Mercury Crank casting #'s?

Johnny-B-Bad

Johnny-B-Bad

Senior Member
WEll ive got a stuck flatty that came out of a 53 ford i bought and im looking to see if i have a mercury crank in it because it had the 8CM heads on it. Looks like the motor has been rebuilt before. Are there any casting numbers i can look at to identify the crank? I found the number of 023 cast into it but im not sure if that means anything. Thanks, John. Oh and the motor is stuck so i cant check the stroke.
 
Johnny-B-Bad said:
WEll ive got a stuck flatty that came out of a 53 ford i bought and im looking to see if i have a mercury crank in it because it had the 8CM heads on it. Looks like the motor has been rebuilt before. Are there any casting numbers i can look at to identify the crank? I found the number of 023 cast into it but im not sure if that means anything. Thanks, John. Oh and the motor is stuck so i cant check the stroke.
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John, the Merc crank will have 1CM on one of the counter weights, and 5/8th cleanout plugs....Ed
 
This will draw some comment but SOME 1CM cranks are CAST steel instead of cast iron.
The easiest way to determine this is by the spark test.
The most positive way is quanitative analysis.
The steel cranks are more desirable for racing and making into welded
strokers.
They are absolutely NOT required for street use.
So far as I have been able to find out, there is NO Ford documentation
on why they made both steel and iron cranks.
I had several analyized and some are definetly steel.
 
When touched to a grinding wheel, different materials give off different color and different shaped spark patterns.
 
Although I've been in this discussion in the past, I won't comment on that. I will say that Ford went to a shell molded crank in 53 and this was made from Nodular iron as most cranks are made of today.
 
34fivewindow said:
John, the Merc crank will have 1CM on one of the counter weights, and 5/8th cleanout plugs....Ed
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Ed:

Like all things Ford, most but not 4" cranks are like this. I have a 4" Canadian crank from a bus that is definately 4", has the kindney bean "dimple" on the first weight, and uses the smaller 3/8ths?? clean-outs. Yet another mystery to the Ford flathead.

The quickest and most reliable why I've spotted them is by measuring the large counter weight length.

(I'm going off memory here so bear with me. I think this is correct :)) If it is just over 6" at the widest point, could chance it is a 4" crank. If it is about 5 3/4", it is the a 3 3/4 crank.

Tim
 
lucky said:
What is spark test?

thanks, marvin
Click to expand...

Put a red stone is a die grinder.
Lean into a counterweight with it.
If the sparks are dark red with no sparkles, it is iron.
If the sparks are bright yellow with sparkles, it is steel.
 
Pete is correct; I own a steel Merc crank that has subsequently been offset ground to 4 1/8. Most definitely steel! Brian
 
And only some Merc cranks will have the 1CM (1951 Merc) designation...the big change rquiring the mark was a pilot recess in the back that accepted a protrusion on the coupling for the new automatic transmissions. The change did not affect use on standard trans.
 
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