I.D. a carburetor

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FrankR
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I.D. a carburetor

Postby FrankR » Sun Nov 19, 2017 8:27 am

I have this OMC carburetor. Without removing the throttle shaft, I don't have a real good way of measuring the venturi, but it seems to be 1/2"
My question: Is it a 5.5hp or a 7.5hp? I am thinking 5.5.

Chris_P
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Re: I.D. a carburetor

Postby Chris_P » Sun Nov 19, 2017 1:16 pm

Do you have any pictures to help? Casting numbers?

FrankR
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Re: I.D. a carburetor

Postby FrankR » Sun Nov 19, 2017 3:26 pm

Heh, I knew somebody would ask for a casting number. I was supposed to be getting ready to go to church when I was out messing with that thing. Anyhoo, I just looked again and found the casting number between the slow speed needle nut and the slot for the pull choke. As near as I can make it out it says 303, then below that, 045D. It isn't very clear and hard to tell. And written upside down.

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Mumbles
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Re: I.D. a carburetor

Postby Mumbles » Wed Jan 17, 2018 9:42 pm

Hey Frank, still trying to figure out what you have?

I was building a 7.5 carb today and thought I'd compare it to a 5.5 and 3 horse carb. All three carb throats measure .900 - .915 at the choke end but that's where the similarities end. At the butterfly valve end, the 7.5 measures .910, the 5.5 .750, and the three horse comes in at .625. In other words, 29/32nds, 3/4 and 5/8 of an inch. I couldn't get in to measure the venturis.

Also, a 5.5 carb will be drilled across the top in two places to pick up the throttle linkage shaft. The 7.5 carb isn't drilled.
Still searching for a rudder and hardware to fit a KOBAN. ☺

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FrankR
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Re: I.D. a carburetor

Postby FrankR » Thu Jan 18, 2018 7:38 am

Thanks mumbles. So with that info I went out and measured. It fits your description of 5.5hp. Then I beat a hasty retreat into the house. It froze here last night. Yeah, I know, you Canadians don't want to hear our grumbling about being cold.

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wbeaton
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Re: I.D. a carburetor

Postby wbeaton » Thu Jan 18, 2018 1:17 pm

FrankR wrote:Thanks mumbles. So with that info I went out and measured. It fits your description of 5.5hp. Then I beat a hasty retreat into the house. It froze here last night. Yeah, I know, you Canadians don't want to hear our grumbling about being cold.


Grumble all you want, Frank. I think its harder for you folks that aren't used to the cold. I once drove down to Texas in July. I thought I would melt into the pavement. I couldn't get out of there fast enough. It was just a normal weekend to them.


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