Lap a Carb Needle and Seat?

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Model T Ford Forum: Forum 2017: Lap a Carb Needle and Seat?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Saturday, April 08, 2017 - 06:59 pm:

I buttoned up the 24 Touring about an hour ago and fired it up...ready for its first run under its own power and the carb was just gushing gas.

I set the gap between the float and base of the carb with a 1/4" drill bit so I think the needle and seat are worn.

I'm wondering if I can use some valve lapping compound to lap in the needle.

Anyone ever done this?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Saturday, April 08, 2017 - 07:27 pm:

Yup.


Top of pagePrevious messageNext messageBottom of page Link to this message  By john kuehn on Saturday, April 08, 2017 - 07:40 pm:

I chucked up the needle in my cordless drill and used some 150 then 200 grit sandpaper to clean up and polish the needle. Just hold the sandpaper in your hand and get after it. It does a great job.
Then put the needle in the carb seat and tap it fairly firm and it should seat it.

If that doesn't do it, it could be the seat gasket is leaking.

Some times the NH needle and seat will drive you crazy.

You can tell if its seating by the method that's found in the Ford service manual page 210, paragraph 888. It does work. If it wont work you have a seating issue.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Saturday, April 08, 2017 - 07:54 pm:

I've always gone with the Viton tipped needle with no problems. Doesn't seem to get much play here.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Saturday, April 08, 2017 - 09:12 pm:

Any tips for getting a thoroughly stuck seat out?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Saturday, April 08, 2017 - 10:26 pm:

Heat the Carb body as close to the seat fitting as possible. Drip a few drops of water onto the seat fitting to contract & "shock" it. Usually works quite well. On main jets also.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison - Rice, Minnesota on Saturday, April 08, 2017 - 11:17 pm:

Darn it Charlie B, where were you 3 hours ago while I was trying to get that seat out? I had the body hot and was trying to loosen the seat, I was thinking about dropping some water on the sat but wasn't sure the effect it would have. In the end I busted the seat out. I saved the threads and the body itself but just wasn't sure about that drop of water. Next time :-( :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Saturday, April 08, 2017 - 11:26 pm:

I'm going to try it tomorrow....I'll report back.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Sunday, April 09, 2017 - 06:06 am:

This advice is not for carbs specifically, but I don't see why it wouldn't apply. Most people think you should use heat to make one part expand and get the other part out while it is expanded. I can certainly see the theory, but in practice, this works a lot better when assembling than disassembling. Think shrinking a bearing on a shaft. When using heat to disassemble stuck parts, what is usually going on, is the heat is breaking down the bonds where metals have corroded together. Lots of times, even after cooling naturally, the parts are practically only finger tight. Not always, but more often than you think. If it's something you are worried about cracking, try heating it with your torch and then just let it cool, and try loosening it when back to room temperature. If it don't work, then try the quenching thing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Sunday, April 09, 2017 - 08:05 am:

Those carbs have a vent hole in the top.

If that vent hole is plugged, it will create an air bubble that will keep the gas level low and let gas continue to flow.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Warren on Sunday, April 09, 2017 - 08:13 am:

Hi, Hal, Wow is that a two ton truck? That looks like quite a load of lumber in your profile. Also good advice. Don, when heated,brass will expand more than cast iron and will come loose in most cases after cooling because it actually crushes it self some.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison - Rice, Minnesota on Sunday, April 09, 2017 - 08:30 am:

Hal, Also great advice! My problem has become a lack of patience.i know the older I get, the slower I move and I claim I'm being patient. In my mind I'm at full speed and running downhill.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Sunday, April 09, 2017 - 08:46 am:

Great advice from all.....thanks.

I'll be pulling the carb after church today. It's currently all that's standing the way of this car driving for the first time in nearly 5 decades.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, April 09, 2017 - 08:54 am:

For gushing gas, James probably has the answer. Valve seats, etc will allow from a weep to a slow leak, but gushing is a blocked vent with almost certainty. In fact when it gushes it will sometimes appear to "burp" or gush with some regularity.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, April 09, 2017 - 09:41 am:

Don, you may already know this, but the vent is hidden under the data plate.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Sunday, April 09, 2017 - 10:56 am:

Didn't know that Steve. You just saved me some time looking for it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Sunday, April 09, 2017 - 12:43 pm:

If you look back through some of the threads on NH's there are quite a few tips on how to deal with the needle and seat leaking.

I don't do a lot of NH's but among the things that have to be done to get them to work and not leak is to make sure the boss that the seat fits in to is clean. Take a 5/16 wooden dowel, put a piece of sticky back 220 sand paper on it, trim it close, chuck it up in your drill motor and clean it so the gasket will seal against it.

If you don't drill the brass plugs and clean the passages there isn't much point in doing anything else. After they are clean, tap them 8-32 and put tiny Allen head set screws in instead of fooling with the brass plugs.

If you are going to re-do the needle, make sure you keep the angle pretty close to the original taper. You need to work the sides until they are straight, then polish gradually down to at least 800 grit emery paper at the highest possible speed of your drill press or drill motor. 1200 is better. Do not buff it with buffing compound. To check, wipe the tip with a Sharpie, drop it in the seat and turn it gently. Check the fit. If it isn't perfectly round it won't hold. If it isn't round and you whack it with a LBBFH to form the seat, it will hold in that position only and leak as soon as it turns to a new position. Also, the new crap seats they are selling are made out of what appears to be 360 brass which is pretty hard to form a seat in. I make mine out of 260 which is much softer and easy to form a seat in. (Sorry, I can't supply them to anybody)

To remove the seat. Buy one of Jack Daron's seat removal tools. If you can't do that, take a cold chisel and grind it until the tip fits the slot in the seat perfectly. Clamp the carb body on your drill press in exact alignment. Put the new seat tool in the chuck, hold down -- lock it if your drill press can do that -- and turn the chisel with a wrench. It should remove the seat. If it doesn't, heat the body of the carb in the area below the inlet on the OUTSIDE of the body with a propane torch. Then let it cool for 30 seconds or so and the seat will come right out using the down pressure from the drill press to keep the blade from pulling out of the slot.

Worse case scenario, drill the old seat out by using a #3 drill bit, retap the threads 1/4 x 32 and clean up the bottom of the hole with a 5/16ths end mill or the sandpaper on a dowel, make a lead gasket** instead of the crap fiber ones they supply with the new needle and seat sets and you will be good to go.

** Somewhere back in time on this forum is a thread about making lead gaskets from wheel weights -- since most of you probably don't have sheet lead in thicknesses down the 1/32 like I do. You can make a lead gasket in 5 minutes that will cure a whole whackload of leaking seat problems in carbs.

There is a lot more that needs to be done to get them to run right but I gotta get out to the shop and get to work. 30+++ carbs await me.

BTW, Bear in mind that those drawings show all the parts, not necessarily the passages and machined areas of the body.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Monday, April 10, 2017 - 10:56 am:

Stan, many, many thanks for sharing your know-Howe !! MUCH appreciated !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Monday, April 10, 2017 - 11:16 am:

http://www.mtfca.com/discus/messages/599638/677528.html?1474490034


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don - Conroe, TX on Monday, April 10, 2017 - 11:55 pm:

Thank you for the excellent information Stan...it is much appreciated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Tuesday, April 11, 2017 - 12:59 am:

Thanks. Here is the post about stealing a lead weight from your neighbor's pickup after dark.

By Stan Howe Helena, Montana on Friday, July 15, 2016 - 05:04 pm:

Well, after that I probably should offer more help. Feet hurt anyway. Trying to break in a new pair of work shoes that are killing my feet. $275 Red Wings.

So. Go out around the back of the shop where you keep the old Plymouth you are going to get running some day. Steal one of the Lead wheel weights off of it. Take it back in the shop and beat the end of it down until it is about .050 thick and half an inch square. Take your hole punch and punch a 1/4 hole in it. Screw it on the end of the seat -- if you fool with it you can get it on there. Go get your wife's good scissors out of her sewing drawer and cut the lead close around the seat. Now you have a lead gasket that will seal. Take the gasket back off. Put the needle in your lathe or drill press and clean it up with the sharpening stone out of your fishing tool box. None of them will hold from the store. I don't care who is selling them, the new ones ALL leak.

Put seat in a 5/16's nut. The 1/4 - 32 threads will clear the 5/15 sae thread. Set it on the bench or the table of your drill press.

Set the needle in the seat and hit the end of it with a lbbfh just hard enough to make the seal but not hard enough to ruin the seat surface that is setting in the 5/16 nut.

Now Put the seat in and tighten it up until just before you strip the threads or break the end off the seat.

Best gasket you will even have. Takes far less time to do all this than to type how to do it unless you have to go steal a lead wheel weight from the neighbor's pickup and have to wait until after dark to do it.

I actually make them a dozen or so at a time by cutting the lead gasket from a 1/16 thick sheet with a 7/16 hole cutter, punching a hole in the center, threading them on a rod and machining them to size in the lathe. It is hard to cut them to size with a hole cutter and then get the center hole in the right place.

It is pretty hard to get the hard fiber gaskets the suppliers send with the new seats to seal unless every surface is just perfect. I throw those in the gasket drawer to use in other places. These lead ones work far better.

Note that this was free information and worth exactly what you paid for it. Your mileage may vary. Handling of raw lead may not be OSHA approved. Risk of failure is high with any Model T repair not done by a certified shop. Proceed at your own risk. Watch for fallen rock. May be impassable when wet. Trail not maintained by Forest Service. Watch for livestock on road. Open Range. Deer Crossing. Elk Crossing. (Montana only) Watch for Mountain Goats on road. Fraudulent voters will be prosecuted. Auction Sale on left - slow. Park in designated area only.

This information was not approved by an woman and therefore may be inaccurate, faulty and subject to interpretation.

I could do more but I gotta go back to the shop. Working all weekend. Got half a dozen done this week, fighting with a couple Holley G's and a Stromberg OC-2 that need to be in the mail tomorrow.

Need a day off. Need to get my swather working. Got hay to put up.

----------------------------------

Off to bed, it's almost 11, I've been in the shop since this morning with nothing to eat but a Mickey D's sausage bacon egg and cheese about 9 this morning. I'm calling it a day. Almost.

I bought a new car a couple weeks ago. Went in today to get insurance on it. It was about $500 a year higher than I expected. The agent told me it was because of my age, I am statistically a higher risk to have an accident than "LESS ELDERLY" drivers. Depressed and tired, broke and hungry. I'll be better in the morning. ELDERLY!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Tuesday, April 11, 2017 - 07:29 am:

This is the point that needs polishing that Stan was talking about above.

Point


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Tuesday, April 11, 2017 - 09:00 am:

You're not elderly, Stan. You're younger than I am, and I'm only 75.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dallas landers on Tuesday, April 11, 2017 - 09:04 am:

Isnt that elderly profiling??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Tuesday, April 11, 2017 - 10:58 am:

A suddenly leaking carb is very dangerous----I neglected to shut mine off after years of leaving it not shut off at the tank----darn good thing a large pan with two inch sides was under my T after about four gallons of gas was in it over night---gas fumes lay next to the floor----one spark would have probably burned my T and modern car as well as home down just because I did not shut it down.

After years of fire repair I should have known better-----very lucky!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Stroud on Wednesday, April 12, 2017 - 04:28 am:

I have had a Viton needle in my old "beater" '25 coupe for a few years now with no problems. Maybe because of no Ethanol? Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Wednesday, April 12, 2017 - 02:33 pm:

Wow James, great pic, and you can see why they need finishing! egads, someone would sell something like that???


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Wednesday, April 12, 2017 - 03:59 pm:

David, they don't look that bad at actual size. Much as anything, likely a case where the maker has no direct experience with the use, and "quick 'n' dirty" off the lathe is the most cost-effective. The great value is in this forum, with Stan's instruction, we know how the end-user will need to complete the finish to make it workable. More and more, restorers have to become quality control for the parts-makers !


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Friday, April 14, 2017 - 02:32 am:

Rich, very true! I have a machinist's tool sharpening magnifier--looks like a fat fountain pen, and really magnifies stuff, but only when it's right against it, great for checking these things. I have no idea who made it/where to find it, it came with all the other stuff when I bought my lathe (a whole Datsun pickup load of stuff, most of it marked Starrett or Brown & Sharpe, etc.--yes I got a DEAL, about 35 years ago!).


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