Technical Nailhead Info Needed

I have a 401 Nailhead 4 barrel engine in my current 32-5W project and I am looking for some info on this engine from the Buick experts on the HAMB.
On the top front of the engine block, US drivers side facing forward is the number 812008803 and on the p***enger side facing the driver is stamped 4I181314
Would appreciate if someone could explain these numbers to me.

 

812008803 is the engine serial number. The other numbers- 4I translates into a 401 4V engine built in 1962 and the rest of the numbers would match the vehicle VIN number the original engine was in. There is also a block casting number on the block behind the distributor that gives more info.

 

Thanks for that @Bangingoldtin. I will get the block casting number when I get out in the shed tomorrow morning and post it on here.

 

Found the block casting number just where you said it would be @Bangingoldtin and it's 12/21 Hope you can tell me what it means. Thanks

 

There should be a block casting number there starting with a one. 401 engines used the casting numbers 1185404, 1185484, 1345404, 1346046, 1349046, and 1364714 in those years. The 12/21 would be the foundry casting date of December 21st.
There are also casting numbers on each head between the two center spark plugs.

 

OK I will check it out tomorrow. Not easy as there is not much room between the back of the engine and the firewall.
Numbers off the heads should be easy, will get them too.

 

OK @Bangingoldtin you were correct and I found the block casting number and it matches one of the numbers you posted i.e 1349046-3 and the number on one of the heads was 1196914
What info on the engine do these numbers provide?

 

The block number is a '62-'66 401, and the head number is for all engines from '63-'66.

 

Thanks for that @HEATHEN as that ties in with the engine number but it looks like the heads have been changed as the engine came out of a 62 model car but things could have happened before it arrived in Australia.
Would the casting number on both heads be the same as I have plug wire covers on one side and I never pulled them to check that side?

 

@HEATHEN is correct. The block is a 401-engine casting used from 1962 until the end of production in 1966. The head casting was used on 364,401,and 425 engines from 1959-66. That casting number is a**** several, but is the one most seen. Going back to your 4I181314 number- because it does not have an L in front of it, or an X at the end, it was a standard bore 401 with 10.25 to 1 compression. The L would indicate a low compression motor, and an X would indicate that it came from the ***embly plant with an .010 overbore.
It came originally with a steel shim head gasket, and although a fairly aggressive cam, it had been toned down some from the earlier motors.

 

That head casting number (1196914) is correct for a 1962 motor. I have a 61 364 and a 64 401 with those heads.

 

Thanks heaps for your help @Bangingoldtin and @HEATHEN as I now know a lot more about the engine in my project. With the 10.25 compression should I be running a high octane fuel. We have 91, 95 and 98 available (ignoring the ethanol stuff) so which one would you recommend?

 

Although Buick advertised the compression at 10.25, it rarely was that. Your actual compression may be lower if any engine work was done (such as the steel head gaskets replaced with layered ones). Because of the unique quench design, you can get by with lower octane. It should run fine with 91.