HM 100 Carburetor Issues

#1
I bought a Heald Super Bronc a few weeks ago. It will start up just fine but won't stay idling unless you choke it when it tries to stall. You can keep it running as long as you bump the throttle. I have tried to purchase a new carburetor but guess what, they told me they quit manufacturing these 10 years ago (NLA). They don't even offer rebuild kits just individual parts. Does anyone know where I could purchase a carburetor? I know people are still using these 10HP engines, what are they doing for carburetors? New or aftermarket? Carburetor Number 7712H20 Engine Number HM100159027B Serial Number 2236D. Any help would be appreciated!! Thanks, Mike.
 

chrisr

Active Member
#2
I have bought a few carb kits and carbs off ebay and try to shy away from the ones made overseas even though they probably work just fine. I just search for HM100 or 10hp or even HM80 8hp Tecumseh and look for the carbs that have the screw jet in the bowl where you can adjust to get the right WOT and has the idle mixture screw for idling.

The 8 hp and 10hp Tecumseh carbs seems to work ok either way when they have the adjustable jet on the bottom of the carb but you have to be careful to get the correct choke and throttle levers on top of the carb, fuel inlet on the side of the carb that matches your carb.

Ideally, if you can take yours apart and clean it really well would the best bet and add a kit if needed. I am including a link to some kits and a link to a new carb that may not be like yours but give you some ideas on trying to match up one like yours.

Tecumseh hm80 carb kit | eBay

Genuine Tecumseh Carburetor 632351 Fits Certain HM70 HM80 Engines | eBay
 
#3
A quick suggestion is disassemble the carb , lay owut the parts and compare them to hm80/hm100rebuild kits on eBay to see what matches. It's a $10-$15 gamble but probably worth it. Also find a good carb cleaner,soak the body and clean ALL of the passages and you should be OK. Worth a try.
 
#4
I had similar problems with mine. I searched for a new carb on ebay and a few other websites. I found a few but decided to tear mine apart and watch a few youtube videos on how to clean a carburetor as most of this is still fairly new to me. I cleaned all of the gunk out of it and reassembled it and still had the same problem. I then stuck it on a milk crate, started it up and adjusted the idle mixture screw and the screw jet in the bowl. The screw jet in the bowl is what made the biggest difference. It was cranked up all the way. I unscrewed it a touch and it ran great for a long time, then I didn't something stupid... but that is a whole other story.
 

MB165

Active Member
#5
don't worry about parts, some local shops will blow you off, online here is the best place. wouldn't hurt to check the throttle shaft, where it enters the carb body, if that area is worn it causes a small vacuum leak, makes it hard to impossible to dial in a idle mixture. if equipped, the long intake manifolds don't help either the fuel tends to pool up after a long idle time, then you rev it up and think its rich, when its really just loaded up.
 
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#6
I ordered the 6312660A carburetor. It comes with a fully adjustable carb for the WOT and idle circuits, also comes with the original style curved down intake manifold. Purchased mine a year ago off of ebay for $90.00 and it is a perfect match to my other stock HM 80's. They are made specifically for the HM80 engine but I am sure it would work fine on your HM100.
 
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