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4A032 Carb float or replacement carb

Steelart99

Registered
The 4A032 engines have always had carb issues when used with ethanol gas. Over the years, there have been various replacement floats and float mods done, but from what I've read, no replacements are still available. I have not seen any solutions poised in several years.

So, has anyone come up with an available replacement carb, or a brass replacement float for these engines?
 

miltruck

Registered
All three of the little military engines use the same carburetor; the 1a08. 2a016 and the 4a032. The carbs are no where to be found and the military never had any individual parts made for them. They expected if there was a carb problem the whole unit would be changed out.
Some people on this site have coated the floats with gas tank sealer which I understand does work, but I would be afraid of the weight change. Best thing I have found is to run the engine totally out of gas by shutting the fuel off @ the tank every time you run. Been doing that with our 3 units and no problems yet with the floats.
Saturn used to have carbs, but I believe they are all gone and Saturn just is selling on e-bay now, not their store anymore.
Good luck.
 

Steelart99

Registered
All three of the little military engines use the same carburetor; the 1a08. 2a016 and the 4a032. The carbs are no where to be found and the military never had any individual parts made for them. They expected if there was a carb problem the whole unit would be changed out.
Some people on this site have coated the floats with gas tank sealer which I understand does work, but I would be afraid of the weight change. Best thing I have found is to run the engine totally out of gas by shutting the fuel off @ the tank every time you run. Been doing that with our 3 units and no problems yet with the floats.
Saturn used to have carbs, but I believe they are all gone and Saturn just is selling on e-bay now, not their store anymore.
Good luck.
I'd seen that Saturn did not have carbs anymore, and I'm hesitant to just coat the float for the reason you stated. The more I've read, the more it seems like the best solution might be to simply replace the carb with a different one and work out the linkages. Thanks
 

gnucklehead

Subscriber
Last Subscription Date
07/13/2019
If you do find a carb from military surplus, it will most likely have the same plastic-coated foam float. Best bet is to find an old chainsaw or something with a Tillotson that has a metal float. I've been seeing some black plastic MD floats on fleaBay, may be for alcohol fuels, I dunno :shrug: I'm interested to hear if anyone has used the black ones.
 

Steelart99

Registered
If you do find a carb from military surplus, it will most likely have the same plastic-coated foam float. Best bet is to find an old chainsaw or something with a Tillotson that has a metal float. I've been seeing some black plastic MD floats on fleaBay, may be for alcohol fuels, I dunno :shrug: I'm interested to hear if anyone has used the black ones.
I certainly don't want to get a replacement that has the same issue! I'm looking for a carb that someone has used sucessfully. :D
 

mdlbldrmatt135

Registered
I have coated the float successfully.

I used model airplane Dope. I was made by Midwest products. It's getting harder and harder to find. I also have one coated in Redkote that I didn't get around to testing last year, hopefully this spring.

The weight added wasn't much, and I didn't notice any weird effects. I will note, that there are Brass floats out there in some carbs, my 4a032 on my MEP-016A has one, and I got it straight from Gov't Liquidation.
 

gnucklehead

Subscriber
Last Subscription Date
07/13/2019
I had him check for a metal float and he posted photos.. It's stamped MD-86A, which has a 07804 (I have old parts lists for ME and MD carbs). Good shape for it's age, c.1956
 

Steelart99

Registered
I had him check for a metal float and he posted photos.. It's stamped MD-86A, which has a 07804 (I have old parts lists for ME and MD carbs). Good shape for it's age, c.1956
I saw that someone had asked for float pics; Thanks GH. It's on its way to me and I'll let ya know how it works out when I make the mod.
 

gnucklehead

Subscriber
Last Subscription Date
07/13/2019
I'm pretty sure you'll be a happy camper :D For reference, the full carb is part# 9786E27 / NSN 2910-01-245-9197, last one I bought was NOS and came with a crap float. Some photos of your adventures would be useful for posterity :brows:
 

Steelart99

Registered
I'm pretty sure you'll be a happy camper :D For reference, the full carb is part# 9786E27 / NSN 2910-01-245-9197, last one I bought was NOS and came with a crap float. Some photos of your adventures would be useful for posterity :brows:
Photos are a must. Thanks again for helping with this. :wave:

So, just for reference, does anyone know of a chart/table that shows the bore diameters of various carburetors? Google has NOT been my friend on this.
 

miltruck

Registered
I think you will find that the metal float will require a very slight trimming on the hinge; they are a little too wide and don't fit down into the recess where the pin sets. Just use a small file or a Dremal tool to fit it to the original 4a032 carb.
 

Steelart99

Registered
I think you will find that the metal float will require a very slight trimming on the hinge; they are a little too wide and don't fit down into the recess where the pin sets. Just use a small file or a Dremal tool to fit it to the original 4a032 carb.
Should be an easy fix for me, and I'm looking forward to working out the carb issues and putting on a starter. Thanks for the tip on where to look / modify

I wish there was an easy way to measure HP. I don't have a spare dyno hanging around the shop. :uhoh:
 

miltruck

Registered
I think most people generally agree that these engines are approximately underrated by a factor of 1.5 or so. That is, the 1.5 hp is really 2.5 hp, the twin 3 hp is really 5 hp, and the 6 hp flat 4 is really close to 10 hp. Of course, the four cylinder I think will be carb limited since it is the same carb for all 3 engines.
Just an opinion, have never seen a dyno graph for any of them.
 

Steelart99

Registered
I think most people generally agree that these engines are approximately underrated by a factor of 1.5 or so. That is, the 1.5 hp is really 2.5 hp, the twin 3 hp is really 5 hp, and the 6 hp flat 4 is really close to 10 hp. Of course, the four cylinder I think will be carb limited since it is the same carb for all 3 engines.
Just an opinion, have never seen a dyno graph for any of them.
All my online research of those working on these has shown that the performance on these is significantly improved by boring out the carb from 1/2" to 9/16" or 5/8". From the testing and research done by those trying to use the engine for ultralight aircraft, the optimal carb bore is 3/4" diameter, but the stock carb can't be bored out to that size.

Also, shaving 0.050" off the heads bumps the pressure up 15-20psi increasing the HP some. Remember, the carb is only feeding one cylinder at a time on these engines so it doesn't make too much difference on how many cylinders there are.
 

Steelart99

Registered
So I received the ebay 'donor' carb that gnuckelhead pointed me to. I stripped out the brass float, which was pristine! I tore down the carb on the 4A032-4 engine and its float was an exact match to the donor carb. I did a slight mod on the brass float pivot as noted above and it dropped right in. I love when things work out that way. While I had the carb apart, I also opted to drill out the venturi to 9/16". Well the new drill I had 'chattered' somewhat, so I got to spend about an hour with a dremel cleaning up the marks inside and trying to get a more polished finish. Reassembly was a breeze.

Put the carb back on the engine and it fired right up. I did have to remove the governor linkage on the engine and then adjust the idle and running speed.

Success on these mods! Next I will probably try to shave the heads down a bit and get the cylinder pressures balanced.

Gotta see if I can find a performance shop that might be able to do a dyno test on the engine so I can get a true reading of what the HP and Torque are on the modified version.

Thanks for all the help and pointers.
 

Attachments

Steelart99

Registered
Pics:
Carb on 4A032-4
4A032-4 carb with old float
Donor Carb
Comparison of both floats
Brass float put into 4A032-4 carb
Drilling out the venturi to 9/16" diameter
 
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