8ba flat head

[richard crow]

how can you tell if it,s a mercury eng with out taking it apart

[petehoovie]

8CM on the heads would be the first clue....See > https://www.jalopyjournal.com/forum/...athead.341885/

[Bored&Stroked]

If the engine is a 49-53, then it can be a Ford or a Mercury engine - the blocks are all the same. The factory heads for Mercury were marked 8CM, though people have swapped all sorts of parts back/forth between Ford and Mercury engines.

Unless you pull a head (to manually measure the stroke - assuming the engine can be manually turned over) or pull the pan, no way to know that you have a Mercury 4" stroke crankshaft or not.

[flatjack9]

Also EAC Mercury heads.

[tubman]

Mercury's used 4-bolt carburetors rather than the three-bolt Holley 94's used on Fords. Heads were more likely swapped, as Ford heads give more compression if installed on the longer stroke Mercury engine, while swapping to a smaller carburetor would be less likely. Plus Mercury manifolds are a lot harder to find than Ford heads.

One other thing that may help is the shape of the brass fitting at the inlet of the oil filter. I put a '51 Merc engine in my '51 Ford a couple of years ago. The Ford engine (which I am sure was original to the car) had a square "blocky-looking" fitting, while the Mercury had a rounded fitting more like a conventional pipe fitting. One last thing; if the engine is out of the car and you can see the oil pump gear cover, it may tell you something. My Ford had a stamped steel cover, while the Mercury had a cast cover.

I know a sample size of one is hardly indicative, but this is what I have seen.

[51504bat]

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Depending on the year Mercs had water pumps (both wide and narrow belt configs) that on first look appeared to be like an 8rt truck pump but the mounting pad on the pumps is higher requiring either a u shaped spacer or on the early wide belt years the spacer was more like a square block. Most true Mercs (don't know about the later years) had a stamped steel 1/2 bell and a rear sump oil pan. All this really means nothing without measuring the stroke. I once bought what was purported to be a Merc that had Merc heads, Merc pumps, and a Merc 1/2 stamped steel bell housing only to find it had a 3 3/4 crank not a 4 inch. Photos show the 2 different types of Merc only pumps and a Merc 1/2 stamped steel bell housing.