What did this carb come from?

[SeanPaintsFlames]

It's on my 65 GMC. I'm told the engine is a 250, and has been swapped in from the factory 230. I can't seem to find a replacement carb that has the vacuum line into the base plate like this one, unless the pics on the Auto Zone website of the 65 GMC carb are inaccurate.
Should I just get a newer style carb with the auto choke (or a faster one), and where would this line go instead if I did?
Thanks!!

[aerotruk63]

If it was an American built truck it should have a GMC V6 in it. Canadian built GMC trucks came with the inlines. You should be looking under Chevrolet to spot that carburetor. http://www.autoline.ca/service_locations.htm This is the company we deal with. Most of these carbs share the same rebuild kit. If the aluminum tag has come off the top of the carb, you might see a casting # on the base.

[GruntMoanCough]

Nice lookin' setup you got there.
I'm quite sure that the replacement carb from AutoZone has the provision for the advance.
But, if you want an opinion.............. get a four barrel carb and intake.

[astrochimp]

I have had good luck typing the number off the carb into google.
Just number nothing else.

BUT, I have just searched for a few rochesters.


David

[65ona90]

It looks real close to an old carter single barrel i rebuilt a few months ago. That specific carb was off of a '51 Willy's flathead inline 6. The carb base plates look real close. I believe there should be a stamped metal tag off of one of the bolts if it is a Carter, those numbers would be the model number. If it has one run in a search and see what you can find. Good Luck!

[Eagar1]

A progressive 2 barrel would be an excellent upgrade, and would not sacrifice too much mpg if you keep your foot out of it. you can get an adapter plate to mount on top of your existing intake, and it may even come with a vacuum port in it, or you can drill and tap one. You can actually take vacuum from anywhere off of the intake, even if you need to drill and tap a hole to do it. The diffence with getting vacuum off of a carb is whether it is ported vacuum that is metered depending on throttle position.
I have found that it is best on the older engines to get most of your advance from mechanical, and use the Vacuum to aid in Idle and off Idle response.

[MXmaniac]

That is a Rochester Model B, they began using that carb in the '50s I believe, through around '67 or '68. It was stock on the six cylinders, the one for the 292 was slightly larger though(but same family).

You can't rebuild the one you have? I bought a carb at AutoZone and it was nothing but trouble. It was a later Rochester on my 292, but anytime I slowed down the RPMs would slow way down, sometimes stalling. Even going downhill at a steep grade would do it. No matter how I adjusted the float or anything else, nothing helped a bit. I threw that POS away and found an old Model B, rebuilt it and drilled out the jet and its ran great ever since.

For a replacement I'd use a progressive 2 bbl like Eagar1 said. Tom Langdon's Stovebolt sells them, along with the adapter for the stock manifold, and throttle linkage, and I'm sure he can tell you exactly how to set it up. http://www.stoveboltengineco.com/acartpro/

[SeanPaintsFlames]

Thanks for the replies guys. I did rebuild this one already. It runs alright, but it's actually squirting -not just leaking- gas out the side of the baseplate where the butterfly rod goes through. This makes the truck run a bit rough at idle and it has an off-idle hesitation (I guess) because it's sucking in air through that leak.
Those prog 2 barrels are cheaper than the one barrels! I have an old 2 barrel from a 67 pontiac I had- maybe that could be made to fit? Is there any benefit to actually porting the intake out to accept the 2 barrel instead of using an adapter? Mine has the 4 stud bosses stamped in it already.