[Jimbo K Clone]

Morning experts, cold again in TX. I have a 289 k-code, Edelbrock intake, Holley 600, headers and MSD ignition. What size Jets are you guys running?

 

[Woodchuck]

Morning experts, cold again in TX. I have a 289 k-code, Edelbrock intake, Holley 600, headers and MSD ignition. What size Jets are you guys running?

The ones that provide the proper main circuit air/fuel ratio for the engine configuration. The answers could vary across the board depending on the intake, carburetor, headers, camshaft, timing curves, fuel formulation, air bleed size, booster type, etc.

 

[65AScoupe]

I would have to say,

A Dyno could be your friend!

 

[Woodchuck]

I would have to say,

A Dyno could be your friend!

So could "plug reading" and/or a wide-band AFR gauge....

 

[ArizonaGT]

I wish I had wideband O2 thirty years ago. It’s almost like cheating 😜

 

[GT289]

68 pri/72 sec was the hot ticket for a 650. I’m thinking 65 or so on a 600 Holley, with a 70 secondary.

 

[ArizonaGT]

A vacuum secondary 1850 will want less primary jet than that. 62-64 or thereabouts

 

[Hemikiller]

Morning experts, cold again in TX. I have a 289 k-code, Edelbrock intake, Holley 600, headers and MSD ignition. What size Jets are you guys running?

Start with whatever jets are stock in your carburetor model.

 

[GT289]

Start with whatever jets are stock in your carburetor model.

I think most 1850's were 65's in the primary side...... haven't looked one up in awhile.

 

[supershifter2]

Thats a question where one size doesnt fit all. A dyno is the best place to tune a carb to your engine. Even I the Holley fine tuner expert uses a dyno. The dyno gets it right cause I can only come close.

 

[Helmantel]

Start with whatever jets are stock in your carburetor model.

At least for sea level that's a very good starting point. Usually it's everything else but the jets that needs to be tuned for the application. Like the idle feed restrictors. Which are fixed.....

 

[ArizonaGT]

Like the idle feed restrictors. Which are fixed....

…and there’s a way around that 😉

 

[Helmantel]

Yes, I know. But it should have been tunable from the beginning, because in my opinion if there's one circuit on a Holley that needs to be tuned for the application it's the IFR.

 

[Woodchuck]

At least for sea level that's a very good starting point. Usually it's everything else but the jets that needs to be tuned for the application. Like the idle feed restrictors. Which are fixed.....

...with a drill bit.

 

[Helmantel]

Hard to drill them smaller though 😉

(and yes, there are ways around that too)

 

[Woodchuck]

Hard to drill them smaller though 😉

(and yes, there are ways around that too)

https://www.summitracing.com/parts/qft-7-7-10qft or there's always solder.....

 

[Hemikiller]

I think most 1850's were 65's in the primary side...... haven't looked one up in awhile.

Spot on.

 

[Maxum96]

Money well spent to tune your Holley carb.

https://www.summitracing.com/parts/hly-36-181