Marvel carb rebuild

[emacq32]

All - have 4 old Marvel carbs to rebuild and and with winter coming, these will be a great project to tackle.

OK, the all jets are stuck and no amount of soaking, coaxing, cursing will release them. These have been sitting for a long time. Tried all means of torx wrenches, sharpened screwdrivers, left-hand bits; all to no avail. So, will attempt to drill them out, re-tap the holes and start over.

So, my question is - what are the 2 tape sizes? (There appears to be just 2) I think the larger jet is a 10-32, but the smaller eludes me. Thoughts?

Also, maybe there is a miracle method to gets these out (like carefully saw the carb in half, extract the old jets and epoxy it back together? (Winking smiley face)

All the online videos make it look so easy - just unscrew them and they pop out. Right....

Any guidance would be appreciated. Thanks

 

[HCooke]

I have rebuild a dozen or more MS carbs. I have never removed a jet. Clean them out with old guitar strings or whatever.

 

[Papillon]

I had the same problem, so I tried heat. I got one jet out by placing the carb casting in boiling water, but this worked on only one jet. I them tried a map torch, which worked on all but one jet.

The torch method worked on the jets of 5 carbs. I think they are stuck in with the varnish residue from gasoline. Drilling out is difficult. I tried and ended up with brass still stuck in the threads. I think the other tap size is 8-32.

Good luck.

 

[Ishmeal]

(quoted from post at 17:15:16 11/16/21) I have rebuild a dozen or more MS carbs. I have never removed a jet. Clean them out with old guitar strings or whatever.
<img src=https://hosting.photobucket.com/albums/q7/Rvrwoods/.highres/IMG_1544_zpsrtqmrggw.jpg>
<img src=https://hosting.photobucket.com/albums/q7/Rvrwoods/Tractors-006.jpg>

Great advice, I've only rebuilt one so far and have been lucky enough to have been able to remove and replace everything. Those tractors are amazing!!!

 

[Papillon]

Also, you will need a good set of gunsmith screwdrivers.

"https://www.amazon.com/gp/product/B003F6FKBA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1"

 

[lha]

Generally speaking,jets don't wear out,but get dirty and filled with gunk. On top of that,the new jets may
or may not be the correct size to make the carb run correctly. A properly cleaned carb,when adjusted
correctly would be better than a carb that has clean,but incorrect jets. I have rebuilt many carbs on
cars,trucks,boats and motorcycles,so a fairly simple N carb is pretty easy. There are still several things
to watch for on a potentially 80+ year old carb,including deeply embedded filth.

 

[chuck machinist]

(quoted from post at 18:02:01 11/18/21) Generally speaking,jets don't wear out,but get dirty and filled with gunk. On top of that,the new jets may
or may not be the correct size to make the carb run correctly. A properly cleaned carb,when adjusted
correctly would be better than a carb that has clean,but incorrect jets. I have rebuilt many carbs on
cars,trucks,boats and motorcycles,so a fairly simple N carb is pretty easy. There are still several things
to watch for on a potentially 80+ year old carb,including deeply embedded filth.

Ultrasonic cleaner with a heater and vinegar and water 5050 three separare 1 hour soakings. Smarter not harder.CM

 

[Royse]

Heat is your friend. Boiling in water works most of the time IF you
have a good gunsmithing screwdriver and the heads aren't already
buggered up from previous attempts.
I have also used a small torch tip to heat them, but use extreme
caution if trying that because the cast is thin in areas.
Assuming these are N series carbs, main and Econ jets
(if equipped) are 8-32, idle jet is 10-32.

I agree with Harold that the jets don't normally wear out, but if
your carbs have set and are rusted, how else are you supposed to
clean the gunk out from under the jets other than to remove them?

Farmall example