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Discussion Starter #1
I have a question about the Holley HP upgrade kit?
http://holley.com/134-300C.asp

The thing that puzzles me about this kit is that it says you can upgrade the 650, 700 & 750 and makes no mention of changing the metering blocks.

From the factory, each of these carburetors has a different part number for the metering blocks, so how can they all be upgraded to a 750 without changing the metering blocks? I read the instructions and it makes no mention of changing bleeds based on which carburetor you are upgrading from. What I am missing?
 

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I've only converted 650's and wondered the same thing about the blocks. The metering blocks don't seem to be an issue but plan on playing with air bleed sizes, especially the low speed bleeds. If you convert and add an off idle lean stumble/ bog, determine the air bleed sizes of the old main body. I insert pin drill bits into the air bleeds and then measure them to figure out what the old main body has. That will give you an idea of where to start to establish a good baseline. Most of the 650's I've converted ended up needing low speed bleeds of about 0.028" to 0.032" but I'm at high altitude. I think the HP body comes with 0.036" bleeds on the low speed and 0.076" on the high speed.

Good luck.
 

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Discussion Starter #4
I've only converted 650's and wondered the same thing about the blocks. The metering blocks don't seem to be an issue but plan on playing with air bleed sizes, especially the low speed bleeds. If you convert and add an off idle lean stumble/ bog, determine the air bleed sizes of the old main body. I insert pin drill bits into the air bleeds and then measure them to figure out what the old main body has. That will give you an idea of where to start to establish a good baseline. Most of the 650's I've converted ended up needing low speed bleeds of about 0.028" to 0.032" but I'm at high altitude. I think the HP body comes with 0.036" bleeds on the low speed and 0.076" on the high speed.

Good luck.
Great help. Thanx 2ton
 

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I converted a 650 and have a stumble,covered a lot of it up with a 42 squirter
I thought it was the other way around low speed bleeds are the outer .076
inner .036 are high speed
 

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I converted a 650 and have a stumble,covered a lot of it up with a 42 squirter
I thought it was the other way around low speed bleeds are the outer .076
inner .036 are high speed
Your right, I don't know why I did that.
 

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If the mainwells are around .145 it will be no problem, the difference to look at will be in the idle feed restriction when going to a larger carb. The old restriction should be removed and the metering block threaded for a changeable restriction. If it came in the upper position I would recommend putting it in the lower like the older blocks had.
 

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My IFRs are stock to what came in a 650 if I remember right they are around .034
What I would like to know is how big are the angled idle discharge holes suppost to be mine are like .090 they look huge to me maybe they have been drilled out?
 

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Discussion Starter #9
Might be tempting to just buy an primary metering block with adjustable orifices too.
 
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