Hi,

I read somewhere that '70 240Z must have engine block casting number "E31" (near the left engine mount), and '71 (and later) must have "P30".
Someone know when exactly it change ?

I have a 12/70 car (serial 17xxx) with "P30" engine block (serial 22xxx) but without engine plate on shock tower. But pretty sure it's the original one.

Thank you for answers 🙂

This may help. 

http://www.xenonzcar.com/s30/engines.html

Unfortunately there's not going to be a clear cut-over date/month.  If you browse through the registries you will see that build dates, VIN, and engine serial numbers do not all align sequentially.  That's the bad news.  The good news is that someone will be able to help with a rough transition timeframe (I do not have that information).

Here is an old discussion that has lots of good info on the subject of engine casting numbers, post #44 is close to yours and is a P30

 

Thank you !
This topic is really interesting (and old 😄 )... But it confirm that my engine must be the original one.
And from what i've read on this topic, the casting number change from E31 to P30 near august or september '70.

👍

For what it's worth I have HLS30-08215, build date 8/70 and it has an E31 block and an E31 head with the 4-screw carbs and the flapper style air cleaner (if anyone reading cases about that info).

I also have HLS30-06293, build date 6/70 and it too has an E31 block and curiously enough it has an E88 head with the 4-screw carbs and the non-flap air cleaner.

I'd have to look at what HLS30-018482, build date 1/71, has since I have no pix of that engine and it's stored elsewhere.

 

As you can see just from what I personally have there's a bit of a mixed bag on the '70s.

My 11/70 with VIN HLS30-15257 has a P30 block (#020294) and a E31 head.