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Author Topic: B stamped primary rods  (Read 1600 times)

Offline mcx

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B stamped primary rods
« on: February 10, 2020, 05:46:50 AM »
 Hello Cliff....can the later  quadrajets (1705/1708) that have the air lid  converted to a adjustable APT modified , use the B series primary rods to compensate for their longer length? or do those B series need to be trimmed down to proper length no matter what? Thanks, Mike
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Offline Cliff Ruggles

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Re: B stamped primary rods
« Reply #1 on: February 11, 2020, 03:15:47 AM »
I don't exactly understand the question, but "B" Series primary rods are used in the earlier carburetors with the APT system in the baseplate.

We make and sell the shorter rods for the later APT units with both .026" and .036" tips so no need to modify anything to try to use the incorrect longer rods in them......Cliff
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Offline mcx

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Re: B stamped primary rods
« Reply #2 on: February 11, 2020, 04:22:40 AM »
Sorry for my wording,     Is it possible to just trim the extra length off a "B" series rod to make it work in a "M"series application?
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Offline Cliff Ruggles

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Re: B stamped primary rods
« Reply #3 on: February 11, 2020, 11:51:41 AM »
No, the overall length isn't the issue, it's the distance to the tapered section of the rod that would sit in the jets when the power piston was in the down position.

Use the correct parts here, early carbs get the longer rods, later carbs get the shorter ones.  Most SMAB use "M" series and the others use J, K, L, and P for the most part.  There were a few early units that got "M" series rods in them, late 70's CA emissions Olds units come to mind here.......Cliff
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Offline mcx

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Re: B stamped primary rods
« Reply #4 on: February 11, 2020, 12:22:34 PM »
Cliff, Thanks for taking the time to reply...i thought by making the airhorn APT adjustable (1705/1708) you might be  able to precision place the B series rod  taper in the jet?  I'm starting to like the later versions now as that piston tower has a lot more adjustment and precision than the base plate APT style.
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Offline Cliff Ruggles

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Re: B stamped primary rods
« Reply #5 on: February 12, 2020, 03:30:56 AM »
No, the travel or "range" of the power piston is based on the shorter rods.  The longer ones are still too long and don't raise up far enough when the PP is at the top of it's travel....
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Offline mcx

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Re: B stamped primary rods
« Reply #6 on: February 12, 2020, 03:39:54 AM »
Thanks for the clarification. I'll  stick with the correct short versions.
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Offline Cliff Ruggles

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Re: B stamped primary rods
« Reply #7 on: February 12, 2020, 05:31:37 AM »
We sell two metering rods for the later APT units that use the shorter versions.

Our 50C rod tapers from .050" to .036" and the 44 rods taper from .044" to .026".

I also sell "B" series rods in .039", .042", .043" and .044".....Cliff
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Offline mcx

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Re: B stamped primary rods
« Reply #8 on: February 12, 2020, 03:14:48 PM »
...I just placed an order for those custom rods ..and a gasket!  Thank you.
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Offline Cliff Ruggles

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Re: B stamped primary rods
« Reply #9 on: February 14, 2020, 03:06:22 AM »
Got it...tks...
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Offline mcx

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Re: B stamped primary rods
« Reply #10 on: February 16, 2020, 02:17:50 AM »
...got the custom rods yesterday...very nice product , packing and fast shipping...I measured them with my cheap harbor freight caliper, and sure enough, these are gradually tapered the whole length...thank you.
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