over my head

I have a Rochester 2GC. Can anybody tell me the neck size of the carburetor off the top of their head. Some people online say that the 2GC is smaller than a standard 2G model, and some say that all of the Rochester 2bbls have the same neck width.

OLDSter Ralph

2GC means it has a choke. 2G does not have a choke. There were two different sized 2G carbs. Earlier (1957-58) are smaller than later 2G's. I don't have one each handy right now to measure. The bases that bolt to the intake manifold are also different sized. The 2G's were generally used in multiple carb setups because you only need one carb with a choke. Others may chime in with more or better info.

over my head

interesting, I don’t have the numbers with me but I know that the carb is date code correct for a 1972 350, so it’s one of the later ones.

joe_padavano

The first question is, what are you calling the "neck width"? If you are talking about the diameter of the air horn where the air cleaner sits, they are all 2 5/8". Despite what you may read pretty much everywhere, there are actually THREE different throttle plate sizes. There's the large one used on big blocks, the small one used on pretty much everything else, and the rarely-seen tiny ones used only in the 1961-63 215 motors. Every source I've ever seen overlooks that last one.

over my head

that solves my issue. I’m talking about where the air cleaner sits. I want to put a 4bbl air cleaner on the car but need an adapter. But I didn’t know what size adapter I needed because some people complain that the 2bbls are different sizes for different generations of production. But 2 5/8th’s is the most common I’ve seen, so I’ll go for that.

thanks!

joe_padavano

https://www.speedwaymotors.com/Mr-Ga...ch,288312.html

over my head

So if I have a standard Olds 4bbl snorkel, this should adapt it to my 2bbl?

joe_padavano

1966-newer 4bbls have a 5 1/8" air horn. 1965-older are 4 7/32".

OLDSter Ralph

Thanks Joe P. I never knew about that "tiny" one.