B18 engine 3 digits serial number?
 

Hello friends

Checking my engine serial number today I discovered that is not the original engine with what the car was delivered in April 1962 (Volvo Museum info in Sweden), and that the serial number installed has only three digits.
I neglected to get the number on the first machined plate before the serial number and after 4968
The serial number showing 351, which looks strange, but what do I know?
Have any of you seen such a small number before?
Happy Easter to everybody
Andres

Now I have the following numbers in the sequence 4968 69 351, if I understand correctly the list published in https://www.scandcar.com/motortypen-volvo/ this will make the engine a 115 HP originally from an automatic Amazon.

Will appreciate your comments

Best

Andres

That looks to be correct. That's a very useful list. That engine spec is the highest available, also in the 123GT and the 1800 models. High compression and C camshaft. The high CR means that you really need to use the highest octane gas you can find. Even then it will be lower than what was available at the time, which was 100/101 here in Europe. Pinking/pinging can be a problem unless you retard the ignition by a couple of degrees or so. Retard as little as possible or you will start to feel the reduction in power if you use the whole rev range.

Thank you Derek. I have access to AVGAS (aviation) 110 octane low lead, in your opinion would that work? the better gas available in Mexico is only 92 octane
Cheers
Andres

USA octane ratings (PON) are different from those used in Europe (RON)
Your 92 is roughly equal to 97 here. That's not too different from the old 100 and there have been some improvements in the fuels since the 60's. Of course, fuel had lead in then which is used to stop pinking among other useful benefits. I don't know the specs of the 110 AVGAS. Racers might use it so they could use very high compression ratios but I don't think I would consider it for general road use. Adding a couple of litres to a tank might give you a bit of a boost but that's up to you.