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motor running lean?

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Old May 12, 2014 | 10:44 PM
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motor running lean?

I got a 78 f150 and I decided to go old school with a 68 289 hi po, motor runs great but always seems starved and have to feather it has a autolite 4100 serious 4 barrel on it. So took it apart nothing out of the ordinary but to me the jets seem to small primarys are 55 and secondarys 63 does this sound correct? Has a little bigger cam in then stock and just freshened motor up heads done little heavier springs nothing major though. Anyone have any ideas?
 
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Old May 13, 2014 | 07:45 AM
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What does "seem starved" mean? Have you looked at your plugs? There is no other way to quantitatively identify a rich or lean condition.
 
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Old May 13, 2014 | 08:40 AM
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Runs fine if you keep it.reved up but wont idle plugs are new in it just seems like it's not getting enough fuel both bowls are full the two times I've popped the top of carb off. Idk if this helped ya much but any ideas you got would be great.
 
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Old May 13, 2014 | 08:49 AM
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I don't understand how you can jump to a diagnosis if you literally have nothing to go on. Telling me the plugs are new does not answer the question, but it's a moot point; jet size has very little impact on idle. For all you know, you could have a vacuum leak. Please connect a vacuum gauge and observe its behavior. If the motor won't idle, then your post should simply state that; not a convoluted question about jet size. This will help you be better at troubleshooting in the future.
 
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Old May 13, 2014 | 11:12 AM
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There isnt any vacuum leaks already checked all that, plugs are white in color meaning its lean correct?
 
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Old May 13, 2014 | 12:30 PM
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Please connect a vacuum gauge and describe the behavior of the needle. This is the only way to accurately diagnosis idle issues.
 
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Old May 13, 2014 | 01:55 PM
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Hijack:
What is an inexpensive tachometer (maybe handheld) to get when setting up a carb? Only option that i have seen is a timing light with tach for $100...
 
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Old May 13, 2014 | 07:07 PM
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Originally Posted by Jklnhyd
Hijack:
What is an inexpensive tachometer (maybe handheld) to get when setting up a carb? Only option that i have seen is a timing light with tach for $100...
Is this cheap enough?

http://www.summitracing.com/parts/an...FRBk7AodwQoAGQ
 
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Old May 13, 2014 | 07:20 PM
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I may just get the digital timing light, not a fan of analog
 
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