I've been wondering wheter the engine on my 74 Z28 is the original or not, I started to unbolt manifolds, heads etc.

I've noticed that on the area just above the oil filter it reads ;
10
20
and a three digit number. I know that 10 20 means something. Is it good news or bad news ? What does 10 20 means ?

I've checked the engine code suffix and seen a disappointing CE43 code. If I'm not mistaken block casting date code is on the driver's side at the rear of the engine, near to casting code. There I've only seen a "3" nothing more. The block is a 3970010 casting.
Casting date code on the driver's side head is matching the car's build date and has 2.02 valves. I think that the block is a warranty engine block cast on 1973. Do you have anything to add ?

3970010 were all higher nickel content blocks (i.e. tougher than others without raised nickel content)- under the timing cover you will have the numbers indicating the actual iron mix (i.e. percentage of nickel content)- but I'm not sure what the "10 20" above oil filter is all about- perhaps some blocks got stamped in both places?

Either way- I'll move this to numbers decoding where the real experts on this sorta thing hang out...

The 10/20 means this block is cast with 10% tin and 20% nickel.

This being a warranty job, I guess the dealer didn't want to fix it a 2nd time.

If you were asking what the CE43 means I can tell you.

Actually there should be 4 more digits after the 3.

CE - Chevrolet Engine (Service replacement)
4 - Means this engine was manf. for use in the 1974 model year
3???? - is the engine serial number. Numbers in the 20000 to 49999 range are engines built for Chevy at Flint V8 engine plant

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Mike

2002 Trans AM WS6 build #3124 - Pewter
2001 GMC Ext Cab SLT Z71 - Green

[This message has been edited by WS6 (edited August 08, 2003).]

Thank you WS6. You cleared a huge lot of matters for me.

The engine is, indeed, in a 74 Z28.

One other thing to note.

A 'CE' coded engine was not necessarily a complete engine. It was what they call a short block, a new fitted block with crank, pistons,cam etc. They would reuse the heads, and all other external parts from the original engine if they were salvageable. Rarely would the install a complete engine. No need to replace good parts.

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Mike

2002 Trans AM WS6 build #3124 - Pewter
2001 GMC Ext Cab SLT Z71 - Green

That is the case in my car, I think. They only replaced the block not the other components.

Today I've checked the engine again, and saw that it reads CE4318 as engine suffix stamping.