Need help with lean stumble on Holley DP

Walker434 said

The IFRs are up top on mine. It's a newer 4779-9 model. I think I bought it new around January 2014. Not sure how to go about moving the IFRs to the bottom as you speak of. I'm still learning the carb tuning stuff so not sure what you mean on that. I think I need to buy that Holley tuning book I've heard people talk about.

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I have an application that likes the IFR up where yours are, but it's pretty rare to find one that doesn't like them lower. I suspect mine likes them up higher because my cam is 255 @ .050 on 340 inches.

It's pretty simple to move them. It requires that you remove the plug from the top where it is and thread the hole at the bottom of the metering block to 6/32 IIRC. Then you get some brass 6/32 set screws (I get them from McMaster-Carr) and you get some number drills and you can start by matching the IFR size you already have. Then tune from there. If it's a bit rich at idle you can go down .003-.004 on the IFR and that's as simple as drilling the set screws and screwing them in.

If want to go whole hog, you can remove the press in air bleeds and IIRC tap the holes to 10/32 and make it so you can change the main air and idle air bleeds.