Cleaning a Holly NH Carb

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Model T Ford Forum: Forum 2014: Cleaning a Holly NH Carb
Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Batta on Tuesday, June 03, 2014 - 10:12 pm:

I have take the carb off and need to clean it. Does the bowl come apart? What is the best way to clean it? can I used a parts washer?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Tuesday, June 03, 2014 - 10:17 pm:

If you are sure you want to redo the carb yourself,get the carb book,as it shows all the passage ways you will need to clean,and has good diagrams.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Tuesday, June 03, 2014 - 11:04 pm:

Scott,
Like you, all of us at one time knew absolutely nothing about the basics of the internal combustion engine. As for me, I got my start as a kid dismantling lawn mower engines, so when I got my Model T,at the age of 16, I did know the basics, but, from your question, you appear to have had no experience whatsoever, which is okay. You are doing the right thing by coming here for there will always be someone to answer your questions.

If you are attempting to restore a Model T, you need to first, get the basic information books like the Ford Model T Service Manual and the Model T Bulletin Essentials and thoroughly study them before embarking on this project or you can do some major damage. You should also utilize the valuable information on this forum using keywords.

Yes the carburetor comes apart and the bowl can be removed by removing the bottom valve. Turn it counter clockwise to loosen (the basic rule for bolts is "righty tighty, lefty loosy"). I am attaching a page from the Service Bulletins book showing a cross section of the carb. You will not only need to dismantle it and clean it, you will also need to install some new parts, such as new gaskets and needle valve and seat and make some crucial adjustments. Good luck. Jim Patrick



Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, June 04, 2014 - 12:12 am:

Here are some of the basic books Jim mentioned (one is the carburetor book):

http://dauntlessgeezer.com/DG80.html.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Vaughn on Wednesday, June 04, 2014 - 08:31 am:

I like to clean them with glass beads and then be sure to clean and reseal the idle passageways. You will have to drill out the brass plugs at the entrance to the passageways. I use lead shot to reseal the passageway, the shot must be a little bigger than the hole, then I just peen it into the hole. This method has worked great for me for many years.

A picture I borrowed from the forum several years ago of the location of the passageways.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Wednesday, June 04, 2014 - 08:36 am:

Here are the three books that got me through the complete restoration of my 1926 Coupe from 1970 to 1972, before the internet or the MTFCA. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Wednesday, June 04, 2014 - 08:50 am:

Here are a few more cross-sections of the carb that might help.

If you need to remove the butterfly valves the round disc portions slide through the center of a slit in the shaft and are held in place by a staple. Remove the staple and with a pair of pliers, pull the butterfly valve disc out of the shaft. The shaft will then slide out.

If you want to remove the seats, be sure to use the correct size screwdriver that will fill up the slot. Using a screw driver that is too small will result in stripping out the delicate brass slot.

Have fun, take your time and be gentle. These parts are old and in some cases, very delicate.

Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By john kuehn on Wednesday, June 04, 2014 - 08:52 am:

Scott it really does help to use the guide books that's been suggested.

Many years ago when I started working on the 24 Coupe I inherited from my grandfather the T service manual was my first guidebook I used.

Now the MTFCA has all you need to cover the different aspects of restoring a T.

READ and study them. They really do help.

While asking questions about your T is what this forum is all about using the guide books is really what helps and continues to help me working on my T's.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Wednesday, June 04, 2014 - 09:12 am:

A parts washer will be okay, but sometimes the solvent in a parts washer is too mild and may not loosen the deposits. Using a Xylene based aerosol carburetor cleaner with a thin tube for blowing the carb cleaner through the various ports will be better. Be sure and use eye protection, for sometimes the ports are clogged which could cause the cleaner to shoot back at you into your face.

If the carb is clogged with years of hardened residue you may want to soak it in a bowl (glass not plastic) of lacquer thinner or xylene for several days to soften it all up then using a thin nozzle blow out the various ports with pressurized air from a compressor. Be sure and remove any rubber gaskets that might be attacked by the solvents.

If your float is shellac coated cork, do not use carb cleaner on it for it could soften the shellac. If the float consists of two soldered copper halves, it will be okay to expose it to the solvents and carb cleaner, but it will be best to remove the float while cleaning the basic stripped down unit as shown in the pictures, so as to prevent damage to the float. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, June 04, 2014 - 09:20 am:

A trick I learned from Stan Howe for cleaning out passages: a brass-wound guitar string. The brass winding is rough enough to dislodge dirt and soft enough to not damage the carburetor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By lorenzo leon on Wednesday, June 04, 2014 - 08:46 pm:

Scott. the hardest part for me was to put the butterfly valve disc on the shaft.
and lining up the holes for the brass staple


Top of pagePrevious messageNext messageBottom of page Link to this message  By lorenzo leon on Wednesday, June 04, 2014 - 09:00 pm:

Jim ,Does the auxiliary air comes in under the brass label held with brass rivets ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Wednesday, June 04, 2014 - 10:36 pm:

Yes. Any modern gas will dissolve any Shellac on the float. It should not have a cork float in an NH. Drill the passages with a #42 bit or run it through an ultrasonic cleaner and use a guitar string. Make sure you poke a wire through the hole from the passage at the throttle end of the throat into the throat. That is where the idle fuel gets into the air flow. Before you take it apart, make the position of the throttle and choke plates respective to their position on the shafts. They apparently were randomly drilled and it can be frustrating to find the right position. New plates and shafts will have holes that match.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Wednesday, June 04, 2014 - 11:46 pm:

Yes. There is a hole under the brass label (NH carburetor patent plate). To take the patent plate off, carefully grind off the two round rivet heads with a dremel tool grinding disc. you can drill out the holes with a very small drill bit and get new replacement rivets to secure the label back on. If you decide not to take the plate off, the carb cleaner will dissolve the black paint on the plate that makes the raised brass lettering stand out. The parts places also have new labels that look identical to the originals. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Batta on Friday, June 06, 2014 - 11:20 pm:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Batta on Friday, June 06, 2014 - 11:22 pm:

So books are on order. I know what items 1 and 2 are. They were on the Holly when I took it apart. The others 3 thru 7, I have no clue where they go and which they are. Any pointers would help.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Batta on Saturday, June 07, 2014 - 12:03 am:

Question #2 In the two images below, it looks as if "holes" have been filled on purpose. I have seen other images above in which they are not filled. Why would this be?



Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Vaughn on Saturday, June 07, 2014 - 12:29 am:

Scott - read my 1st post again, you will need to drill those brass plugs out and clean out those passageways. Then I use lead shot that is a little larger than the hole to re-plug the hole. It is important that these passageways be clean so that your car will idle correctly. There are a total of three brass plugs that must be removed so that you can access the passageway. This is really just one long passageway that winds it's way through the carburetor body. The brass plugs just seal access points at different angles of the same passageway. You will notice that there are two small holes on the inside where the throttle butterfly closes. With the throttle closed this passageway allows a small amount of air to be drawn past the throttle so that the car can idle with the throttle closed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Batta on Saturday, June 07, 2014 - 07:46 am:

Mike - thank you. NOW that makes sense.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Todd on Saturday, June 07, 2014 - 10:34 am:

Scott, #3 is for the drain plug, not sure on #4,#5, & #6, but one is for needle valve seat, and one for the spray nozzle, don't know what the other one is for. #7 is the packing for the gas line fitting.


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