Older model HL Tillotson carburetors

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Terry D Bentley
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Older model HL Tillotson carburetors

Post by Terry D Bentley » Thu Jan 06, 2011 4:00 am

I have been compiling a list and specs on a lot of older and obsolete Tillotsons acquired over the years. From lawn equipment, chainsaws, industrial motors and karts. Many have been adapted to kart use. If you have any older HL carbs, please include the model numbers, if not already listed. Also include if equipped with a check valve and location of H/L needles if not in the normal places. Below are some of the ones I have documented the specs on fuel passages.
HC-12A, HL-15A, 19B, 19D, 22A, 26A, 63B, 63G, 66A, 88A, 92A, 93A, 101A, 117C, 123A, 134A, 173A, 178A, 194A, 195A, 222A, 227A, 237A, 250A, 293A, 293B, 304A, 307A, 322A, 325E, and Cresent CR1.

There are a ton of newer models in the 300+ range that are used on Briggs, recent production kart motors, and the ones EC Birt offers. But they have plenty of information available. Anyway, lets see what you got and if they are currently in use without any issues. I have a lot of full size 100-135cc chainsaws of different makes from the 50'a/60's that all share a common problem. They dont run well on current pump gas. So I have been tearing down carbs and checking all of the fuel passages. It has turned into a small project and thought it would be worth the effort to document everything. Especially what I end up having to drill out to improve metering the fuel so the saws will run like they should.
Last edited by Terry D Bentley on Sun Jan 09, 2011 7:25 am, edited 3 times in total.

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Scott Kneisel
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Re: Older model HL Tillotson carburetors

Post by Scott Kneisel » Thu Jan 06, 2011 7:45 pm

Hi Terry,
I have been using the HL304E carbs offered by EC and APS on all my older engines. Mac 5, 10, 7, 8 and 49. It is a great carb but I ran into a problem with every one. When the engine is idling, the carb pumps out and the engine goes lean and races. I tried a bunch of things and finally found the problem. The fulcrum lever height was way too low from the factory. I raised it to 0.70-0.75" and now they work great. The carb has a vintage appearance and performs better than any that I have tried.

I have a bunch of older HL and HR carbs that I have been recording the throttle bore, venturi, choke bore and jet sizes but not near as many as you have here. Are you willing to share your data? I have always been curious about the different Tilly carbs.

Good topic,
Scott

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Re: Older model HL Tillotson carburetors

Post by Terry D Bentley » Fri Jan 07, 2011 2:14 am

There is no reason to keep the specs on these old carbs out of public domain. Someone might be able to use the info. I dont mind sharing information on any specific models. Most are the smaller venturi with 13/16 and 7/8 throttle bore. Some are factory alcohol models. I have been very suprised how creative some of the fuel passages are. I dont know why a straight forward route wasnt executed. A few of these early carbs have similar passages to the late model stuff. But others look like a newbie engineer was on acid. These old carbs are challanging for me. My goal is to rework some of them to meter this great pump gas we have, so my old saws can still make a woodpile.

The HL 304 is a great carb and easy to tune. Its been around since the early 80's that I know of. It was the OEM carb on rotary Dap motors. I have one with HR stacks on a Hewland Arrow. If EC Birt waved his magic wand over one, should be a delight to tune. I guess like the HL 227, dont change a good thing if it works. It sure had a long production run.

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Re: Older model HL Tillotson carburetors

Post by Terry Sullivan » Fri Jan 07, 2011 1:52 pm

Scott,

Can you explain your .070-.075 setting? Th HL manual says the "Inlet control lever is properly set when flush with floor of diaphram chamber". Are you setting it above the floor?

Terry

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Re: Older model HL Tillotson carburetors

Post by Terry D Bentley » Fri Jan 07, 2011 2:27 pm

I am betting those settings are measured from top of carb body. LIke with using a depth micrometer. I have never needed to raise higher than thickness of the arm itself above flush on gas carbs. That should be very close to his measurements.

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Re: Older model HL Tillotson carburetors

Post by Terry D Bentley » Fri Jan 07, 2011 11:01 pm

Terry Sullivan wrote: HL manual says the "Inlet control lever is properly set when flush with floor of diaphram chamber".
The lever is only properly set when its metering enough fuel to satisfy demands of the engine.

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Re: Older model HL Tillotson carburetors

Post by Scott Kneisel » Sat Jan 08, 2011 11:25 am

Terry,
The measurement I am referring to is from the diaphragm mounting surface down to the fulcrum lever. Flush is OK for the older saw engines but did not work for my kart engines. Especially my modified Mc9 with boost ports. I am guessing the lever is sticking up about 25 to 50 thou above the cavity. That adjustment is basically as Terry B has said, whatever supplies enough fuel. You need to strike a balance between fulcrum height, pop off pressure and the needle adjustments. It is different for each engine. The higher the fulcrum and lower the POP, the richer it will run. If the lever height gets too high or the POP too low, it will flood out and visa versa.

When I first received the 304E carb from EC, the fulcrum was at 0.085 down from the deck. The POP was 10PSI. With these settings the engine would run away at idle unless I choked it when it started to race. It ran on the track OK but I could not get the engine to 4 cycle no matter how far out the main needle was. I left the POP at 10 and kept experimenting with the fulcrum height and zeroed in on 0.070" for the modified engine and 0.075 for the stock Mc8. Now it idles fine and the HS screw is about 2 turns out to get it to 4 stroke at the end of the straight. Plug is a dark brown, just as I like it.

I use a depth micrometer to measure the lever height, it works nicely.

I like the Tillys and am using the HR carbs on my 91's and 101. They are basically the same story but seem less sensitive the the POP and fulcrum height. Maybe just because the dump so much fuel.

Can you make it to Avon?
Scott

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Re: Older model HL Tillotson carburetors

Post by Chris Hamm » Sun Feb 19, 2012 3:19 am

I have these carbs for sale plus two Mac flatbacks, one alky which needs an ear welded on and one gas which is fine. I also have one OEM Tilly HL107A, as supplied on a PP AH61 years ago, run a few times. The Christensen carbs are alky and do require an external fuel pump or today's Tilly pump parts may be added. I have more images, but more cannot be added here due to REAR limitations. All of these carbs are immaculate inside and out and all have check valves. They are, by their nature and rarity, expensive.


SOLD
Last edited by Chris Hamm on Mon Apr 09, 2012 2:54 am, edited 1 time in total.

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Re: Older model HL Tillotson carburetors

Post by Terry Bentley » Tue Mar 27, 2012 2:55 am

I have added a couple more carbs to the list. Below are all of the ones that come to mind. I know there are some others, just have to put my hands on to confirm.
HC-12A, HL-15A(gas and alky), 19B, 19D, 22A, 26A, 35A, 63B, 63G, 65A, 66A, 88A, 92A, 93A, 101A, 117C, 123A, 134A, 173A, 178A, 194A(alky), 195A(alky), 222A, 227A(gas and alky), 237A(alky), 250A(gas and alky), 293A(alky), 293B(alky), 304A, 307A, 322A, 325E, and Cresent CR1(alky). Also have Hartman 293A, 293B, modified .980" venturi alky carbs.

In the very near future I will be able to bore any of the IKF legal stock carbs to Hartman 980 specs. Hartmans carbs had to have epoxy filler and plug used where the fulcrum arm spring pocket was bored thru. My remedy for this is either downsize the venturi to .960" or if possible to offset venturi enough to rectify the problem. After I get some of these built up and tested, will follow up.

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Re: Older model HL Tillotson carburetors

Post by Jeff Yexley » Tue Jul 02, 2019 12:50 pm

Hello. I'm new and must admit I most likely have very little to contribute as I know very little. I seek an answer if any here are feeling gracious. I have two pioneer RA saws. These saws were fitted with the tillotson hl-22a carb. One of these I cracked overtightening. The other I fear is gone completely as I get no response from the shop owner I entrusted to rebuild the thing. My question is if or not a carburetor exists that fits the saw and is available to purchase. I realize how sophomoric my comments and question must be here among experts and do now apologize. Nevertheless I dearly wish my saws to run and have little to lose by my efforts here. Thank you for your time in any case.
Jeff Yexley
Bradley South Dakota

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