Converting Holley NH swivel top to nonswivel NH?

[NealW]

Our 21 touring has a Holley NH swivel top carburetor. The carb is in good shape, but since the swivel top was originally for 1925-26 cars with taller firewalls, the adjusting rod makes too large of an angle at the U-joint to go through the shorter 21 firewall, making it very difficult to adjust the mixture while in the car.

Does anyone know if I can convert the carb to a nonswivel version by removing the current swivel spray needle and clamp nut and replacing them with these from Langs?

Adjusting needle clamp nut for Holley NH:
https://www.modeltford.com/item/6208.aspx

NH Spray needle assembly:
https://www.modeltford.com/item/6213.aspx

Thanks,

Neal

[Original Smith]

Do it! An NH will accept either.

[Mark Gregush]

Not necessarily, the threads for the spray needle are in the nut for the 25 up NH's. Your carb body may not have threads in it for the earlier spray needle. Check.

[NealW]

Not necessarily, the threads for the spray needle are in the nut for the 25 up NH's. Your carb body may not have threads in it for the earlier spray needle. Check.

Mark,

Here's a picture of the top of my NH carb. The clamp nut threads into the carb body like the nut for nonswivel top. Is this what you were talking about?

thanks,

Neal

[Mark Gregush]

Pull the spray needle and nut to see. The earlier carb clamp nut does not have threads in it like the later one you have. The threads the spray needle screw into in the earlier carbs are in the carb itself, not the nut. Your carb body may have the threads, that is why I said to take a look see.

[DHort]

I never have to adjust either of my carbs in both cars. Wondering why you have to adjust yours so often? You should be able to set it and leave it there. Just trying to save you some hassle.

[Corey Walker]

I’ve never seen one without threads in the carburetor body regardless off which needle was on it. The later needle threads only into the nut and not the body but the threads are still in there or you can make a T top to a swivel top also but you have to replace the needle and nut.
The ones made in 1926 for the cowl mounted tank have a slightly larger float to compensate for added fuel pressure but the bodies are the same.

[NealW]

I’ve never seen one without threads in the carburetor body regardless off which needle was on it.

Before Corey posted this, I took out the needle and nut, and yes, the carb body was threaded...

I never have to adjust either of my carbs in both cars. Wondering why you have to adjust yours so often? You should be able to set it and leave it there. Just trying to save you some hassle.

I don't adjust it much either, but during my first drive in April this year, it was acting like it was running a bit rich and I tried using the knob while driving, but it was really hard to turn, leading to my original reason for the post!

[NealW]

I appreciate the feedback. I may just leave it alone, but I do have a question about the actual installation as it came on the car when I bought it. The picture shows U joint at the top of the carb, but then there's a second U joint to get the adjusting rod around the intake heat pipe, where the rod then goes up to the hole in the metal firewall.

All that zig zagging is what makes it hard to turn from inside the car. Is that how the installation is on a 25-27 car, or is this someone's attempt to make it work on this car?

Thanks,

Neal

[RajoRacer]

Rube Goldgerg attempt ! If you are going to utilize the swivel type adjuster, one needs to also use the later style hot air pipe that has a flattened area for the adjustment rod to clear.

[RajoRacer]

I also see that you stated a '21 BUT it has been updated to a steel firewall - original would have been wood - it sure appears as though the adjuster rod is not coming out of the correct slot for proper alignment !

[Scott_Conger]

Your actual problem is two-fold:

1. the carb stove (heat pipe) is not snuggled up against the exhaust manifold; it is sticking far too far off of it.
2. the kludged double-universal is made to go around it and will never work properly

with the carb stove properly positioned, the correct adjuster sans-swivel will JUST go past the stove (or maybe rub on it, mox nix).

You need to buy:
1. proper needle
2. proper adjuster rod
3. proper needle clamp nut

problem solved and life is good

[RajoRacer]

Here's a quick hot air pipe 101 - I'm not the encyclopedia so let's remember that - far left is around 1912 + /note the crimped edges, next is '13 to later teens, 3rd is into the later teens w/old style clamps, 4th is new style clamps (mounted in reverse of original) - note mount and last is new style clamp AND swivel adjuster - just my own observation. I have close-ups if any interest.

[Scott_Conger]

I'll add one more thing to my post, and that is that I suspect that your hot air pipe is a reproduction. Every reproduction pipe should come equipped with a set of tin-snips, because it needs it. Without significant massaging with tin-snips, every reproduction hot air pipe fits exactly like yours does right now.

[RajoRacer]

Astute observation on Scott's part & to add to Scott's post - all repros I've seen have an open mounting point - originals were closed like shown below on the left.

[NealW]

Astute observation on Scott's part & to add to Scott's post - all repros I've seen have an open mounting point - originals were closed like shown below on the left.

Steve,

The heat pipe on our 21 is the circled one in the picture below. It does not have an opening, so perhaps is original make from years ago. The unknown installer or restorer apparently decided to add a second U joint to get around it. Regarding the steel firewall, they were available in 1923? and were backwards compatible for post 1916 cars. I'm glad that the car has one, as it seems more durable than a plywood one.

Scott is correct that the holes in the repro ones, at least the one that I installed on our 15 restoration, needed reworking to get the hole opened enough some to allow the clamp to fit correctly.

I may just order a new heat pipe with a hole when I get a needle, clamp nut and new rod and at least make it correct for the year. Having it work better would be nice too!

[TRDxB2]

Your actual problem is two-fold:
1. the carb stove (heat pipe) is not snuggled up against the exhaust manifold; it is sticking far too far off of it.
with the carb stove properly positioned, the correct adjuster sans-swivel will JUST go past the stove (or maybe rub on it, mox nix).

Easy to see what your saying the fix is

[DanTreace]

August 1925

IMG_3504 (573x580).jpg (112.88 KiB) Viewed 5850 times

The new adjustment needs the correct heat pipe, with a recess to allow the rod to clear.

That is the way of the Improved Car, but sure is nice to use the combo rod on early Ts, esp. when you add a starter, so dash choke is handy, did that 'upgrade' to the Faux '09 runabout.

Engine compartment (2).jpg (190.36 KiB) Viewed 5850 times

[NealW]

My new heat pipe, mixture rod, nonswivel needle and nut came in the mail today, so time to swap out the parts. As expected, I needed to do some filing on the hole in the heat pipe to get the exhaust clamp to fit. I also needed to slot the hole in my firewall a bit more to get the triangle shaped end of the rod to fit through.

One thing that surprised me a bit was how much my mixture setting changed. I initially set the needle to about the same as the one I removed, but I had a hard time starting it and keeping it running well. It was too lean, requiring about 1/4 more turn rich for it to idle and run well. The shape of the needle was apparently different.

Anyway, I can now finally adjust the mixture from inside of the car, and the car is now set up correctly for its year.

[Scott_Conger]

Congratulations, Neal. Job well done.

I sure wish the repro adjusting rods were made correctly with the correct size handle, don't you?

In retrospect, isn't it pretty funny all the trouble the last guy went to to solve that problem?

[NealW]

Yes it would be nice if the handle was the right size, but I had read that they were too wide, so I expected to do the rework.

Who knows why the original restorer did it that way. I didn't know any better when I first got this T. I was a bit surprised how bad it worked, not realizing that it wasn't how "Henry" really made it!

It is interesting to see the cost cutting measures Ford did over the years. The one piece bent mixture rod compared to the mixture rod with a separate brass knob on our 15 runabout.

[Original Smith]

Take a look in a '26-7 parts book under late carburetor adjusting rods. I believe there are seven different lengths! I think the one on my 1925 is 23".