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Discussion Starter #1
Just wondering what Holly Carb jet sizes you are using if you are at around the same elevation as I am. I am in Atlanta Ga at 1000 ft elevation and using 66 size jets on my Holly 4 barrel 600cfm. I think it is running a little rich. What jets are you using?
 

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better to rich than too lean..im at 2200ft i run 74's!!..too lean, you blow the motor!
 

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I would start at the factory Holley jet sizes and adjust from there, +/- 1000' won't change much, unless you are chasing a .1 (if that) in a bracket car, temperature has as much effect probably.
Not sure what jets came from Holley with that carb but search the 'net and you will find out. They came pretty darn close with the jets they set them up with it seems.
 

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What makes you think it's running rich?
 

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My roomate was a mechanic when he was younger and noticed it. I also saw some very light white smoke when idleing last night. May have been water vapor it was so light.
What do the plugs look like?
 

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Discussion Starter #9 (Edited)
I can check the plugs tonight. Last time I checked they had mild black soot on the tip, more on one side than the other. It was mild. Not sure if soot is the correct terminology but you probably get the point. I will post some pics tonight.
 

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What engine combo are you running? If it's idling rich you'll see soot out the tail pipes, on the ground and maybe even on the bumper. White smoke is moisture, blue smoke is oil (often confused with white smoke) and black or dark smoke is rich mixture or loaded up.

If you are really worried, jet down the primary a couple sizes at a time and test drive each time, too lean should cause a serging at an even cruise speed. Come up at least 2 sizes from cruise serge.
 

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Discussion Starter #11
What engine combo are you running? If it's idling rich you'll see soot out the tail pipes, on the ground and maybe even on the bumper. White smoke is moisture, blue smoke is oil (often confused with white smoke) and black or dark smoke is rich mixture or loaded up.

If you are really worried, jet down the primary a couple sizes at a time and test drive each time, too lean should cause a serging at an even cruise speed. Come up at least 2 sizes from cruise serge.
L-48 350 with 441 heads, Z28 valve/springs, summit 1102 mild cam and summit headers.

I did notice some splatter on the ground at idle, it looked more like a little condensation/water rather than soot..... sounds like moisture and light white smoke are what I saw, not rich mixture. Thanks for the description of smoke colors and what to look for at the tail pipes.
 

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I would make sure my idle mixture screws are right before I started jetting. The above post stating 1000' shouldn't require re-jetting is pretty correct. Remember, these cars went all over the U.S. and I don't recall them jetting the carbs by region.

alan
 

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I would make sure my idle mixture screws are right before I started jetting. The above post stating 1000' shouldn't require re-jetting is pretty correct.
alan
I have to agree.
 

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Discussion Starter #15
the idle mixture screws are set at around 1 1/2 turns. Does the idle mixture also affect the "driving" mixture?
 

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the idle mixture screws are set at around 1 1/2 turns. Does the idle mixture also affect the "driving" mixture?
No, but a jet change on the primary side will cause you to re-adjust the idle mixture... The idle circuit pulls fuel from the bowl through the main jet.
 
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