Carburetor Help

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Model T Ford Forum: Forum 2015: Carburetor Help
Top of pagePrevious messageNext messageBottom of page Link to this message  By henry h on Sunday, March 22, 2015 - 02:29 pm:

Trying to start for the 1st time - on adding gas, find i have a leak coming from the engine side of the carb on the protrusion just ahead of the choke pivot - see arrow.

What type of carb is this?

What would be missing that would cause a large leak - there seems to be a hole?

I can pull it out, but wanted to know what's going on.

PS: Since the pic was taken, a new cutout was installed on the starter.

Thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donald Conklin on Sunday, March 22, 2015 - 02:48 pm:

Sounds like gas coming out of the vent. The needle is not seating for some reason. (dirt in the needle and seat, float has gas in it or a bad needle and seat) Before you pull it apart try tapping the carb with a hammer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, March 22, 2015 - 03:34 pm:

One of my T's came with a carburetor that had slept with the fishes. It had rust holes through the bowl. But usually gas running out is, as Donald says, a stuck or bad needle valve.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, March 22, 2015 - 04:44 pm:

You never know when a Model T carburetor is going to start leaking. I agree with the above either a bad needle or seat, wrong adjustment of the float or float full of gasoline or dirt in the needle valve. Dirt can come at any unexpected time or the float can stick. On more modern vehicles with the gas tank low in the back of the car and a fuel pump operating to supply gas to the carb or fuel injectors, you are less likely to notice a leak because when the engine is not running, the fuel pump stops working.


Whether or not you fix the carburetor, it is a good idea to turn off the gas flow whenever the car is parked for any length of time.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Sunday, March 22, 2015 - 05:06 pm:

Looks like a NH carb. If you have gas coming out where your arrow shows, then you would have to fill the whole carb up and both the hot air pipe (maybe is rusted or stuck in place) and intake would need to be filling to the same level as the top of the spray needle adjusting housing then also your fuel bowl vent would be plugged.
http://www.mtfca.com/discus/messages/331880/377461.html?1386809953


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Sunday, March 22, 2015 - 05:48 pm:

As both throttle & choke levers are cast and an off-set bowl drain, although the bolt in it is not original, you appear to have an early Holley NH straight bore carburetor - quite sought after, by the way.

Gas leak most likely "crud" in the inlet needle seat or a sunken float.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Sunday, March 22, 2015 - 06:26 pm:

Steve - In support of what you are saying to Henry that,...."you appear to have an early Holley NH straight bore carburetor".

Henry's profile lists his Model T to being a 1921,.....isn't that also just about the time period that the factory was equipping new Model T's with Holley NH "straight-through" carburetors?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Vancouver, WA on Sunday, March 22, 2015 - 06:51 pm:

The above advice is exactly right. Most of these carbs need some attention to get into correct running condition. Nice Ford script on the intake also. Looks like this car has set for a while? How long since it last ran and has it been inside or outside? Always nice to get a T running again after a long sleep. Your gonna love it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Sunday, March 22, 2015 - 09:57 pm:

I believe the straight bore was around late '19 into '20 then Holley put the dip into the air passage soon after.


Top of pagePrevious messageNext messageBottom of page Link to this message  By henry h on Thursday, March 26, 2015 - 10:54 am:

Thanks for the advice. After removing and opening it up, it looks like the inside of a tar factory. So it's apart and in for a soak.

But a question about the drain. Clearly this is a side drain, but the drain was moved to the center and a new bowl retention nut from a center drain was used. but the piece in the side drain hole that holds that bolt is tapped correctly for the bolt. And the drain stud does not match that side piece - its the same size but a different pitch. And that holding piece in the side just turns without coming out. the bowl interior is so caked that it's not clear what holds it in. I have links to the parts diagrams and to langs, but what is that side drain bushing?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Thursday, March 26, 2015 - 11:33 am:

That piece shouldn't turn as it isn't suppose to come out ! If it turns now, it will leak gas so you need to simply replace the bowl with the later NH and use the center drain.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Thursday, March 26, 2015 - 11:52 am:

If it's actually coming out of the adjusting needle nut it could mean his vent is plugged. Agree the internal float needle/seat isn't working/not seating but if it's leaking out that high it's overflowing the vent hole too.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, March 26, 2015 - 12:06 pm:

Post a photo showing the base of the carb where the center drain is screwed into. Some of the NH's were made to use a center drain some were not.


Top of pagePrevious messageNext messageBottom of page Link to this message  By henry h on Thursday, March 26, 2015 - 12:25 pm:



If the joint shown by the arrow is not supposed to turn, what holds it in place - is it brazed? Or is it press fit? Again, the bowl is so gummed it's hard to see.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, March 26, 2015 - 01:07 pm:

Your first step should be to remove all the paint/dirt/rust so you can see what you're dealing with.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bud Holzschuh - Panama City, FL on Thursday, March 26, 2015 - 04:49 pm:

Henry

Most of us have installed a petcock at the carb. That way you can easily turn off the gas entering the carb when your not using the car OR in emergency situations like a leaking float needle.

Cheap and good insurance. ;o)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White - Sheridan, MI on Thursday, March 26, 2015 - 07:39 pm:

Henry, How did that new cutout on the starter work out? ;>) Just kidden.
Gary


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Friday, March 27, 2015 - 05:39 pm:

Good point Mark - I have early straight bores and early sway backs that use the offset drain and the later NH has the small, opposite side cutouts to drain the bowl. I can't see why one couldn't take your handy Dremel w/cutoff wheel and strategically install the same type passage as the later on the early type and use a center drain ?

early
late


Top of pagePrevious messageNext messageBottom of page Link to this message  By henry h on Monday, March 30, 2015 - 07:50 pm:

On a straight through holley nh, side drain - what holds the drain body to the bowl? I see that it has the internal thread for the needle valve, but what holds the body itself in? On mine, the body turns, but does not come out. What gives?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Monday, March 30, 2015 - 08:31 pm:

Solder.
Chances are you have a sway back common NH. The location of the drain don't tell you anything esp as you have two drains. AS I stated a photo of carb (without the bowl on) the drain end and a clear side view will help clear things up.
The sway back, if the both butterflys are held open you will see a half moon looking through the carb, the straight through, more or less a full moon.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Monday, March 30, 2015 - 08:35 pm:

Sway back NH models didn't utilize the cast throttle & choke levers.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Monday, March 30, 2015 - 08:50 pm:

That's good to know but as it's got the wrong bowl or drains/plugs it would still be prudent to at least see a good side view.


Top of pagePrevious messageNext messageBottom of page Link to this message  By henry h on Tuesday, March 31, 2015 - 07:42 am:

I am trying to understand how that side drain is supposed to be attached. Here are some better photos. I turns, but does not appear to be threaded on the outside. And do the center and side drain needles have the same tap?






Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, March 31, 2015 - 10:19 am:

That drain boss is part of the bowl and isn't removeable. Likely swaged and soldered in place.

The center drain is only on later NH carbs and the threads are different. You have a nice early straight thru NH, worthy of restoring.








Straight thru with drain on side.


Later Holley NH mostly seen, center drain only, a design change.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Tuesday, March 31, 2015 - 10:19 am:

I'll look at my early bowls but I imagine it was swedged then soldered in place. I do believe the body threads are the same for either the bowl retaining nut and the center drain Can you post a photo looking down the bore ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, March 31, 2015 - 10:27 am:

After the drain was swedged in place it was soldered on the inside.
To correctly be able to drain this model of carb, you will need to bead blast the inside of the bowl getting the area around the drain as clean as you can, then re solder the drain in place from the inside of the bowl. If the seat in it is still good as well as on the needle you can re use the drain plug needle from the center drain. When you order gaskets get one of these to hold the bowl on;

https://www.modeltford.com/item/6211.aspx

Your carb didn't use the center drain. See Steve's photos to see the differences between the center and side drain types.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, March 31, 2015 - 10:32 am:

Two style in comparison, the later on the left.




Later Holley NH for the Ford, the change was for economy, saved the soldering of a boss on the bowl, making the bowl less cost, and one center nut to hold the bowl is also the drain for the drain plug.

That is how Ford got the prices low and kept lowering them on his car :-)


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