Author Topic: does anyone manually check primary rods?  (Read 1678 times)

Offline unruhjonny

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does anyone manually check primary rods?
« on: September 12, 2018, 10:09:38 AM »
Does anyone manually check primary rod sizes?

or maybe more accurately I should ask:
Has anyone measured rods, to confirm sizing, and/or noticed that the stamped sizing was wrong?

I ask, because I stumbled on what I believe to be a mis-stamped rod size.

*disclaimer*

About twenty-or-so years ago, I would regularly pop open early "70" quadrajets, to harvest the "guts"... yup, that was me.
In my defense, locally these carbs were never bought - they would sit, and get crushed with the rest of the car when time came... at least at the yard I went to.
And in all my years of parts scrounging at this yard, I only came across two pre-1973 Pontiac Quadrajets (even 1973-1974 Pontiac Quadrajets were rare); a 7029268 and a 7042264...

Ok, back to the nature of my question;
This past year I grabbed while at hte Portland swap meet two "core" 1973 Pontiac carbs, one was an in-house Carter manufactured unit;
This carb had jets and neeldes with not identifiers;
Two nights ago, I went into my small stash of parts, and decided to pop open a container which had two sets of "47" rods, to measure and compare against the un-numbered rods from the Carter Quadrajet.

Long story short, the "47" rods I grabbed actually measured more around 42 - and upon closer inspection were visually thinnner than the other set of 47's;
I then proceeded to measure several other sets of rods to ensure I was measuring at the right spot, and it appeared as though I was correct - all the other sets I measured aligned with the stamped sizing EXCEPT for this one set of "47" rods...

BTW, the un-numberd pair appeared to be 43...

Offline Macadoo

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Re: does anyone manually check primary rods?
« Reply #1 on: September 13, 2018, 02:36:41 PM »
I recently had the same issue.  The carb was an eBay rebuild special (and boy was it special) so I have no clue how used the rods were.  They were stamped 54 but measured 48.  With reading glasses and a magnifying glass I they looked perfectly round to me and considering how a rod sits inside a jet, I wouldn't expect this from a worn rod.  It's a mystery.

Offline unruhjonny

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Re: does anyone manually check primary rods?
« Reply #2 on: September 14, 2018, 10:58:01 AM »
I don't think I've ever come across a "54" rod;
the ones I have seen range from 32(B) through to 53(C)

Offline Frank400

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Re: does anyone manually check primary rods?
« Reply #3 on: September 14, 2018, 05:12:10 PM »
I check all the ones I put in builds and never came across this "problem" but I'm not that surprised.  I measure everything twice, regardless of what's written on it.  That way, when you encounter a problem while tuning, you can pinpoint it more easily.

   Most of the times, I use new stuff because old jets are sometimes egg shaped.

Offline Macadoo

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Re: does anyone manually check primary rods?
« Reply #4 on: September 14, 2018, 07:30:24 PM »
I don't think I've ever come across a "54" rod;
the ones I have seen range from 32(B) through to 53(C)

I'd have to dig them out but I'm pretty sure they were 54.  "M" series maybe.

Offline Cliff Ruggles

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Re: does anyone manually check primary rods?
« Reply #5 on: September 15, 2018, 03:10:07 AM »
In most cases we replace the jets and metering rods here.  Don't pin gauge any used jets unless you want to get your feelings hurt.

Many rods will measure undersize, or have "flats" worn on them where they were sliding in the jets.

When folks call up here for rebuild kits I recommend installing new jets and metering rods in most cases.  I explain why and most folks purchase new parts to take that variable out of the equation......Cliff