Unusual carburation on Flathead V8’s

[51 MERC-CT]

Originally Posted by Merc Cruzer

RalphM,

How much modification to replace the 9510 Teapot? What model Rochester? Would it work with the distributor found on the 53' Merc with a Merc-O-Matic?

Originally Posted by RalphM

I would think it would just be a matter of swapping the intakes on the 53, should have enough vacuum for the dist, but I’ve never tried it.
I’ve never used this setup before, but I’d like to give it a go.

Unless whatever carb you put on it has provision for a venturi vacuum source, the stock distributor will not work correctly as I understand it.

[Ol' Ron]

I tink the Weber is a direct bolt on to the flathead. The reason is Kenny Web ran one at Danbury and the rules stated that you could run any carb that bolted on the stock intake.

[cadillac512]

Rochester 2GV on a '50's Merc 4 bolt manifold. As tubman said,the carb mounts backward and the linkage lines up nicely. This carb is from a late '60's Chev.



As for any carb other than stock working with the late flathead distributor, that's going to be a no-go. The stock load-a-matic distributor used a combination of venturi and manifold vacuum sourced from unique drillings in the stock carb. Ported vac will not work properly and neither will full manifold vac. A distributor swap will be needed to make things right.



Terry

[Merc Cruzer]

Originally Posted by cadillac512

Rochester 2GV on a '50's Merc 4 bolt manifold. As tubman said,the carb mounts backward and the linkage lines up nicely. This carb is from a late '60's Chev.



As for any carb other than stock working with the late flathead distributor, that's going to be a no-go. The stock load-a-matic distributor used a combination of venturi and manifold vacuum sourced from unique drillings in the stock carb. Ported vac will not work properly and neither will full manifold vac. A distributor swap will be needed to make things right.



Terry

Thank you, for the explanation.

[tubman]

Just a side note. While a small base Rochester 2G will bolt directly on to a Mercury manifold, the throttle bores in the manifold are smaller than the carburetor (1 5/i6" vs. 1 7/16"). I bore the manifolds to 1 7/16" all the way down with a "Rota-Broach" using a special guide I made. As mentioned above, the throttle linkage and fuel line are positioned correctly if the carburetor is mounted backwards. Unfortunately, this puts the manual choke in the wrong position. However, the Mercury automatic choke mechanism is positioned exactly right for use with a 2G. I have done both the on-carb choke (2GC with an early manifold) and the divorced choke version (2GV on a later manifold) and both require only minor modifications to make them work.

And of course, all of this precludes using the original distributor.