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Discussion Starter #1
What's an inexpensive metering block that you can easily adjust mains from outside or any way besides taking fuel bowl off?
 

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Percy’s sells a metering block for this it’s not too costly but requires some available but not standard Holley parts for where your going to use them so there is some outside cost. There are some other and older versions that pop up on Ebay from time to time.

Bogie
 

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I'll make this comment ,you can usually get the right jet combo in a few sessions , after that , its a totally unnecessary expense ..
 

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I'll make this comment ,you can usually get the right jet combo in a few sessions , after that , its a totally unnecessary expense ..
Yep, i completely agree, ... unless you are competetively racing and need to make easy weather adjustments on the fly frequently through an event, or are using a shop standard carb for dyno testing and want some easy adjustability....it just isn't worth it for something you are going to find best jetting for and then just leave it set at that point.

Testing and bowl off 4-5 times should get you there for a normal street or street/strip type of deal. Grease your bowl gaskets with Chapstick, Crisco, cooking spray, etc and you'll not even need to replace the bowl gaskets during the jet changes.

Holley used to have a electronic variable main jetting add-in metering block called "Mile-a-Dial" and a performance version called Quarter Mile-a-Dial that you could adjust with a dial on the dash, something like 10 jet sizes smaller from whatever existing jet was in the metering block in increments of two IIRC. It fit between existing metering block and main body IIRC, made the whole carb 5/8" longer on each end.
Have not seen a new one since the mid 1980's
 

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Do not buy the fuel bowls with removable thread plugs to change main jet on a Holley carb. Nifty little jet tool can drop the jet inside the bowl as you attempt a jet change. Then the bowl must be removed to retrieve the loose jet. Been there.
 

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Discussion Starter #7
So, flooring it and feeling results is the only way to adjust jets,w/o using a dyno? I never race it.If so, then you adjust pvcr? Can you use a vacuum gauge at any time for this?
 

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Flooring it will bring on the power valve to riches the mixture. Given that power valves open at different levels of vacuum which is stamped on the side of their hex it is good to know which is in there and to have a vacuum gauge so you can build a map of how much throttle you’re using at specific operating condtions.

In general, and if you not racing general is where you driving habits fit, the opening vacuum for the power valve is selected for that point that is one-half of idle vacuum.

I have found the vacuum/boost gauge that comes from Harbor Freight to be “balls on” and it is inexpensive as these things go, the funky LED colors drive me nuts. I have a very expensive well known made in America brand that reads 5 inches different from the temporary HF gauge. Intuitively because of the cam I run I knew the expensive gauge was probably wrong, I check it against a manometer which confirmed the error. I contacted the maker of the expensive gauge 3 or 4 times but apparently their silence is golden.

Bogie
 
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