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Dan693

K Twin Conversion to Dual Carbs

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Dan693

As I continue my descent in to Kohler big twin madness I wondered.......what if I add a K301 carb to each cylinder instead of a single carb for both cylinders?

Maybe a challenge to sync them but maybe not.

Block bored 30 over, twin carbs, high flow air filters, custom headers.......started at 18 H.P........I say 25 H.P. on a dyno.

 

Anyone ever tried it?

 

 

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ebinmaine

In my younger days I messed with bigger engines a bit but I haven't tried to hot rod a little one... Yet.

Higher compression?

Reground cam?

Ported head or engine?

From what I've read on the singles you can get 1.5 times the original HP of most but lifespan is quite short.

Not sure on the twin cylinder engines....

 

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953 nut
9 hours ago, Dan693 said:

Anyone ever tried it?

Dan, at some point someone has to do it, you may as well be the one!   :handgestures-thumbupright:   We will all be watching, eagerly anticipating the outcome.

 

Related image

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bcgold
4 hours ago, ebinmaine said:

In my younger days I messed with bigger engines a bit but I haven't tried to hot rod a little one... Yet.

Higher compression?

Reground cam?

Ported head or engine?

From what I've read on the singles you can get 1.5 times the original HP of most but lifespan is quite short.

Not sure on the twin cylinder engines....

 

Spot on, life span.

 

Used to be a big deal if you could squeak out 1 hp per cubic inch on pump gasoline.

 

He could get more horse power, Teflon buttons on the piston skirt, port and polish the ports and lighten up the valves maybe install some hybrids with beefier valve springs and don't forget the external oil cooler.

 

Maybe go with a dry sump.

 

Did a search for Teflon buttons seems these are no longer used and have become long forgotten technology

 

 

Edited by bcgold

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diesel cowboy

Might be a little easier to find a 2 barrel carb off of a newer v-twin and go that route.  Have a dual carb setup on my Artcic Cat Prowler and it was a royal pain to sync the carbs.  Ended up having to get a vacuum gauge to make it run right. 

 

2 hours ago, bcgold said:

Spot on, life span.

 

Used to be a big deal if you could squeak out 1 hp per cubic inch on pump gasoline.

 

He could get more horse power, Teflon buttons on the piston skirt, port and polish the ports and lighten up the valves maybe install some hybrids with beefier valve springs and don't forget the external oil cooler.

 

Maybe go with a dry sump.

 

Did a search for Teflon buttons seems these are no longer used and have become long forgotten technology

 

 

Could you elaborate a little more on the buttons?  Never heard of them before and all I can picture is something like that old plumbers thread tape wrapped around the bottom of the piston

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bcgold

To reduce friction within the cylinder bore the piston skirt diameter is turned down and drilled to accept buttons made of Teflon.

 

 

skirt.png

Edited by bcgold
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The Tool Crib

Hey Dan I would love to see this  resurrection as  it could be very interesting. I  have not heard of it been done but why not ?

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bcgold

For your dual carburetor set up make the intake a cross ram. The 300 H, with it's non-ram twin 4 barrel carbs, got a 380 horsepower label, but could also be ordered with a 15 inch set of ram tubes, (405 horsepower).

 

With the longer tubes it would be like having an inter-cooler making the fuel charge more denser.

 

My CCKB Onan twin has a high riser intake with the carburetor mounted well away from the heat of the engine and plenty of air circulation, you could wrap your intake tubes with insulation tape to keep the heat at bay.

 

Also a three angle valve grind will give your engine better breathing with a noticeable power boost.

 

 

twin.png

Edited by bcgold
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bcgold

Once had a 66 Corvair with four carbs 140 horse power that was fun to drive for a week or so, those air cooled engines do not like to be pushed hard. I really do not have any fond memory's of the car but was reminded of it when I was thinking about the roller bearing crankshafts that were available as an aftermarket performance option for the 40 horse power air cooled V-dubs.

 

Living in Canada the purchase of 56 Volkswagen was not one of my most brilliant purchases, flat windshield glass no defroster or heater non synchronized transmission and 40 years later I learn that if I had sold that car today we could have a party to celebrate.

 

If you get ambitious with this project consider a custom built roller bearing crankshaft.

 

 

vw.png

 

 

corvair.png

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bcgold

Now here's a carburetor nightmare, five Chrysler T120's, used in the WWII Sherman.

 

After the war a surplus tanks bought up and used for civilian use were repurposed into tank drills or air tracks, the upper carriage and most of the power train removed and replaced with pneumatic motors to move the machine and rock drills. A large compressor was towed behind to move the tank drill often while at work the compressor could be seen placed some distance from the machine with air supplied to it via a huge bull hose

 

I believe the founder of the Madill company on Vancouver Island was the first to convert the surplus Sherman's into a portable spar tree used to recover felled trees in mountainous areas normally inaccessible by other means, this was of course prior to balloon and helicopter transport.

 

http://www.madillequipment.com/heritage.php#heritage-photos

 

Over the years I have cut up several spars on location, as is where is for scrap along with half a dozen air tracks. Having spent most of my life dealing in the scrap metal industry has given me vast knowledge on many things as some acquisitions have to be researched for resale value above scrap value.

 

With today's cad software and 3D printing and we must not forget the Internets only 5 axis cnc mill, there is no reason to limit how many carburetor the op would like to mount onto his Kohler.

 

Here's a list of free cad software, some of which will run in Windows, I myself abandoned the primitive OS in favor of Linux long ago.

https://itsfoss.com/cad-software-linux/

 

Since I know very little about cad, If it were me I would have a muffler shop bend some tubing then weld my flanges onto the ends.

 

cry1.png

cry2.png

cry3.png

cry4.png

Edited by bcgold

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Skipper

I would like to suggest putting the dual carbs on as a two stage system instead, 1 stage runs as normal, and when carb one is fully open, you start to tap into nr. two. = no hassle of having them run precisely as one. A big thing to steal power is if each cylinder does not yield about the same :-)  That's why balancing is so very important for a good result on engines set up with individual carbs, and I frankly dont think those simple little carbs can realistically be set up to perform exactly the same.

 

Just my :twocents-02cents:

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ebinmaine

Sort of like the secondaries of a 4 barrel.....

 

Nice idea.

I once had a straight 6 with a small mechanical secondary 4 bbl carb.

The second set opened just after passing gear so the engine was already cookin right along because of downshifting.

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bcgold
14 minutes ago, Skipper said:

I would like to suggest putting the dual carbs on as a two stage system instead, 1 stage runs as normal, and when carb one is fully open, you start to tap into nr. two. = no hassle of having them run precisely as one. A big thing to steal power is if each cylinder does not yield about the same :-)  That's why balancing is so very important for a good result on engines set up with individual carbs, and I frankly dont think those simple little carbs can realistically be set up to perform exactly the same.

 

Just my :twocents-02cents:

 

I believe kinetic energy stored in the rotating flywheel will smooth things out.

Edited by bcgold

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bcgold
11 minutes ago, ebinmaine said:

Sort of like the secondaries of a 4 barrel.....

 

Nice idea.

I once had a straight 6 with a small mechanical secondary 4 bbl carb.

The second set opened just after passing gear so the engine was already cookin right along because of downshifting.

 

Those Pontiac SOHC straights six's with the four barrel were awesome engines.

 

 

6.png

Edited by bcgold

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Sarge

There are single throat Weber carbs made for multi-cylinder setups, but they come with a price tag, of course. Synchronization is truly the key, without them being balanced perfectly you'll lose power in a hurry and risk damaging a cylinder. Unless you want to spend a lot of time/money making a multiple carb setup and building the manifold - the easiest way is to modify the current intake into accepting a bigger carb. A bit of flow work in the heads and intake runner/exhaust yields some pretty decent bang for the buck results. I've hotrodded a lot of small engines, some with a lifespan less than a couple of minutes before they exploded, with some being pretty spectacular. Honestly, I'd start with a lot cheaper engine than a Kohler, using a Briggs Vanguard V-twin or similar is half the money.

 

Sarge

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bcgold
11 hours ago, Sarge said:

There are single throat Weber carbs made for multi-cylinder setups, but they come with a price tag, of course. Synchronization is truly the key, without them being balanced perfectly you'll lose power in a hurry and risk damaging a cylinder. Unless you want to spend a lot of time/money making a multiple carb setup and building the manifold - the easiest way is to modify the current intake into accepting a bigger carb. A bit of flow work in the heads and intake runner/exhaust yields some pretty decent bang for the buck results. I've hotrodded a lot of small engines, some with a lifespan less than a couple of minutes before they exploded, with some being pretty spectacular. Honestly, I'd start with a lot cheaper engine than a Kohler, using a Briggs Vanguard V-twin or similar is half the money.

 

Sarge

 

Wonder if the op is going with an updraft, side draft or possibly downdraft carburetors, Weber certainly makes some neat side and downdrafts. I believe Tillotson was the fist to manufacture a multi position diaphragm carburetor.

 

https://tillotson.ie/about-us/

 

We are experts in innovative fuel systems and high performance small engine operation.  Founded as The Tillotson Mfg. Co. in 1914 in Toledo, Ohio, we first manufactured float carburetors for the burgeoning automotive industry.

We grew along with the automotive industry, becoming one of the best-known carburetor manufacturers.  In the late 1940’s, we revolutionized the handheld engine industry with the first diaphragm carburetors. The innovative diaphragm allowed the carburetor — and thus the engine — to operate in any position and led to the creation an entirely new market segment in the lawn and garden industry.  Modern  chainsaws, brush cutters, trimmers and leaf blowers still rely on our technology today.

Beginning in the mid-1990’s, we focused our innovations on professional and specialty diaphragm carburetors. We created the first doTIL FVC Logo 4c(color converte)uble barrel carburetor for the stratified charge (airhead) engine, which enables engine manufacturers to meet the stringent EPA standards in the US and Europe.   We also developed and licensed the high-performance split carburetor for those stratified charge engines which are currently used by engine manufacturers such as Stihl and Husqvarna. In 2007, we introduced the HW series carburetors for use in high performance racing and expanded the line to include HX, HM, HC and HB carburetors. These carburetors are among the most highly engineered carburetors in the world.

Tillotson-TCT-JV2MosTPP Logo in Badge v1bt recently, we have introduced another revolutionary fuel system — the TillotsonTCT — a form of mechanical fuel injection which enables engines to achieve up to 40% reductions in emissions while at the same  providing more power, more torque and more stable engine operation, and we’ve brought our brand of high quality carburetors and components to the consumer market. Our Tillotson Power Products line of Tillotson Exchange logo v9(bigger diamond 2014)portable electric generators, vertical shaft engines and chainsaws offers a growing range of portable products that provide reliable power when you need it most.  And through our Tillotson Xchange catalog, we offer consumers the ability to buy Tillotson brand replacement parts for their non-Tillotson carburetors, all at an affordable price.

 

Our innovative technologies and OE quality make us the carburetor of choice for long life, reliability and performance.  We offer worldwide support and flexible manufacturing alternatives through our manufacturing and support facilities in Ireland, the United States, China and Argentina.

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bcgold

Bench testing for CFM flow, will give you data on how many cubic feet of air your engine is capable of passing through unobstructed and this will determine the largest venturi  that your able to use.

 

https://www.youtube.com/watch?v=swGOAAQmmVU&feature=youtu.be

 

 

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