Holley main jets mixing

[David Muro]

Hi everybody!
My Camaro is equipped with a 305 engine, Edelbrock Performer 2101 intake manifold and Holley 1850s carbs. I put a narrow AF sensor, to adjust the carburetor a little better. Before I even put the sensor in, I knew it was running on excess fuel. Then I changed the main jets, from 66 to 64, but there was still a rich mixture, I jumped to 62, which gave a bad mix. My questions are:
Can I use a 64 jet and a 62 jet together? Since I don't have a 63 to test.
Another alternative is to turn 62 to 63 ... but which drill bit should I use?

Thank you all in advance!

 

[CorkyE]

Just a couple things to begin with. I don't think you're going to have much luck with a narrow band sensor trying to tune a carburetor, most everyone uses a wide band. That 2101 intake is a spread bore, and you carb is a square bore. Are you using an adapter for that specific purpose? Where is your mixture rich; idle, cruise, wot? Jets will not effect idle mixture. What are you referring to with a "bad mix"? Two jet sizes is not that big of a swing, you might want to leave the 64's in for a while, see what happens. And if 64 is too rich, and 62 is too lean, then you have may need to address the air bleeds. Couple guys here are good with the bleeds, I've gone sissy with efi.

Edit; I'm seeing where some are using this manifold and a square bore carb w/out an adapter and w/out issue. Guess some are luck, others are not.

 

[G72Zed]

To add to CorkyE's really good and informative reply above.

My answer to question 1 is YES, use the 64 jet on the low side (driver side, so left front) and the 62 jet on the high side (passenger front right). Cross jetting on a dual plane is common.

Question #2- Do NOT drill the jet's, they are measures by flow rates, they may have the same drill size, but entry - exit and length's are adjusted, you will ruin the jets.

 

[pomartin]

As CorkyE mentioned you might want to look into low speed air bleeds. If they are drilled then by all means try idle feed restrictors first, as you can manipulate them with a thin wire, no drilling needed, so you can undo if effect is undesirable.

 

[David Muro]

Guys, thank you so much for the help, sorry for the "short delay" to thank you! I left the carb with a richer mixture, it probably had an air leak too, now it's working fine! Tks

 

[Vettenick]

How do your plugs look?

 

[David Muro]

How do your plugs look?

Plugs are ok!

 

[Vettenick]

Sound like your jetting is OK. It could just be a dirty idle air bleed, or even a bad accel pump diaphragm. I'd rebuild, instead of buying that Edelbrock.