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johnmyron
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-- 10-24-2017 @ 4:24 PM
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I seem to be constantly plagued by rich running, exhaust smelling Flatheads. My 53 sunliner has the usual model 94 Ford carb made by holley I believe. Have kitted it before, and scr*w*d with the float level, etc. Having similar problem with my 48 F1 that has a 49 or 50 car motor. It has a Dennis Carpenter repro new carb.
After reading a bit, wondering if the most likely problem is the kick in vacuum of the power valve, or do I need smaller main jets?
Any of you old experienced dudes (like me) have any suggestions on what to try first?
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Yokomo99
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-- 10-25-2017 @ 4:36 AM
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I have several questions I am assuming a stock engine.
Is the vacuum advance hooked up (Really Important) and are you using the stock fuel pump? If so what is the idle vacuum level? The stock power valve is set for 7.5 mm Hg and as long as your idle vacuum is above that it will be fine.
If your engine has backfired repeatedly it can rupture the power valves diaphragm and cause the power valve to leak. The power valves are also known to have sealing issues with the gaskets in some rebuild kits. Also the fuel pump diaphragm could be leaking into the crankcase and as the engine warms the vapors will come out of the road pipe and give the rich smell. Blocked idle air bleeds will make it rich as well. Check fuel pressure the stock needle and seat are really only good for about 2.5 psi so anything above that can overwhelm the float and overfill the float bowl.
Lots of possibilities. This is the kind of thing that leads mechanics to drink and tear out their hair.  Hope this helps.
Matt
Be sure to check out my YouTube pages at:
https://www.youtube.com/user/MatthewBergin1
https://www.youtube.com/channel/UCJCdOfmXtM8xO9nXeQ-iSQQ
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ken ct.
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-- 10-25-2017 @ 6:01 AM
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There are a # of things you can do to a DC carb. First get rid of the elstomere rubber accelerator pump use a leather one. Second get rid of the 7.5 # power valve (they open too fast for the engineand loads it up on too much gas) use a 5.5 # work much better.Third get rid of the rubber tipped inlet needle and use a all steel one. Then you will have good quality parts in your kit. Retired carburetor builder. Still selling above parts for carbs , fuel pumps and distributors. Ken ct. cell 1-203-260-9780
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johnmyron
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-- 10-25-2017 @ 3:33 PM
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Matt-Thanks-this is quite useful-both are stock engines, and vacuum advance works well-have checked by revving engine with a timing light watching the advance on the crank pulley. The Sunliner uses an electric fuel pump and will check the regulator for pressure. Quite sure it is low tho. The pickup uses the engine driven fuel pump, so inlet pressure to the metering valve should be ok. going to pull both carbs down and check main jet sizes, and kit them with correct power valve, etc.
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johnmyron
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-- 10-25-2017 @ 3:35 PM
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Ken-thanks so much -will use all the info
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ken ct.
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-- 10-25-2017 @ 4:53 PM
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If the engine driven pump is of new manufactor its probably made in China, Poor quality diaphrams and the big diaph. spring is too strong causing excess pressure 2 1/2 -3 # is best pressure. ken ct.
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