Straight thru Holley question

[Rata Road]

I bought this Holley NH yesterday at a swap meet and thought I might clean it up.
I have some new parts on hand, 20 - 25 spray needle etc which states NH 3-3/16 long.
Does this model have different parts or Is this suitable?

Thanks[attachment=1]DSCN5127.JPG[/attachment]

[attachment=1]DSCN5127.JPG[/attachment]

Thanks

[Bruce Compton]

Everything is the same except that all straight through carbs came with the longer throttle and choke arms that can be replaced by the shorter ones if you want to use it on a later T ('24-'27). Both float bowls interchange as well.

[Moxie26]

Kevin ... I agree with Bruce. When you get a chance I'm sure you'll soak that for a few days and then blow through with compressed air and just rebuild like a normal NH, you will be satisfied with the extra performance the straight through will give....... You may want to consider using the high flow intake manifold.

[Rata Road]

Thanks guys.

[J1MGOLDEN]

Look at those two small right side holes in your lower photo.

They are very important to good operation of the carburetor.

They go down to a small puddle area on the other end and the lines have to be clear for an easy start good operation carburetor.

Most of those carburetors have to have the vehicle going over 20 mph to pick up all the gas required without the use of those holes.

Those lines are rather difficult for a "do it yourself" rebuild or overhaul.

Good luck with your home project!

[Rata Road]

Great info James.
I have just had the Carb on my 30 Chev restored and its not right so the restoration shop is coming to my house this Saturday to fault find. I will show him this carb and see what he says.

[Original Smith]

I just put mine on yesterday. The throttle and choke levers are cast.

[VowellArt]

If you do it yourself, please take pictures of all the parts and either send them to me in a PM or post them here. I've done the Simmons Straight Thru, which is basically a Holley Straight, but Simmons made some modest changes to the basic Holley Straight for better performance (supposedly and as I recall the Simmons doesn't have those two small holes on the manifold side) and I'm wondering if the Spray Needle is also the (shorter) same on the Holley Straight as it is with the Simmons.

[Rata Road]

Ok Martynn, I was going to show the Straight Thru to guy from a Carburetor restoration shop that will be here in 2 days to sort my 30 Chev carby.
After Jims comment I was considering to get him to take the Carb and soak properly then rebuild it correctly. If I do I will ask him to record the info you seek. Otherwise if i tackle it myself I will get you all the info you need and post it.

Jim - are these the 2 holes you are referring to?
I notice my UK Ford NH plus another common NH I have here also have those holes, are you saying they are not so important in the other model carbs?

[attachment=1]DSCN5138.JPG[/attachment]

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[Corey Walker]

Those holes are part of the Holley idle circuit with drilled passages replacing the previous pickup tube used in the H1, G and S. The beginning of the passages begins in the mixing chamber and picks up the gas that flows through them at idle.
The H1 and G had a pickup tube that screwed onto a fitting then a passage was drilled that terminated where the 2 holes in the NH are located.
The 1913 model S used a pickup tube soldered to the mixing chamber cover that met with corresponding passenger drilled into the carburetor body.

[Dan Hatch]

If you read the club carb book it tells you how to clean them holes. Tells you the drill number to use. Very informative book.
I install little set screws in place of the brass plugs. Just be sure to not block passages with them.

[MarkS]

The drilled holes have another advantage. I have a Holly G that has the separate pickup tube and nut. The first time I removed the manifolds from my car I found the nut in #2 intake valve chamber and the tube in #3 intake valve chamber. Fortunately, there apparently wasn’t enough flow to suck them up paste the valves!

And yes, it was very hard to start!

[Jerry VanOoteghem]

Ok Martynn, I was going to show the Straight Thru to guy from a Carburetor restoration shop that will be here in 2 days to sort my 30 Chev carby.
After Jims comment I was considering to get him to take the Carb and soak properly then rebuild it correctly. If I do I will ask him to record the info you seek. Otherwise if i tackle it myself I will get you all the info you need and post it.

Jim - are these the 2 holes you are referring to?
I notice my UK Ford NH plus another common NH I have here also have those holes, are you saying they are not so important in the other model carbs?

DSCN5138.JPG

DSCN5149.JPG

If I may, those 2 holes are very important for either carburetor. More than just soaking, they need to be cleared with the proper size drill. The holes they intersect with also need to be drilled out, which requires removing and replacing a couple of brass plugs. Hoping you & Jim will pardon my jumping in on this.

[Rata Road]

So let me get this straight, are you saying the single hole on the face plate which bolts to the manifold needs to be drilled out to enable you to access and drill clear the tube which is attached to the 2 internal holes pictured about?

Is that why the single hole on this UK made Model T Ford Zephyr NH looks like a brass plug?

Thanks

[attachment=0]Brass plug.JPG[/attachment]

[Jerry VanOoteghem]

So let me get this straight, are you saying the single hole on the face plate which bolts to the manifold needs to be drilled out to enable you to access and drill clear the tube which is attached to the 2 internal holes pictured about?

Is that why the single hole on this UK made Model T Ford Zephyr NH looks like a brass plug?

Thanks

Brass plug.JPG

Yes, correct. See Corey Walker's first photo, above. He demonstrates the course of the holes involved by inserting brass rods in them. The entry point of each hole will be identified by a brass plug.

[Rata Road]

The Carb restoration shop didn't know anything about the holes or clearing the tube so I didn't give him the carb.
Other than getting the club Carb book I trying myself, any suggestions on who can rebuild this correctly?

Thanks

[Moxie26]

Kevin... Don't lose confidence in yourself, you're getting the carburetor book and you have access to parts and I'm sure you can do it yourself. .....I would not drill out any of the plugs, but I would suggest finding someone that has laser cleaning facilities to clean up the core and fuel bowl, and afterwards wouldn't hurt to leave soaking in carburetor cleaner for a couple days to a week. Compressed air can clean out passages. After reassembly if you're not satisfied with it compared to the other NH carbs you have, then a professional can be found... But don't lose interest in what you can do yourself. I'm sure there's a few here on the forum that can verbally help..... By the way, the carburetor you have is a later production straight through since the name tag NH is covering the fuel bowl vent instead of having the screw in vent on the first run carbs...... As far as local help, is there any one in your area that have Model T's?

[RecklessKelly]

I brought an ultrasonic cleaner and motorcycle carb ultrasonic solution on amazon. Ive done a few carbs with it including my NH. The unit has a heater that gets the solution hot. I use wire strands to chase the passage holes and jet holes. Compressed air and a final blast of carb spray.

[Rata Road]

Thanks Guys,
I had a look at the ultrasonic cleaners, working out which one would hold a Carb is the question. What model/size did you use ?

[RecklessKelly]

Vevor from amazon. The inside is 9.5 x 4.5 x 4" deep.

[J1MGOLDEN]

Those are made in China now too.

[JTT3]

Send it to Corey Walker, you’ll get a carb that’s rebuilt well and tested on an engine.

[Rata Road]

Thanks, Ill look him up.