.67 spraybar hole .

[Samuel Hagan JR]

No problem. 

 

[WikiWiki1]

Hell running .100 in a .45 so you take it or leave it at that.

Problem is the aluminum stock one will brake if drilled that thin.

Need to put a K&S brass tube in it. Have it protrude about .120 into the boar.

Should be a .470 carb?

Bringing up an old thread

I have measured the hole in my spraybars on my CMB 67's black carbs with red spraybar and it looks like they are .080" . Does anyone know how far I can drill these out before I need to worry about the spray bar breaking off from engine vibration?
The current configuration has about .029" wall thickness on the aluminum spraybar.

Brent

 

[Roxyflash]

Back when I ran mostly nitro I would turn custom spray bars on the lathe usually made a few that were drilled small so I could drill them out at pond as needed if I remember right I had .090 on my 45 and .100 on my 67

 

[user 27523]

What ever happened to exhaust throttles?

 

[WikiWiki1]

I turned one out on the lathe today with a larger diameter spraybar so I could drill it out to .098". The original spraybar is .137" diameter so I made one that measures .152". That's the largest I could go without drilling out the carb body. Hope to test it out soon if the weather gets better.

Brent

 

[Tom Foley]

Good info on this thread .

 

[Terry Keeley]

Bringing up an old thread

I have measured the hole in my spraybars on my CMB 67's black carbs with red spraybar and it looks like they are .080" . Does anyone know how far I can drill these out before I need to worry about the spray bar breaking off from engine vibration?
The current configuration has about .029" wall thickness on the aluminum spraybar.

Brent

Why?

 

[David Ashcroft]

What ever happened to exhaust throttles?

They are still available

 

[user 27523]

I don't see anyone using them, I was just wondering why? They were very popular back in the stone age. I wonder if anyone ever tried on a gasser? I like to wonder I suppose, if I am told it will not work, that is what I am going to try.

 

[WikiWiki1]

Why?

Over here in the northwest we run at sea level in 60 degree weather then the next week we go over the mountains and run at 1500 feet in 95 degree weather. I want to see if I can improve the fuel draw through the spraybar in the hot weather and thin air. All the info says to run leaner in the hot but everyone ends up richening the needle to get them to run and then there is no mid range throttle response and lower top end. From what I have read a larger hole may help the fuel draw in the carb so maybe the larger hole will allow that in the hot thin air. Anyway I have made 3 different size spraybars so I can fiddle around and see how or if it works.

Brent

 

[David Ashcroft]

I don't see anyone using them, I was just wondering why? They were very popular back in the stone age. I wonder if anyone ever tried on a gasser? I like to wonder I suppose, if I am told it will not work, that is what I am going to try.

Today's after market carbies are superior . However
If you want a new ex throttle I can direct you to a quality made to order product available.folks still race with them.
Message me.

 

[David Ashcroft]

Over here in the northwest we run at sea level in 60 degree weather then the next week we go over the mountains and run at 1500 feet in 95 degree weather. I want to see if I can improve the fuel draw through the spraybar in the hot weather and thin air. All the info says to run leaner in the hot but everyone ends up richening the needle to get them to run and then there is no mid range throttle response and lower top end. From what I have read a larger hole may help the fuel draw in the carb so maybe the larger hole will allow that in the hot thin air. Anyway I have made 3 different size spraybars so I can fiddle around and see how or if it works.

Brent

Remember pipe choice,stinger size etc is going to play a big part also when playing with spray bar sizes..

 

[user 27523]

Today's after market carbies are superior . However
If you want a new ex throttle I can direct you to a quality made to order product available.folks still race with them.
Message me.

Much appreciated!
I used to make my own for my 7.5 outboards but I am unable to do anymore. Still have a couple left from the golden years. Keeping a look out for CMB .21, .45s and a 27 looks like a gentleman, Stu Barr is the one I will need to contact?