Carb rebuild

[momark]

I'm in the process of rebuilding the carb for my '63 Ford 4000 172 cu. in. engine. It has the Marvel-Schebler carb. Just checking with the masters for any general(or specific) tips or suggestions before I put it back together. It is soaking in solution as we speak. Any help is appreciated.

mark

 

[BobG_in_VA]

I'm in the process of rebuilding the carb for my '63 Ford 4000 172 cu. in. engine. It has the Marvel-Schebler carb. Just checking with the masters for any general(or specific) tips or suggestions before I put it back together. It is soaking in solution as we speak. Any help is appreciated.

mark

Not familiar with the M/S, but once you finish soaking any carb, wash it in hot soapy water, rinse in hot water, then put about 100 psi air thru all openings/passage ways with a compressor nozzel. If you don't, you'll probably leave a passageway blocked with something.....don't ask how i know this....Good luck. BobG in VA

 

[Soundguy]

Guitar string or fine wire helps clean thos passageways.

Check your flaot by imersing it in a glass of hot water.. look for a trickle of bubles.. if you see them.. float has a hole.

Check flaot hinge, and reset.. make sure it swings free and does not hang on the wall of the bowl. If you keep the brass needle and seat.. use a toothpic to polish the seat... shove it down inthere nad spin vigoresly back and forth between your thumb and forfinger.

Make sure you repalce all the packing.. including choke and throttle shadfts.. otherwise you are asking for a vacume leak.

Soundguy

 

[momark]

Several nice tips there guys, thanks. Soundguy, the kit I bought only has the throttle shaft, no choke. How do you replace the packing and what is the packing made of? I don't believe there's anything in the kit like that either.

 

[Soundguy]

Depends on the manufacturer of the kit. Some kits give you small rubber bushings... or what look like lip seals, or bras backed rubber seals. Some gife you brass shaft covers that knock in like welch plugs, and have felt packing under them. All depends on who you buy the fit from. Napa and Tisco kits are all different.

The carb dip will eat the felt and rubber seals.. so look around.. most likely there are a couply little squishy black seals similar to the throttle shaft seals that you can put ont he choke... or there may be felt packings.. as i said.

On the metal drive in welch plug looking things.. I usually rub a microscopic smear of copperkote around them before seating them. I'm not a big fan of gasket goo's on carb gaskets.. however inthe proper place.. it can help.. Like the shaft seals.. where you don't want a vacume leak.. and a seal may not be perfect, as opposed to a nice flat mating surface like the carb 'halves' gasket, or carb to manifold gasket.. where the dry gasket is fine by itself.

Soundguy

 

[momark]

Well, I finally put that carb back together. I utililized most of the tips you guys gave me. Thanks again for all the info.
As i mentioned earlier the kit I had did not contain new packing for the throttle and choke shafts. They seem to be pretty tight, but there is an ever so slight wiggle in the choke shaft. Not sure how critical that would be, but if it is an issue, is there any way to effectively seal the leak from the outside. Maybe rtv sealant or vaseline? Also, what is the best way to check for vacuum leaks; is it hairspray and listen for a change in the sound of the engine? Any more help would be much appreciated.

Thanks,
mark

 

[Soundguy]

I like to use an unlit propane torch and listen for engine enrichment. of course, do this outside and don't get yourself killed.

You can make felt rings for choke packing.. most walmarts and harwware stores sell felt sheets.

That walmart craft / kid foam sheet may do it.. if it if it is fuel resistant.. felt deffinately will.

Soundguy

 

[Soundguy]

Add:

the throttle packing is the most important when looking at vacume leak.. the choke is the least important.. as you may get just a tad less choke if your shaft is loose..

I'm amazed that there were no throttle packings, or rubber grommets or orings.. the throttle packing is important.

I think I'd hit harbor freight and get a cheapy nitrile oring pack and find one that fit over the throttle shaft, and into the recess, and use it sandwhiched between the brasskeeper and the housing.. couldn't hurt. Who made that kit? Yuck! Every tisco or napa kit I've bought had new shaft packings..

Soundguy

 

[momark]

Soundguy,

That kit I had was made by Calco. I got it at a local farm supply store for about $21. I took the carb back down to the farm today to put it back on. On the way I stopped at a Ford tractor dealer to get an O-ring for the power adjust needle(didn't have one of those either) and I asked to see one of their carb kits for my carb. They use an after-market type(didn't catch the brand) and it had many more parts than mine did. Every brass piece was in there; all jets, needles, seats, etc. Is all mine had was the needle and seat, that's it. Theirs did cost about $42 dollars, but if your going to do it you might as well do everything I figure. Incidentally, I didn't see any shaft packings in their kit either, but coudn't be sure about that.
Anyway, I put the carb back on the tractor and tried it out. It started fine and sounded good. I tested it for leaks with the propane and it didn't seem to have any. Maybe I got away with something, not the way it usually works for me! Really didn't get to test it under much of a load yet though, so I'll just have to see when I do that.
For future reference, which kits do you prefer and where do you get them? Thanks again for all your help.

mark

 

[Soundguy]

42$ sounds like a full kit sans the float.

I'd bet that the NH kit had a rubber or felt packing somewhere in the kit.

Soundguy

 

[momark]

Soundguy... well, I finally got to run the tractor a little more and sure enough, under a load it still was falling on it's face. This is after per manual initial settings on carb. I pulled the plugs and they were already getting a little sooty after only a few minutes of running. So, assuming it was running a little rich, I leaned it out a little more and that only made it worse. So, I backed the main adjusting needle out quite a bit(enriched) and it ran much better under a load but the plugs were quite sooty after that. Also could see some vapor from the pipe. Incidentally, when I adjusted the idle air needle I turned it all the way in(enriching) and there was no noticeable change in the engine(something not right there). I'm wondering if there is anything I can do to get the plugs to stop fouling and still have adequate power? btw, it seems to be getting good spark, especially from the coil. In a bit of a quandary. Any help would be much appreciated.

Thanks, mark

p.s. I'm not really sure what the relationship between the main and the idle
air adjustment is. A brief explanation would be helpful.

 

[Soundguy]

The small side pointing needle is the idle adjustment, in to enrich... And it has almost no effect on engine rpm once you are over 400 rpm or so.

Main (downpointing ) needle is out to enrich.

My 8n has to be run pretty rich to not stumble... makes her smoke a tad.. but. who cares... plugs don't like it.. but I change them once a year anyway.

Sometimes a situation in which you have to excesively enrich indicates a fuel restriction, or a vacume leak.

Soundguy

 

[momark]

So, I guess it's maybe a situation of living with the lesser of two evils, eh? Do you think your 8N hss one of those two problems(fuel restrict. or vac leak)? I checked for vacuum leaks on mine with the propane bottle, per your instruction. Didn't seem to have any, but I will try again.
I guess a new carb would be the sure cure? A bit pricey though, I'm sure.

mark

 

[Soundguy]

I'm sure my carb could use a good cleaning, and that's probably the enrichment issue on mine.. fuel obstruction thru carb venturi orifices and jets. When it gets bad enough, I'll rebuid a spare carb i have on the shelf, and then swap them... That's what i did last time it got that way... About every 4 years or so I do that...

Soundguy