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Question for the carb guys.
I have a pre pollution 308 early HQ quadrajet on my 253 HG.
I want to change primary jets from 76 to 70’s to suit the 253’s smaller capacity.
Question is, Do I also have to change the 308 45B metering rods or will they be ok to stay?
Any help appreciated
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j.williams |
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Just copy what is in a WB or VC-VK. Or buy a rebuilt carby off one of them.
From memory on an XT5 engine has the same secondaries for 4.2 and 5.0 but primaries are different. Look in WB parts book. |
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Already has the correct CX secondary’s. A lot of confusing info out there but have sort of established that the blue 253 used 70 jet’s but can’t find any info on the correct primary metering rod’s. Edited by user Monday, 18 November 2019 9:06:07 AM(UTC)
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j.williams |
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Hi HGV8 , 49-P is the metering rod you need. Thanks Mark. |
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I suggest you talk to Mick at MLP Carburettors. You will get the right answer.
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Originally Posted by: justgm  Hi HGV8 , 49-P is the metering rod you need. Thanks Mark. correcto... the 'blue' 2fiddy3s with Quaddies used these don't use the 45s, a .045" rod has a rod diameter of .045" (and a small diameter "power tip" of .026") The larger (.045" or .049") section of the rod is positioned in the metering jet during light throttle operation and needs to be matched to the primary jetting used on whatever engine. A 45 rod is wrong size hth |
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Originally Posted by: HK1837 Just copy what is in a WB or VC-VK. Or buy a rebuilt carby off one of them.
From memory on an XT5 engine has the same secondaries for 4.2 and 5.0 but primaries are different. Look in WB parts book. HK... the secondarys use a different coded rod .. CX (4.2) v DP (5.0) on blue/silver/black XT5 Improved Performance engines but actually, a CX rod is the better of the 2 GMH used. I use them in 308 Quaddies I build as they have a better 'power transition' to WOT (aka less bog) |
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