I need an engine identification. I took the passenger side valve cover off and found the casting numbers, which are 571870 with the number 4 on top of it and #16 heads. The pad on the driver's side has A1 31506 on it. Is this a 1957 original 371 engine in the car? thank you in advance

 

I believe the 1957 heads were #14. 1958 heads were #16's. You may not be looking for the casting number in the right place.

 

im open to suggestions in where to look. what are the numbers i found do you know ?

 

The casting number 571870 is consistent with a '57 or '58 cylinder head.
The '57 head will have straight valve springs and the '58 will have "beehive" valve springs

 

Here is a picture where to look,
https://www.google.com/search?client...er+heads#pvs=0
Scroll down to "People Also Ask" and click on the first one.

 

i have straight valve springs, i have my work cut out for me. This engine is a slug monster.

 

I just checked, and i do have #16 heads on both sides

 

Whats a "Slug monster" ?

I was told #14 heads on the 1957's had a tendency to crack. #16's were 1958. Unless you are building a "Con Cours" restoration, use the heads you have.

 

any idea what # A1 31506 is on the driver side pad ?

 

That's the engine unit number.
1957 Oldsmobile engines had an "A" prefix.
https://www.classyco.com/oldsmobile/...l-information/

 

thank you that link was very helpful

 

Thank you Charlie. That indicates to me that #16 heads were also used on 1957's.

 

i appreciate everyone's help

 

Since the #14 heads were cracking, #16 heads may have been developed in order to correct this problem.
It's possible that later production '57's may have been built with the #16 head. And that warranty replacements were also #16 heads, and replaced in pairs..

 

Charlie, my previous information was from an Olds supervisor in the paint shop. I am thinking they redesigned the head cores because of the cracking problem and started using them in 1957, and they were service replacemnts.

Whats funny, NHRA listed the 1957 heads having 72 cc combustion chamber volume and 1958 heads were 75 cc's. 1957 used a different thickness head gasket than 1958. According to NHRA.

I am heading up north to my land this week. I'll be taking pics of the cowl tags and serial numbers on my '49 and '57. I'll also check head numbers on the '57.

 

thanks cant wait to see them. this is all great info