Police Carburetor for 255 Merc
- Thread starter Mikes ‘53
- Start date
tubman
Well-known member
I just looked at the eBay offering for that carburetor. Forget the "Mercury Police" BS, because that's a complete fantasy The carburetor listed appears to be a "garden variety" Holley 94 used on all Fords of that era. ALL Mercury's used a larger 4 bolt Holley carburetor with 1 3/8" throttle bores (the Ford carburetor is smaller (I think 15/16"). The first thing you should do is get the proper Mercury 4 bolt intake manifold and the correct factory carb. There is no amount of boring or grinding to open up the Ford manifold even close to the Mercury unit. An even better solution would be to bore the Mercury manifold to 1 7/16" and get yourself a small base 2G off of a 283 Chevrolet.Mikes ‘53;2448726 said:
There is a good reason for using Ford heads on a Merc, as the Ford heads have a slightly smaller combustion chamber year for year as the Mercury's because of the shorter stroke. This will raise the compression of the Mercury slightly. There is absolutely no good reason to go to the 3 bolt Ford manifold and carburetor on a Mercury, as the flow will be considerably reduced. With all of those Ford parts on the engine, I would have doubts that it is even a Merc. Short of measuring the stroke or looking at the crankshaft closely, there is really no way to tell. The actual color of the block (if the original paint) can be indicative, and there are a couple of small details that might be telling, but none are definite.
Good luck.
rotorwrench
Well-known member
If a person uses any carb other than one for the Holley load-o-matic distributor, they will either need an old Mallory mechanical advance type or a modified GM or other distributor set up for the flathead.
The old Mercury 885 or later towering inferno types aren't bad carbs but most have already been damaged by shade tree mechanics. They have a complicated power valve systems that rely on good vacuum signals to work well. They get warped and can leak fuel or vacuum but they do work with the old distributor.
The old Mercury 885 or later towering inferno types aren't bad carbs but most have already been damaged by shade tree mechanics. They have a complicated power valve systems that rely on good vacuum signals to work well. They get warped and can leak fuel or vacuum but they do work with the old distributor.