Will a holley 6425 drown my 258? - JeepForum.com
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post #1 of 4 Old 02-19-2013, 03:07 PM Thread Starter
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Will a holley 6425 drown my 258?

I was thinking about ordering a new intake from clifford performance but it says its made for no less than 350 cfm. Right now I just have the 1bbl and was going to put a cam in new intake and carb. I'm a gm factory trained tech but at the age of 29 working on carbs may as well be working on alien spacecraft. I have a holley 6425 which from what I've seen is a 650 cfm 2 barrel.? Is this too much or is there a chance or a way to make it work?

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post #2 of 4 Old 02-19-2013, 03:48 PM
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Way too much carb by about 2 times the CFM. Get a 2100/2150 motorcraft or even a Weber. Also IMO stay away from the Clifford intake as its for high reving motors.

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post #3 of 4 Old 02-19-2013, 03:54 PM
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A carburetor uses vacuum both as a signal and as power to meter the gas. If you have too big a venturi, the vacuum will be low and fuel metering will be poor. You can still make the big carburetor work by setting it up rich, so that the engine always has enough fuel.

I'd skip the 4V entirely and go with the aluminum Jeep 2V manifold. Either the Motorcraft 2100 2V or the Weber 2V work well with this manifold. The Weber comes in a 32/36 progressive type, that is like half a 4V in function. It also comes in a 38/38 non-progressive model, for higher performance and less economy. A throttle body from a 4.3L Chevy V6 also works well, but you'll need the rest the stuff to support TBI.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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post #4 of 4 Old 02-19-2013, 03:55 PM Thread Starter
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Awesome. Thanks 19jeep85. Any recomendations for intakes. The reason I want to change it is its thicker I'm guessing to run with factory exhaust manifold and possibly for a different year because power steering attachment doesn't work. Overall what I'm going for is a reliable engine with a little bit of a lope at idle any input is appreciated
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