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Carb vs. venturi & exhaust throttle

Old 11-20-2011, 05:45 PM
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neverthought
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Default Carb vs. venturi & exhaust throttle

Hi, Just got a v-hull with an old K&B 6.5 / .40 with a venturi and throttle exaust. Wondering what the pros and cons are versus a carb. I've never had this type of arrangement. I need some educating here, Anyone?
Thanks.
Pete
Old 11-20-2011, 09:56 PM
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Ron Olson
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Default RE: Carb vs. venturi & exhaust throttle

You just don't see exhaust throttle setups around much anymore. Generally they're messier and harder to set up but if you can get it dialed in you'll have better response that a carbed engine. They seem to be popular on the left coast but around the rest of the country carbed motors rule.
Exhaust throttles are still being used on full-sized kneeler OB hydro's mostly above 500 cc's.
Old 11-20-2011, 10:43 PM
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Default RE: Carb vs. venturi & exhaust throttle

Exhaust trottle works fine, the old Prather was excellent for the K&B .21/.45 but sadly no longer made. The K&B butterfly wasn't as good in use but still worked well enough once setup propely. Since you have it, give it a try and you might like it I think Meccoa still has parts if you want to convert to regular carb and header:
https://shop.mecoa.com/shopdisplayproducts.asp?id=187
Old 11-21-2011, 03:49 AM
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neverthought
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Default RE: Carb vs. venturi & exhaust throttle

Thanks for the info, I will try it as is. But your saying I could simply switch it over to a carb arrangement, correct? if so, can I just throw on a PERRY CARBURETOR for K&B 6.5/7.5CC for example? any suggestions on a carb? or should I forget about it and get a new engine? in other words, is it worth messing around with an antique motor?

Thanks,

Pete 

Old 11-21-2011, 11:51 AM
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Default RE: Carb vs. venturi & exhaust throttle

It is worth putting a carb on if you feel more comfortable that way. It is a fairly old engine and will not perform as a newer design anyway. After you try it "as it is" you'll be able to judge by yourself if it is worth spending more money on it, that DeepVee hull might be a good sport boat for fun running (not racing). Boats don't really need full range trottling as they are used mostly WOT and boats of that vintage with power of the time could run the NAMBA/IMPBA circuit without reducing trottle in many case.
Old 11-21-2011, 12:33 PM
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Default RE: Carb vs. venturi & exhaust throttle

Thanks, that’s why I got the 40" Deep V for FUN running. I have 2 tunnels for racing (K&B 3.5 & 7.5) and the lake I practice on is way to choppy and busy soI keep crashing. I wanted something that could handle a bit of chop and still do 40 to 50mph. (hard to get away from speed when you run tunnels!

Ps. tell Gerry I fixed his "Sea Hawk" and ran it with both 24" and 28" sponsons... wicked...

Can I use the carb from my K&B 7.5 OB on this Inboard 6.5?<o></o>

Old 11-23-2011, 09:22 PM
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Default RE: Carb vs. venturi & exhaust throttle

Part of the reason exhaust throttles became popular is it was easier to experiment with venturi sizes. Instead of making a complete working carburetor with different bore sizes, its eaiser to make a simple venturi and needle.
Old 11-24-2011, 04:56 AM
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Default RE: Carb vs. venturi & exhaust throttle

Can I use the carb from my K&B 7.5 OB on this Inboard 6.5?
Old 11-24-2011, 09:28 AM
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Default RE: Carb vs. venturi & exhaust throttle

If it fits, try it. The worst thing that can happen is it won't run. If the bore of the carb is larger than the 6.5 the only thing that can happen is it will want to draw too much air too freely and won't want to draw fuel as well, or stall near wide open because it will loose its vacuum.
Old 11-24-2011, 11:27 AM
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Default RE: Carb vs. venturi & exhaust throttle

The Venturi for the .40
Old 11-25-2011, 06:54 AM
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Default RE: Carb vs. venturi & exhaust throttle

thanks guy's, much appreciated!

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