The Ford Barn - Merc 255

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- - Merc 255 (https://www.fordbarn.com/forum/showthread.php?t=333756)

Run the stock 885 with Chevy distributor

I have the 255 with chevy distributor and bosch blue coil, runs very well in my 35

Does the chev distributor come into play only when you are running dual carbs and the sparkomatic does not work with this setup?

Again, I would suggest a Rochester 2G in place of the Holley. It's more modern carburetor than the Holley and a bit larger. It will bolt right on the manifold, but the throttle bores are a bit smaller and the manifold can be bored out to match. Both the Merc's and the 2G's come with either divorced or conventional automatic chokes, so it's just a matter of "mix 'n match" to come up with something that works. The throttle linkage and fuel line fall right into place if you mount the carb backwards on the manifold (believe me, it doesn't care).

"Try it, you'll like it".

Ok, I see we are talking single carb here, so my question is answered.

One 2G flows about as much as 2 94's or 97's. Eliminates the complexities of multiple carbs.

Yes the 2GC works very well in this application. The trick here is to adjust the timing and carb for best AF readungs, It shouls run in the upper14's low 15's milling the heads or increasing the CR with an aftermarket head. Here we tune for mileage. Stock jetting of the 2GC is very close. I have this setup in my truck.
Gramps

What year Rochester 2G do look for &'what vehicles would they have been on

Quote:

Originally Posted by flathead47 (Post 2276000)

What year Rochester 2G do look for &'what vehicles would they have been on

They're beginning to get a little scarce, and pricey. They originally came on the early 265 and 283 Chevys.

Coop

https://th.bing.com/th/id/OIP.VIbY4q...pid=ImgDetMain

The 2GC has a larg & small Units. Not sure of the numbers, however the small one is used on the SBC;s and other small displacement engines
Gramps

The small bore 2G is the one to look for & use on the stock mercury manifold ?
Choke will be manual?
Thanks

Grafting the 2gc carb and accompanying Chevy distributor was the best thing I’ve done to my flathead. I sourced the 2gc carb from Rock Auto rebuilt by UREMCO. Found a nasty one for $50 for the core charge. The manifold I had was for a carb with choke, it had the heat tube running through the exhaust crossover. Had some initial teething problems with the carb and had to send it back to UREMCO but they were great to work with. It’s almost unbelievable how much difference this made. The engine is so eager and smooth.

To re-iterate: The carb must be a small base version (the large base versions are just enough different so they don't fit.) The Chevrolet carburetors have a side mounted fuel inlet, and the throttle and fuel lines will almost fall into place if the carb is mounted backwards. Trust me, it doesn't know the difference. I have several of these setups and they all have automatic chokes. If you match the choke type and carburetor choke types, the choke systems are compatible as well. Both the Rochester carburetor and Mercury manifolds come with either divorced (mechanism on the manifold) and regular (mechanism on the carb) automatic chokes. Either takes a minor tweak of the actuating rod or heat tube to fit. If in good shape, both are easy to adjust and work fine. I am usually a "manual choke guy", but the automatics fit so well and work so well, that I gave in.

There are a couple of other things to consider. While the small base 2G will bolt right on to the Mercury manifold, there is a mismatch in the throttle bore sizes. The carb is 1 7/16" while the manifold is 1 1/4". While the carb can be used as is, it is better to match the manifold to the carb. It can either be "bell-mouthed" or bored out all the way down (the method I use). There is plenty of "meat" in the casting as I have never had a problem. I have done both cast iron and aluminum manifolds and both cut easily. Also, there are heat channels in the base of the 2G that can cause vacuum leaks. I make a 1/16" aluminum plate that sandwiches between the Merc and Chevrolet gaskets that solves this problem.

Thanks for all the great info on this setup.
Is a picture available to show the final result.