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Holly Help

Buckskin7T7V

Well-known member
Joined
May 18, 2001
Messages
144
Location
Ca US
Corvette
1977 Buckskin
Me Again. I running a Holly 4165 spread-bore on my 77. After my smog inspection this pass week, the tech indicated to me, that the carb was running too lean. This carb has revers idle jet needles. This means, when you turn the idle needles in, (clockwise) the mixture richens. He had to turn these needles all the way in and it is still too lean. I was hoping if anyone out there knows, how to richen the "MIXTURE" adjustment on this type of carb. On a standard carb you would reduce the air bleed size. I do not what to do what woud seems the logical thing and drill these out and later find out, that an non-destructive method would have been better. I know that float adjustment is very important and as soon as possible, I will be checking that.
 

silver 80

Well-known member
Joined
Jul 9, 2001
Messages
562
Location
madison,wi
Corvette
1980 silver with blk interior 1987 blue / blue
carb

I don't claim to know allot about them but, could you just go with bigger jets?:gap
tom
 

Buckskin7T7V

Well-known member
Joined
May 18, 2001
Messages
144
Location
Ca US
Corvette
1977 Buckskin
I am not sure primary side jetting would effect the idle mixture. The mixture needles controls things until the throttle opens to a certain point. Then the jetting to run the engine takes over. (What you are referring to.)
I appreciate your in-put and if others can help, jump in. I may-be wrong and if changing the jet size would richen the mixture at idle let me know.
 
M

motorman

Guest
drill out the idle feed restrictions in the metering body about .001/.002. go slow on the drill size as a small change in diameter makes a big difference in richness.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
If you turned the idle mixture screws full rich and the carb is still idling too lean, first thing I'd do is take the carb apart and make sure you've got no problem with fuel varnish, combustion sludge or other contamination that has plugged-up or restricted fuel flow through the idle circuit.
 

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