[SBCfan04]

on the side of my 400 it says 010 and 509 what do these mean?

[justacertifiedtech]

Are these numbers cast into the block (raised numbers that were formed when the engine block was made in the mold) or are they stamped into the block (recessed)
Also what year is your engine and what is it out of originally?

[curtis73]

they mean very little. The common thought is that it has to do with casting alloys, but its been shown that different alloys were used in the same molds over the years. The more important numbers are the casting number at the rear and the stamping number in front of the passenger side head.

[justacertifiedtech]

As curtis said they mean very little as far as the 509, not sure maybe alloys?
If there are any letters before the 010 it is possible it is a date code for when the block was cast.

[SBCfan04]

Originally Posted by justacertifiedtech

Are these numbers cast into the block (raised numbers that were formed when the engine block was made in the mold) or are they stamped into the block (recessed)
Also what year is your engine and what is it out of originally?

these are the cast #s on the side of the block but the engine year is a 1978

[justacertifiedtech]

Ok you got me wondering so I've been doing a little research what I've found is these numbers are usually under the timing cover but I have found some occurences of them being cast into the side as well.
When under the T-cover you will usually find 010 AND 020 this indicates metalurgy 010 = an extra 1% tin added to the metal in the block
020 = an extra 2% nickel added which makes these blocks stronger
The 509 is for the 2 bolt main 400 which is actually better than a 4 bolt.
It seems the outer 2 main bearing bolts on the 4 bolts cause weakness in the block.
The main thing I have found is this is what you want to see for your casting #

[RippinRon]

Originally Posted by justacertifiedtech

Ok you got me wondering so I've been doing a little research what I've found is these numbers are usually under the timing cover but I have found some occurences of them being cast into the side as well.
When under the T-cover you will usually find 010 AND 020 this indicates metalurgy 010 = an extra 1% tin added to the metal in the block
020 = an extra 2% nickel added which makes these blocks stronger
The 509 is for the 2 bolt main 400 which is actually better than a 4 bolt.
It seems the outer 2 main bearing bolts on the 4 bolts cause weakness in the block.
The main thing I have found is this is what you want to see for your casting #

Do a search on this site regarding the 010 myth!

[SBCfan04]

that sounds right cause the block is a 2 bolt 400

[curtis73]

Originally Posted by SBCfan04

that sounds right cause the block is a 2 bolt 400

True... but the 010 casting number that denotes the 4-bolt 350 ONLY applies to the casting number of the block found on the bellhousing flange. The 010 alloy number on the side doesn't mean its an 010 casting.

What I'm saying is, the 010 on the side can imply an alloy without any bearing on the actual engine's designation.

But, like has been said, the alloy number on the side doesn't necessarily mean squat.

[curtis73]

Originally Posted by justacertifiedtech

When under the T-cover you will usually find 010 AND 020 this indicates metalurgy 010 = an extra 1% tin added to the metal in the block
020 = an extra 2% nickel added which makes these blocks stronger

Friendly ammendment... additional nickel makes the block harder, not stronger. Harder is great for endurance, but it can mean more resonance in high RPM applications.

Harder isn't necessarily better like everyone seems to think.

And as a sidenote, tin is added to the alloy to help it flow better into the mold.