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Carb Rebuild Woes


Garysriv

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Working towards getting the 65 started.  Drained oil overnite, little marvel mystery oil in the cylinders.  New oil/filter, good 27f battery.  Cranked without plugs until oil press light went out.  All good so far.

Ran into a snag on the carb rebuild.  It has the original 3921S AFB.  Soaked the body and the secondary rod is just frozen in the body, they will not open.  Tried heat, everything.  Kind of "stuck" at this point.

If anyone has a decent 3921 base I'm interested.....

 

 

Edited by Garysriv
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Hi Gary,

  Dont know if you realize it or not but there is a secondary lockout feature on the carb when the choke is applied?

  Dont give up yet. Do a search on this forum using various phrases. There is a fellow named Jon who has a carb business (maybe carb king?) who authored an excellent post about how to unstick a carb. Had something to do with heating in an oven, etc, but from my experience it sounded like a very good method.

  Tom Mooney

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Don't apply heat with a torch, it can potentially warp the body. Take two sinks, fill one with scalding water and the other with ice water. Soak in scalding water then drop in ice water. The sudden change in heat reaction will shock the two metals (steel rod in an aluminum body) and one will expand/shrink faster than the other. This is how I saved my 56 Carter 2347S. It took only four or five dunks in the ice water to get it freed up. After every dunk, firmly grasp the rod and try to rotate it back and forth. Eventually it will give. Good luck!

Edited by Beemon (see edit history)
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19 minutes ago, RivNut said:

If you'll look closely, you'll see that, unlike a  Rochester, a Carter AFB has the shaft built into to the body.  The AFB separates only into a body and a top, no separate base.

Yeah, I guess I meant the base in afb lingo.

 

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39 minutes ago, 1965rivgs said:

Hi Gary,

  Dont know if you realize it or not but there is a secondary lockout feature on the carb when the choke is applied?

  Dont give up yet. Do a search on this forum using various phrases. There is a fellow named Jon who has a carb business (maybe carb king?) who authored an excellent post about how to unstick a carb. Had something to do with heating in an oven, etc, but from my experience it sounded like a very good method.

  Tom Mooney

Yes, lockout not engaged, looks like below someone has a heat/cool idea...

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32 minutes ago, Beemon said:

Don't apply heat with a torch, it can potentially warp the body. Take two sinks, fill one with scalding water and the other with ice water. Soak in scalding water then drop in ice water. The sudden change in heat reaction will shock the two metals (steel rod in an aluminum body) and one will expand/shrink faster than the other. This is how I saved my 56 Carter 2347S. It took only four or five dunks in the ice water to get it freed up. After every dunk, firmly grasp the rod and try to rotate it back and forth. Eventually it will give. Good luck!

Sounds good I'll try it!  I'm going to tell the wife it was your idea though....but there was that time she found my corvair turbo housing in the oven, so I have a history......

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2 minutes ago, Garysriv said:

Sounds good I'll try it!  I'm going to tell the wife it was your idea though....but there was that time she found my corvair turbo housing in the oven, so I have a history......

 

Get it done before she gets home! :o

 

image.png.13a1d4bf2fb59be8ef1f5cf52e3eefa7.png

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We went to the local Junk-Mart and purchased an ELECTRIC toaster oven to cook carburetor parts. DO NOT USE A GAS OVEN! Have freed hundreds of throttle shafts in this manner.

 

On the other hand, when life hands you a lemon, think lemonade. You should get better fuel economy with the secondary not functioning! :P;)

 

Jon.

 

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18 minutes ago, 1965rivgs said:

Gary,

  Jon posted in this thread:

 

Send him a PM and ask about his technique. Please consider posting here for others to benefit from, thanks,

 

Tom Mooney

Check the floats with a weight Gage, they may be filling up with gas.   If OK then lower the settings. Another way to free up frozen parts is to let them soak in transmission oil for a few days.

Edited by retiredmechanic74
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4 hours ago, carbking said:

We went to the local Junk-Mart and purchased an ELECTRIC toaster oven to cook carburetor parts.

 

It also works well for cooking bearing races when assembling transmissions. Every shop should have one!

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On 4/2/2018 at 5:20 PM, Garysriv said:

Working towards getting the 65 started.  Drained oil overnite, little marvel mystery oil in the cylinders.  New oil/filter, good 27f battery.  Cranked without plugs until oil press light went out.  All good so far.

Ran into a snag on the carb rebuild.  It has the original 3921S AFB.  Soaked the body and the secondary rod is just frozen in the body, they will not open.  Tried heat, everything.  Kind of "stuck" at this point.

If anyone has a decent 3921 base I'm interested.....

 

 

The last time I checked his website, Carbking, had a 3921 listed for sale.  www.thecarburetorshop.com

 

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3 hours ago, RivNut said:

The last time I checked his website, Carbking, had a 3921 listed for sale.  www.thecarburetorshop.com

 

Yes, I saw he also has parts so he may have a rebuildable body.  Also one on ebay rebuildable for $75 I'm watching.  First I want to try the hot/cold thing several people have posted.  Been working late this week, may give it a shot tomorrow evening.  Thanks!

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Beware of buying a "rebuildable" anything on eBay.  If it were that easy to fix, the owner would have done it already.  In this case, maybe "rebuildable" means you need to sleeve the shafts, fix buggered pieces, etc. rather just drop in a kit.

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If you're not restoring to a numbers correct status on your car, you can look at other AFB carburetor.  Look in the chassis manual and get all the specs*.  Look at where the fuel inlet is located, where the vacuum outlets are, how the kick down works, and other things like that.  It could be that a 66 AFB would work for you. 

 

*Specs might  include jet sizes, metering rod sizes, and other dimensions.

 

My 64 has a 425 in it, but I run (it was available, rebuilt, and affordable) a 64 carb off of a 401.  Different production numbers but the only difference between the two carbs is something like .002" in the secondary jets.  The 401 carb works fine.

 

 

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I pulled out my 65 chassis manual.  There were 34 different specs for the 65 AFB carbs. #3921 for the 401, #3923 for the 425

 

                                       3921                           3923

Low speed jet                 #68                              #65

Idle port                      .200 x .030                     .185x.030

Sec metering jet         120-158                          120-159

metering rod                   16-219                            16-167

 

These four specs are the only ones of the 34 that are different.  

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11 hours ago, RivNut said:

I pulled out my 65 chassis manual.  There were 34 different specs for the 65 AFB carbs. #3921 for the 401, #3923 for the 425

 

                                       3921                           3923

Low speed jet                 #68                              #65

Idle port                      .200 x .030                     .185x.030

Sec metering jet         120-158                          120-159

metering rod                   16-219                            16-167

 

These four specs are the only ones of the 34 that are different.  

Good info, gives me some options!  I remember seeing the 120 jets when I took it apart.  Hoping the hot/cold plan works tonite,,,,

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5 hours ago, Beemon said:

 

The cats don't reprimand me for working at the dinner table. Also for a quick snack.

Must be a thing, because as I was boiling my carb last nite the cat was hanging close by.  Didn't work, so no snacks.

74.jpeg

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