identify this motor

[thetrailergod]

can anyone identify this block?? casting# 831-4989 serial# 8577443, notice the extra boss on the side of # 2

[mr2boats]

Looks like a merc 500 squish style block

[David_L6]

That's a Merc 500. A 44. An E Mod in NBRA, a D Stock and D Mod in APBA.

I know where there are a couple of those in stock form.

I also know where there is one of those in a highly modified form.

[thetrailergod]

i know its a 44 but have never seen the xtra boss on the side of #2 like this , I have 7 500 blocks here in the garage, none have this boss on it, maybe a Belgum or Canada engine?? also as old as it is and very run it still has 145# compression on all 4 cyls

[David_L6]

I don't think it's anything all that uncommon. As I said in my previous post, I know where 3 of those blocks are.

[STEVE FRENCH]

Dave Scott.....Would this be the "Classic" powerhead?

[Sonny]

I have wondered exactly the same thing. I bought a offset plug 500 motor a few months ago it is a blue band motor...1974 I think, and it has that boss on #2 cylinder...I have seen a few of these done up as "D" mods and wondered what the significance of the boss was. I would love to know also if anyone has any insite on the matter.

[trident]

Casting Boss

Garden variety Merc 500. No significance... they made 'em that way for a while. A place to stamp numbers. Nothing different inside.

They also made them with various oiler bosses at top bearing cap.

Obviously, tooling got updated periodically, as they made jillions of these
44's.

I ran several of these blocks, back in the day...

The classic, as in 'Classic 50' is a much newer block with the four coil CDI, no fuel pump bosses for the horshoe pump and different top bearing cap.

BTW, to you guys running these type blocks, note they were made with two different depth spark plug holes. This is on the offset plug hole blocks. Early were machined for J reach plugs, later they were made to fit L reach plugs. Just be aware, so you get right plugs. Hammered electrodes don't fire well.

Hope this helps.

Jerry

[mercguy]

I have wondered exactly the same thing. I bought a offset plug 500 motor a few months ago it is a blue band motor...1974 I think, and it has that boss on #2 cylinder...I have seen a few of these done up as "D" mods and wondered what the significance of the boss was. I would love to know also if anyone has any insite on the matter.

the boss was just added to allow Merc a place to stamp the serial number so it could be easily seen and read..................nothing special......

[DUNN RACING 10-Z]

I think it is a '72 or '73 block. The only blocks like that had lightning energizer ignition.