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Author Topic: Dual carbs  (Read 31959 times)

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Offline garage gnome

Dual carbs
« on: March 03, 2013, 09:01:41 PM »
I decided to finally do this mod I've been thinking about to my '53, dual carbs. I had two YFs and plenty of time. So here it is. I got two YF repop air horns that I'll tie into the original air cross over tube.

http://www.youtube.com/watch?v=sUMFx9gbDIQ





« Last Edit: March 03, 2013, 09:02:44 PM by garage_gnome »
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline garage gnome

Re: Dual carbs
« Reply #1 on: March 04, 2013, 09:05:45 PM »
Hmmmm I'm surprised no one responded to this here. Anywho, I hooked up the choke and throttle cables. The chokes work perfectly together. I was running it again today and I noticed that when I revved it up, the engine rocks the jeep side to side a bit. I really think the lead came alive with this. I can't wait to put my OD back together and take if for a test run!

Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline Kenny_Kustom

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Re: Dual carbs
« Reply #2 on: March 04, 2013, 10:09:17 PM »
I like it ! Details on how you did it ?

Offline Carls_jeep

Re: Dual carbs
« Reply #3 on: March 04, 2013, 10:42:41 PM »
Nice setup Nate. You might want to think about running the fuel supply line over the top of the fuel filter to keep from having vapor lock issues. It's best to keep fuel lines as far away from the exhaust manifold as possible.

I will be interested if it increases the power output and acceleration or will it bog out if the throttle is opened fully at take off. Keep us updated.

Have you thought about making progressive linkage for the carbs?

Offline garage gnome

Re: Dual carbs
« Reply #4 on: March 05, 2013, 07:21:01 AM »
The thought of a progressive linkage did cross my mind, but I decided to keep it simple. The fuel line is pretty far away actually. Is no different than where the float bowl of the WO would be. The fan also blows a nice breeze by it too and out the rear hood gap. ;)

Kenny, I traced the gaskets to make my flanges and just cut some tubing with 45s on the ends. Putting the equalizer in was the hardest. You have to keep the two block flanges in the same plane as well as the carb flanges. I also used an Fhead exhaust manifold to keep it clean looking.
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline 3aJeeper

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Re: Dual carbs
« Reply #5 on: March 05, 2013, 08:48:01 AM »
Gnome - I haven't posted mainly because I'm not that smart a mechanic (I'm still at the "Put Tab A into Slot B" level) and wasn't even sure why someone would put 2 carbs on the engine??  :P I guess it's more power, but wouldn't that just red line it all that much faster?

Sure looks cool tho!

-John
1951 CJ3a
F-134 Hurricane engine

Offline garage gnome

Re: Dual carbs
« Reply #6 on: March 05, 2013, 10:17:29 AM »
Yes, the reason is more power. But how does it make more power? Well, its not the delivery of more fuel, that would cause the engine to run rich and that would be bad. This is the gist of it. This allows the engine to breath better. It all has to do with these things called venturis, where the fuel and air mix and the amount of air flow. Try only breathing through a straw only while running or exercising. You'll notice it is rather difficult to keep up with the air your body needs. Same principle applies to an engine. By letting more air flow easily, you will have more performance. This is also why people put 4 barrel intakes on V8s and yank off the 2 or 1 barrels. The engine gets all choked up.

This is a very simplified explanation. There are a bunch more factors and such that I know a little about from working with my hit and miss engines. It is all very complex.


One other thing I noticed too is, it starts much better too. It started great before, but it is even better now! Usually when it is cold, I'll have to choke it and leave it half choked with the throttle on a bit until it warms up. However with the two carbs, I choke it all the way and it fires right up as soon as I turn the key and I can turn the chokes off all the way and it will stay running. �:o Then when it is warm, I can turn the key and it will fire up right away. Just the way I like engines to start. �8-)
« Last Edit: March 05, 2013, 10:22:37 AM by garage_gnome »
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline F Bill

Re: Dual carbs
« Reply #7 on: March 05, 2013, 10:33:44 AM »
Do you have two choke knobs to pull or did you somehow link the chokes?

Did I read it right the manifolds are straight tubing with angle cuts on the ends? I'm surprised you didn't get a couple of u bends and make a curved manifold. of course we all know this is just a prototype for the new polished cast aluminum dual carb setup you will be offering the discerning flathead owner soon.  ;)

Nice work Nate. I still think you need to paint the lettering on the head for even more power.
Owner of the world famous?? Pintojeep 3A and one yet to be named stock project 3A.
Based in central TX and upstate NY.

Offline garage gnome

Re: Dual carbs
« Reply #8 on: March 05, 2013, 10:48:06 AM »
If you look closely, there is a piece of wire between the two carbs and at the second one, you can see the choke cable sticking out. At the rear carb, there are two pieces of wire going into the cable clamp for the choke.

Yes, the tubing is cut and 45s and welded to make a 90. I thought about a bend, but it is so tight there that I don't think it would have worked. Haha, I don't think I'll be getting aluminum ones made anytime soon.  ;D That would cost a small fortune I think!

But my engine is Pontiac blue! That is better than Chevy orange!   :P
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline 3aJeeper

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Re: Dual carbs
« Reply #9 on: March 05, 2013, 01:19:26 PM »
GG - thanks for the explanation. Makes perfect sense. Now I are a little undumber.... :D
1951 CJ3a
F-134 Hurricane engine

Offline athawk11

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Re: Dual carbs
« Reply #10 on: March 05, 2013, 03:48:13 PM »
Nice work Nate.  I was thinking the same thing as Carl on the fuel line and manifold heat.

I want to see your air horns.

Tim
2-1949 CJ3As
1-1946 CJ2A

Offline garage gnome

Re: Dual carbs
« Reply #11 on: March 05, 2013, 07:44:12 PM »
I finished the air horn today. I'll take some pictures once the paint has finished drying.
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline garage gnome

Re: Dual carbs
« Reply #12 on: March 05, 2013, 08:54:06 PM »
Here's the air horn. Nothing too technical. Just two Fhead air horns welded together and a piece of old cross-over tube sticking out.

Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline Ryan_M

Re: Dual carbs
« Reply #13 on: March 05, 2013, 09:00:04 PM »
This is one of the coolest projects I've seen here. Can't wait for the test run video.
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Offline garage gnome

Re: Dual carbs
« Reply #14 on: March 05, 2013, 09:03:45 PM »
Me too! I'm hoping I can this weekend. The machine shop said my OD shifter forks should be done sometime this week. Hopefully it will be cold this weekend and my road will be frozen.
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted