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quick question,
1972 - 350 auto - correct cali 7042902.
are the 2 drilled holes in the secondary plate normal or has someone drilled the plate for some reason?
they measure about 3/16".
more importantly, would they/are they cause any problems?
would they add to a bog situation, like when the side spring adjustment is not set properly and plate opening early?
should i block them off? if so best solution?
haven't noticed them on other carbs or in pictures.
Last edited by riverracer au; May 6, 2017 at 01:58 AM.
Reason: added highlight around holes
From: At my Bar drinking and wrenching in Lafayette Colorado
Those are not correct, and should not be there. Not likely that they would actually cause a problem, but I would replace the plates. Somebody probably thought they were duplicating the Pontiac airvalve plates, which have large rectangular notches in them, but failed to pull it off correctly.
The Pontiac airvalves:
The "notches" line up with the pull-over enrichment holes. It causes more fuel to be drawn in by virtue of the pull-over enrichment circuits almost instantly going active. But your holes don't align properly, so they serve no purpose.
From: At my Bar drinking and wrenching in Lafayette Colorado
Agree with the above statements - don't put screws in the holes.
But you have other problems with that carb:
The photo you posted clearly shows that the carb is one of the dreaded commercially rebuilt carbs. It is going to have a multitude of significant problems that will all contribute to your drivebility issues. E-mail me for my "Commercially Rebuilt Carb Problems" paper to see a listing of all the common problems with those carbs.
You have an odd wear mark on the top of your secondary rod hanger - it looks like something has been riding against the hanger making a wear mark on it. If you have something hitting the hanger at that spot, it will prevent the rods from being retracted out of the metering orifices, and it will cause the bog you are describing.
i don't actually have bog, but was wondering the holes would cause one like when the side spring adjustment is not set properly and plate opening early?
in the end didn't put anything in the holes, been like that for the 6+ years i've owned the car, what's a few months more....
as i said, i only noticed as i was doing a once over before a club run the next day.
(was very late here when i wrote the 1st post, may of had a couple of beverages and a brain fade about the bolts )
yes, that grind mark on the hanger is strange, i run the stock twin snorkel air filter setup, so nothing in that area can hit it....
what other signs point to "the dreaded commercially rebuilt carb" look?
the vette was in great un molested condition when i got it, it even still had the smog pump hooked up.
the only time i know of it being touched in the 6yrs is when the engine was rebuilt and my dyno mate change the jet size.
Last edited by riverracer au; May 8, 2017 at 08:08 AM.
Reason: spelling
Those holes are a bit large, but it is a somewhat common practice for some to drill smaller holes in the plates to help with idle/off idle issues with some engines.
If your engine is running fine with them now, I would leave it alone. If you are looking at rebuilding it, they are definitely not stock and could probably be replaced.
"what other signs point to "the dreaded commercially rebuilt carb" look?"
There is a small flat piece of metal pressed down into the vent hole just in front of the air cleaner lid hold down stud. This is done by commercial re-builders to prevent installers from inserting the stud in the vent hole by mistake and damaging the float. They were not produced like this but was/is done to prevent Bubba from blaming the re-builder for damage.
If the carb is working OK and getting decent mileage, just enjoy the ride. If/when you have significant problems, send the carb to Lars for correcting and rebuilding.
1972 quadrajet
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