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Old 10-06-2019, 06:19 PM   #1
UncleBill
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Question Multiple Carbs

Proud owner of a 1941 2dr sedan. Equipped with an original flathead with offenhauser heads and 3 deuce manifold. Question is, when adjusting multiple carbs do you adjust idle mixture screws on all three carbs or just the center one? Been turning wrenches for years just never encountered multiple carbs before.
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Old 10-06-2019, 07:00 PM   #2
scicala
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Default Re: Multiple Carbs

Welcome to Ford Barn. If your tri power is set up with progressive linkage, you do all of the idle adjusting on the center carb as far as speed and fuel mixture. The front and rear carbs need to have the speed screws backed off all the way so the throttle plates are seated. Then turn in speed screws a hair...., just enough to keep the plates from sticking in the bores, but not enough to pass any more air (or very very little air). Front and rear also need the idle mixture screws lightly seated to prevent fuel flow.
If running direct linkage where all three carbs open up together, then you need to balance all three carbs to the same idle air flow and adjust the mixture screws on all three carbs.




Sal
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Old 10-06-2019, 09:39 PM   #3
UncleBill
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Default Re: Multiple Carbs

Thank you very much. Very useful info.
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Old 10-07-2019, 05:56 PM   #4
Ol' Ron
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Default Re: Multiple Carbs

If this is a completely stock engine. You might consider blocking off the center carb and running it as a Dual set up
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Old 10-07-2019, 06:55 PM   #5
drolston
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Default Re: Multiple Carbs

Or, run progressive linkage adjusted so that the secondaries do not start to open until half throttle on the center/primary. With opening that late the secondaries will probably not reach full open at full pedal. That will run fine, and even with the secondaries not reaching full open, you will have plenty of carburetor CFM for a stock engine.
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Old 10-07-2019, 07:03 PM   #6
Init1
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Default Re: Multiple Carbs

What O'l Ron said. A stock flathead will have trouble swallowing that much gas and run rich.
Really not worth the trouble unless you like changing fouled plugs alot.
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Old 10-07-2019, 08:47 PM   #7
UncleBill
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Default Re: Multiple Carbs

Purchased this vehicle this past summer. Came equipped with aluminum heads, (high compression?), three stromberg carburators, headers. Unknown whether cam is stock. It doesn't have adjustable lifters. The individual I bought it from received it from the estate of the man who put it together. Recently repaired a distributor problem now I am going to tackle the carbs.
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Old 10-08-2019, 06:54 AM   #8
Ol' Ron
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Default Re: Multiple Carbs

A good book to purchase is JWL's "Flathead fact". The first 100 pages discuss the modifications you can make to a "stock" engine. Along with dyno results for all the mods. This will save you time and money, along with a better running engine.
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