Jump to content
Dan693

K Twin Conversion to Dual Carbs

Recommended Posts

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?

 

 

Share this post


Link to post
Share on other sites
 

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....

 

Share this post


Link to post
Share on other sites
 
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

  • Like 1
  • Haha 2

Share this post


Link to post
Share on other sites
 
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

Share this post


Link to post
Share on other sites
 

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

Share this post


Link to post
Share on other sites
 

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
  • Like 3
  • Thanks 1

Share this post


Link to post
Share on other sites
 

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 ?

Share this post


Link to post
Share on other sites
 

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
  • Like 1

Share this post


Link to post
Share on other sites
 

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

Edited by bcgold
  • Like 2

Share this post


Link to post
Share on other sites
 

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

Share this post


Link to post
Share on other sites
 

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:

Share this post


Link to post
Share on other sites
 

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.

Share this post


Link to post
Share on other sites
 
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

Share this post


Link to post
Share on other sites
 
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

Share this post


Link to post
Share on other sites
 

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

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×