Early Mercury block vs 59A

Ok so one can say the ’early’ was 39 and they called 99 or 99T ( but what did the 1940 called ? )
As 1939 was the first 100 HP and 24 stud.
Better material, thickness, who knows but the story goes on..
And one can see a 99 block as no rised intake surface and bulps on outside the lower part on block as 4 plugs in the oilpan rail.
The 41 blocks had no plugs but rised intake but this blocks 39/42 is squared so the ’same’ family.

-My only question now… what was the 1940 named ?
 
My understanding is a 1939 221 is a 91A, a 39 merc is a 99A, a 40 221 would be an 01A, whereas a 40 merc would be an 09A, a 41 merc is a 19A etc. The first number is the last number in year of manufacture, the second number is the last number of engine displacement. so, 1939 [9] and 221 [1], is 91, whereas 1939 239 is 99. etc....The Canadian blocks have these numbers cast into them on the sloping face in front of Number 1 cylinder.....American blocks don't carry these identifying details to the best of my knowledge. Somewhere on this site, someone has posted a thread that allows identification of all blocks cast from 1932 onwards.
 
Canadian ?
 

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As Brian noted, I've only see the casting letters on Canadian blocks, though I have no clue as to if any were cast in Europe at the time and what nomenclature they would have had. So, the above block appears to be a 39 Canadian block, 239 cubes. Given the factory relief, it may have come out of an industrial application or truck.

I'm not 100% sure, but my guess is that the factory relief was not used for passenger cars - though this is just a wild-*** guess! LOL
 
Bored&Stroked said:
As Brian noted, I've only see the casting letters on Canadian blocks, though I have no clue as to if any were cast in Europe at the time and what nomenclature they would have had. So, the above block appears to be a 39 Canadian block, 239 cubes. Given the factory relief, it may have come out of an industrial application or truck.

I'm not 100% sure, but my guess is that the factory relief was not used for passenger cars - though this is just a wild-*** guess! LOL
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This is my understanding as well. I read somewhere that the factory relieve was an attempt to stop the cracking at the valve seats. Fact or fiction, I'm not sure for I have relieved and non-relieved 99A's that are cracked at the #3 intake.
 
Thank's guys.
Very good info.
One can say this 39 to 42 Mercury block is the same family.
It's no indicatuion the 'early' ( say 39 ) was any better than ex 41/42 or the 59A block's aswell, more than rumors.
For me it is just intresting information good to know as historical aspects.
I will soon has 3 of 1941 block's.

What is the cast number back/upper part on block on 1941, if I get it correct 19A (?)
 
3W Hank said:
Thank's guys.
Very good info.
One can say this 39 to 42 Mercury block is the same family.
It's no indicatuion the 'early' ( say 39 ) was any better than ex 41/42 or the 59A block's aswell, more than rumors.
For me it is just intresting information good to know as historical aspects.
I will soon has 3 of 1941 block's.

What is the cast number back/upper part on block on 1941, if I get it correct 19A (?)
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I don’t believe there are any meaningful numbers on the back of a 41 block US or Canadian.
It also appears to me that there are 2 families of blocks 39-41 with and without pan rail plugs Possibly 3 if you add in the raised intake rail. Canadian and US blocks being different.
So my 19 ( making it a 41 Merc) Canadian block has 4 pan rail plugs no raised intake.
 
I shore has the 41 block's as no plugs and rised intake on them.

-What I mean on same family was the tringle top, round centre and the trapazoidal lower water channel in deck ( Mercury )

I'm shore would like a 1939 block but I'm Ok as this is early Mercurys.
In big picture one is Ok if one find a FH block that is Ok, no matter of model/year..
 
Here is what my block looks like (after just a bit of work). It has the raised area (or one could say "lowered block") on the intake and no core-plugs in the pan rail:

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Tim Ayers said:
Dang, Dale. Beautiful. How deep are your reliefs? I'm going to tackle this on my next build.
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This block has what I'll call an "experimental relief" . . . it mimics some reliefs that I've seen on some Harley KR jugs. It is about .187 deep (at the deepest) and it has a ridge that you can see toward the exhaust side.

When I built this motor I used it as an experimental mule for a lot of ideas that I wanted to try on the street.

a) Ceramic coated pistons and valves
b) Harley KR relief (based on some KR racing engines my neighbor built).
c) MLS head gaskets
d) Custom pistons -> top ring moved down, shortened pin
e) Big *** roller cam with 280 degrees of duration at .050 and .420 lift.
f) Stroked and nitrided Merc crank
g) 1.72 intake valves and very heavy porting of the block and the intake.
h) 12 lb billet aluminum flywheel.

It only has two Stromberg 48's on it currently, though I plan to put a 4-carb Edelbrock manifold with four 48's on it just to see what it does. Now, if I can just complete my new shop building . . . then I'll be back to my various (too many!) projects! LOL
 
I posted the ad for the 39 Merc, after doing some cleaning & some opinions from people smarter than myself I pulled the ad, I should have gone the extra mile before posting . bad pitting around a couple of valve seats . Sad put the block is going to scrap.
 
flathead48 said:
I posted the ad for the 39 Merc, after doing some cleaning & some opinions from people smarter than myself I pulled the ad, I should have gone the extra mile before posting . bad pitting around a couple of valve seats . Sad put the block is going to scrap.
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Don't be so hasty. Usable blocks (especially these) are getting hard to find and expensive. From what I can see, the right bank looks OK. How about posting some pictures of the left bank so we can judge for ourselves? Maybe even a couple of close-ups of both banks.
 
Worst can be than some pittings.
Dont throw it, I pick it up ( from Sweden..
Its a Merc bloc and not 41/42.
 
Remember this block has not been pressure tested
 

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