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Holley G versus NH
Posted: Sat Oct 09, 2021 9:28 pm
by Oldav8tor
I wonder if anyone has any experience comparing the operation and performance of a Holley G versus a Holley NH carb? I hear many people say that the NH is one of the best carbs ever made for the T while others praise the G. I have a nice G on my '17 and just bought an NH to try. I'm curious what to expect. Note, both carbs are Russ Potter rebuilds.
Re: Holley G versus NH
Posted: Sat Oct 09, 2021 11:11 pm
by dr1960
My '15 T had an NH on it when i bought it. Car ran great with it. I purchased a rebuilt Holly G from Corey Walker to put on after my engine rebuild since i heard the '15 would have likely had a G originally. The G is a smooth running carb and the car starts very easy. Once i got the fuel mixture set, i have not had to touch it. I like the G so much i have not put the NH back on to compare. I have about 300 miles on it since the engine rebuild. Some say the NH gives you a little more top end, but i don't really know. Just my experience.
Re: Holley G versus NH
Posted: Sat Oct 09, 2021 11:25 pm
by DHort
Tim
A couple of years ago there was an article about someone who tested about 10 carburetors to find which one was best and which one was worst. I hope someone else sees this this tells you when the article was posted. I do not remember if it was Vintage ford or Model T times.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 1:41 am
by ModelTWoods
I think most people who have tried both, particularly if the NH was a "straight through" NH, would agree that, at least performance wise, the straight through NH is the best, however I am one who has run G's on a 13, a 16, and even a 26 and swear that I can't tell much difference between a G and an NH swayback.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 11:53 am
by speedytinc
Flow tests were done on a variety of T carbs. Straight thru: 31cfm. Sway back: 29cfm. The G was a bit less. Only under the highest max flow conditions could you notice. The sway back is the simplest unit. The G is a fine carb, A bit more complex maybe? Critical internal pick up tube. Real easy to get the fuel level perfect. Maybe better @ fuel mixing because of the air path?
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 12:03 pm
by NealW
I have a Corey Walker rebuilt G on our 15 runabout and a Snyder's rebuilt NH on our 21 that we just sold, and both are great carburetors. My observation is that the G is easier to flood though, so you need to be be careful about priming. The NH takes two quarter turn cranks to prime and the car starts right up. Do the same on the G in mild temps and it can flood. I usually only do one quarter turn prime on the G.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 12:31 pm
by speedytinc
NealW wrote: ↑Sun Oct 10, 2021 12:03 pm
I have a Corey Walker rebuilt G on our 15 runabout and a Snyder's rebuilt NH on our 21 that we just sold, and both are great carburetors. My observation is that the G is easier to flood though, so you need to be be careful about priming. The NH takes two quarter turn cranks to prime and the car starts right up. Do the same on the G in mild temps and it can flood. I usually only do one quarter turn prime on the G.
The fuel level in the NH may not be perfect. Too low. My nh takes 1/4 choke pull & never needs richening to start or any adjusting for idle & hi speed.
Yes, untill I figured it out, It was harder to start due to too much choke.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 4:41 pm
by Oldav8tor
I haven't tried my new swayback NH yet. My G is pretty much a set and forget carb. I don't have to choke it or temporarily enrich the mixture to start and I usually start on Mag. It runs great, my only complaint is I've had the engine stutter going up a steep hill (5 gallons in my under seat tank) and once on the way to the gas station with about 2 gallons left. I wonder if it is a fuel pressure issue based upon the relative height of the fuel in the tank compared to the carb. Scott Conger makes a valve for the NH that is supposed to alleviate some of the fuel-flow issues which is why I was interested in trying one.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 4:59 pm
by old_charley
Here's some carburetor and manifold flow info. Hopefully we're not running afoul of copyright law.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 5:37 pm
by troutjohn
I put Holley Gs on my 1912 and 1913 replacing Holley NHs. I like the Holly Gs much better. Much easier cranking starting, better power accelerating and better power on hills. I have since sold the NHs.
John
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 6:54 pm
by speedytinc
Oldav8tor wrote: ↑Sun Oct 10, 2021 4:41 pm
I haven't tried my new swayback NH yet. My G is pretty much a set and forget carb. I don't have to choke it or temporarily enrich the mixture to start and I usually start on Mag. It runs great, my only complaint is I've had the engine stutter going up a steep hill (5 gallons in my under seat tank) and once on the way to the gas station with about 2 gallons left. I wonder if it is a fuel pressure issue based upon the relative height of the fuel in the tank compared to the carb. Scott Conger makes a valve for the NH that is supposed to alleviate some of the fuel-flow issues which is why I was interested in trying one.
If it's an unmodified viaton, it's too restricted. Get Scott's hi flow unit.
Re: Holley G versus NH
Posted: Sun Oct 10, 2021 6:59 pm
by speedytinc
troutjohn wrote: ↑Sun Oct 10, 2021 5:37 pm
I put Holley Gs on my 1912 and 1913 replacing Holley NHs. I like the Holly Gs much better. Much easier cranking starting, better power accelerating and better power on hills. I have since sold the NHs.
John
Again, There is some fine tuning to get the fuel level correct on a NH. One could & does get luckey with the initial float dimensional setting, but I have found fine tuning the norm to go from good enough to excellent.