Help me fix lean on power issue - Holley 4150

wsutard

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beanhead

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I see. Then I just drill a hole in the set screw to match the size opening I want?
Yes, and I always measure the bits at the shank with a caliper to verify they're the size they're supposed to be, and make a chart/list/whatever. It helps for reference or if the drill index spills (it happens LOL!)
 

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wsutard

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@68 HEMI GTS I just checked my new proform metering block and it isn’t tapped already for the lower holes. They look like they will be tricky to tap.

Question, if this is what is needed to properly tune a Holley then why doesn’t Holley make these ports tunable?
 

beanhead

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IFRs on the bottom are usually better, but if they're in the high position just go with them for now. Or did they not give you replaceable IFRs at all? I would think an aftermarket block would?

Here's the factory stock primary block from a Quick Fuel '750 Street-Q'..
20190910_175305.jpg


(You want the 1/8" long screws btw)
 

wsutard

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IFRs on the bottom are usually better, but if they're in the high position just go with them for now. Or did they not give you replaceable IFRs at all? I would think an aftermarket block would?

Here's the factory stock primary block from a Quick Fuel '750 Street-Q'..
View attachment 832562

(You want the 1/8" long screws btw)
Are brass mandatory or can I use stainless set screws? I can’t find any brass local, just stainless. I understand that stainless will be harder to drill out.
 

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Just me, I wouldn't use stainless...you're correct that they're harder to drill, but the bigger issue is they will not get along well with the metering block material. You can get brass from McMaster-Carr. Summit also has quick fuel branded blanks, part# 7-25-10QFT. But- these have a small head on them, so you may have to drill the first part of the hole slightly bigger to accommodate.
 

68 HEMI GTS

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Are brass mandatory or can I use stainless set screws? I can’t find any brass local, just stainless. I understand that stainless will be harder to drill out.

Beanhead is correct. Those little drills will never go through the stainless. Gotta use brass.
 

wsutard

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@68 HEMI GTS @beanhead i finally have my taps done. Now ready to drill out the set screws.

Need to confirm the sizes to start with.

Lower ports on the carb side are .112 stock. Your post earlier said drill to .078.

for the metering block side, stock is .092. Based on how much you recommended lowering the carb side I’m assuming I should go with .064.
 

68 HEMI GTS

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What port are you referring to on the metering block? Start with .078 for the transfer slot restriction. It will take some experimenting to find out what it like. I always start fat and work down.

Since you have numbered drills can you lay out all the bleed sizes in the carb?
 

wsutard

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What port are you referring to on the metering block? Start with .078 for the transfer slot restriction. It will take some experimenting to find out what it like. I always start fat and work down.

Since you have numbered drills can you lay out all the bleed sizes in the carb?
This port you are pointing to on the metering block. I taped that and set it to .61 (51) from stock of .92 (42).
I figured I would just give these a shot so the carb is back on right now.
I jetted back up to 80 so I can have the fuel I need on power. Hopefully these restrictions will raise the cruise a/f.
 

68 HEMI GTS

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IFR should be in the 30’s. Try .034. Remove the high one.

What’s your MAB and IAB sizes?
 
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wsutard

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IFR should be in the 30’s. Try .034. Remove the high one.

What’s your MAB and IAB sizes?
Sorry but these acronyms mean nothing to me ¯\_(ツ)_/¯

when you say “remove the high one” do you mean this one?

84841B51-BF39-4E6D-A5D5-A5F9F0205244.jpeg
 

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