Rochester 2G Carb Main Jet HELP!

Hello all,
I am in the process (first time ever) of rebuilding a carb. I have it all torn down. I checked the Main Jets size and they say 56. I found a resource that states my 63 Buick Fireball should have 44's. In looking at the other data it appears 225 had 56 jet ranges, so now i am confused. I know i have a 198 by block numbers, but i am thinking the PO changed the carb out instead of rebuilding it, or actually installed larger jets (maybe it was in higher altitude etc...as i am not sure how or why one would change the sizes or what effect it has). So since i have been having problems with the motor start, bogging on acceleration, etc thus the carb rebuild, should i place 44 back in, or just put the old 56 back in?

Seems as there is a notation on the data sheet that says

Here is the data link..

http://www.carburetor-parts.com/Rochester-2-Jet-Main-Jet-Specifications_ep_525.html

http://www.carburetor-parts.com/Rochester-2-Jet-Main-Jet-Specifications_ep_525.html

Thoughts?

 

Look for numbers stamped into the left side of the Rochester directly below where the gasoline hose enters.
They are not always present many were tagged on the top side and later the I.D. tags were removed.

This is a 2G "C" meaning that its an automatic choke version of the Rochester 2G.
These are exceptional quality for original equipment carburetors.

If the carburetor was set up for high altitude the main jets would be smaller and not larger.
It certainly seems most likely that your carburetor was removed from a 225 V-6.

Yes too large of jets for your displacement will adversely effect the acceleration.

 

You must identify exactly what you have !

If you cannot find a number then you will be forced to estimate the original carburetor application via its internal components.
You cannot simply swap any old carburetor onto some other engine.
An appropriate carburetor should be taken from a donor engine having a displacement within 5% of your engines discplacement.
In other words the correct carburetor is selected and tuned to suit an engines volumetric flow.
An engines volumetric flow is mainly dependent upon its displacement along with many other additional factors.

 

Yes thanks. I did not swap it a PO apparently did. That's why I am thinking i need to go back to 44 jets instead of the 56 I found installed.

 

12 jet sizes is too much of a change to compensate for only a 27 cubic inch difference. I'm thinking that there has to be other variables involved....perhaps a smaller venturi size on the original 198 carb.
I would rebuild what you have and see how it works...if it's still running rich, try dropping the Jets 2 to 4 sizes, no more than that.

 

Yeah I will most likely put the old 56's back in but still wondering if I should try the 44's that were original call outs. I guess a lot has changed with fuels from the 60's. I guess I will also have to place new plugs and keep an eye of the color to determine rich or lean status. Sound like the best plan?

 

Digging up an old thread here, but I also have a 198 with a 2G and my PO had installed size 44 jets as well.

I was having a heck of a time tuning my carb, and wondering if the small jets may have been the issue (although it seems awfully coincidental that both our POs would have put in 44 jets without reason).

Mine seems to be running good now, but I’m still contemplating trying larger jets. Curious what you ended up doing?

 

Here again we need know what specific carburetor you have in order to determine if jets were swapped.
Carburetor ID stamp location was noted previously.
In 1962/63 there were four 2G’s that came standard with the . 044 main jets.
What year is your 198 ?
1962 had 7020140 or 7020141 main jets . 044
1963 had 7023048 or 702049 main jets .044

 

Mine is a 7023049

 

That should be the latest and greatest 2G that fits the fireball 198 with a standard transmission.