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SBL74
Samba Member
Joined: November 25, 2013
Posts: 125
Location: Treasure Island, FL
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 Posted: Sat Dec 30, 2017 7:54 pm Post subject: Solex H44 and intake manifold vacuum |
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I have the dual carb Solex H44 set up on my Thing and a Bus with a type 1 engine. Both use the 009 distributer and mechanical advance. I noticed that one car has the intake manifold vacuum outlets plugged, while the other car has them connected together. Is there a preference?
steve |
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Pruneman99
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Joined: February 22, 2012
Posts: 5013
Location: Oceanside
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| Posted: Sat Dec 30, 2017 8:03 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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The one connected together act as a balance tube. Sometimes it helps tune dual singles, some people have more luck tuning without (plugged).
You can experiment to see what gives you the best idle. Dual singles like to idle on 2 cylinders and the balance tube can sometimes smooth it out. |
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SBL74
Samba Member
Joined: November 25, 2013
Posts: 125
Location: Treasure Island, FL
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| Posted: Sat Dec 30, 2017 8:57 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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Can you explain the "2 cylinder" comment? I think I have heard that somewhere before.
Interestingly, the connection between the two intakes is via 2 rubber hoses that connect to some sort of brass double male coupler. Any idea what that is?
steve |
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Pruneman99
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Joined: February 22, 2012
Posts: 5013
Location: Oceanside
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| Posted: Sat Dec 30, 2017 9:30 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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Because the engine fires 1-4-3-2, #2 robs the fuel charge before #1 can "fill up" so to speak and number 4 robs the charge from #3 causing the engine to kinda lope. With dual 2 barrel carbs this is not an issue because each cylinder has a dedicated carb barrel to draw from. The single barrel feeding two cylinders that follow each other in the firing order can cause the second cylinder to get a leaner charge. At idle, that can cause the 2nd cylinder to get such a weak charge, it causes a miss.
Hope that make sense. A balance tube helps crossover charging helping the idle be more even but some people have better luck with no tube. Either way when syncing carbs, the balance tube needs to be clamped shut or plugged.
The two hoses connected together with a double make barb is probably because they had two short hoses and one double male barb  |
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SBL74
Samba Member
Joined: November 25, 2013
Posts: 125
Location: Treasure Island, FL
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| Posted: Sun Dec 31, 2017 10:50 am Post subject: Re: Solex H44 and intake manifold vacuum |
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Well, it turns out that the brass coupling was a "T" with the third end going through the firewall and up under the car to the brake system. Is this some sort of "brake assist" ?
I guess I am stuck with the 2 carbs being connected, huh? |
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Pruneman99
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Joined: February 22, 2012
Posts: 5013
Location: Oceanside
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| Posted: Sun Dec 31, 2017 1:06 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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| Well if you want vacuum assisted brakes, yeah you gotta hook em up somehow, they need manifold vacuum. |
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SBL74
Samba Member
Joined: November 25, 2013
Posts: 125
Location: Treasure Island, FL
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| Posted: Mon Jan 22, 2018 7:27 am Post subject: Re: Solex H44 and intake manifold vacuum |
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For the dual Solex Kadron setup, on a 1600 1973 engine, should the 2 fuel lines coming from the "T" to the carbs be of approximately equal length? I have one carb that has 2 feet of line, and the other is 4 inches! That seems less than optimal.
steve |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Mon Jan 22, 2018 7:57 am Post subject: Re: Solex H44 and intake manifold vacuum |
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fuel lines being 4" different won't affect anything.
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FreeBug
Samba Member
Joined: March 12, 2012
Posts: 4278
Location: deepest, darkest Switzerland
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| Posted: Mon Jan 22, 2018 10:51 am Post subject: Re: Solex H44 and intake manifold vacuum |
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| Pruneman99 wrote: |
Because the engine fires 1-4-3-2, #2 robs the fuel charge before #1 can "fill up" so to speak and number 4 robs the charge from #3 causing the engine to kinda lope. With dual 2 barrel carbs this is not an issue because each cylinder has a dedicated carb barrel to draw from. The single barrel feeding two cylinders that follow each other in the firing order can cause the second cylinder to get a leaner charge. At idle, that can cause the 2nd cylinder to get such a weak charge, it causes a miss.
Hope that make sense. A balance tube helps crossover charging helping the idle be more even but some people have better luck with no tube. Either way when syncing carbs, the balance tube needs to be clamped shut or plugged.
The two hoses connected together with a double make barb is probably because they had two short hoses and one double male barb |
If your CAM is so inclined....stockish cams idle fine. |
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SBL74
Samba Member
Joined: November 25, 2013
Posts: 125
Location: Treasure Island, FL
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| Posted: Mon Jan 22, 2018 9:12 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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John,
They differ by 20 inches. One line is 24 inches long from the T to the carb, the other line is 4 inches long from the T to the carb. It makes me wonder whether there could be a steal syndrome.
steve |
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UK Luke 72
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Location: Little Britain
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Tue Jan 23, 2018 9:43 am Post subject: Re: Solex H44 and intake manifold vacuum |
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That line length difference won't matter on this engine.
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VW_Jimbo 
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Joined: May 22, 2016
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Location: Huntington Beach, CA
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| Posted: Tue Jan 23, 2018 11:49 pm Post subject: Re: Solex H44 and intake manifold vacuum |
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| SBL74 wrote: |
For the dual Solex Kadron setup, on a 1600 1973 engine, should the 2 fuel lines coming from the "T" to the carbs be of approximately equal length? I have one carb that has 2 feet of line, and the other is 4 inches! That seems less than optimal.
steve |
The lenght will not make a big difference unless you have 6 more feet on one as opposed to the other one. The thing to worry about is having the fuel pressure up too high. I use a Holley fuel regulator, I think it was model 12-804. Set it for 2psi. Made a huge difference in how my carb functioned!
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