked quite well - another I have seen had an air bleeder hole which would have allowed the air flow to increase to the idle jet ahead of the throttle plate and to add air to the mixture supplying that jet. I would guess they worked quite well. One of the things I have seen when working on Holly G's that don't run well is the passage from the plug to the jet ahead of the throttle plate was not clean, causing it to not supply fuel at idle. Like all carbs, the passages have to be clean.
Philip, if wishing for reference, the bottom of the flattened idle tube is supposed to be .011"-.018" above the "floor" of the plate/"cup".
"After the low speed tube has been tightened in its position by means of the pack nut the lower end should rest against the shoulder of the body above the plate and should be .011 to .018 above the surface of the plate."
By gum. Now I see the pic I posted myself more clearly. The short leg of the "puddle" gauge 24-Z-2393 rests on the TOP of the 4473A (nomenclature) with the two raised tangs.
Very interesting notion about the large bowl and float. Makes sense. If parked in a very hilly area, the G might've been a bugger to start.
Low idle tube height combined with relatively high fuel level in the cup/above the plate allows for some variation from perfectly level for the carb to work as intended with out it going potty on the ground.
Pictures of G tools show a thin wire with a slight crook on one end to slip down inside the bowl to check the depth of the tube. Had a little loop on the other end for finger.
I used a couple different strands of copper wire as my idle tube height gauges. :-)