I was looking for some information and found foreverpontiac, so I joined.

I have 3 Pontiacs and was looking for information on cylinder heads casting number I can not find anywhere.

The heads have been on my 70 tempest for years I bought them from a machine shop in the late 1980’s. They have 218 on the center port and c147 date code.

I don’t have an answer but figured I’d welcome you and state those are some fine Pontiacs you have!

RichE - welcome to FP and the madness. 
 

There are no 218 heads that I can find. The only 200 series cast heads I know of are the 214, 215, and 216. These were mounted to 400 engines. All three have 72 cc chambers, 2.11” intake, and  1.77” exhaust.

Another possibility is these are really #18 heads, cast with a 2 in front. If this is the case, then that’s a different animal. The #18 was the 350 HO head for 1968. 1.96” intake, 1.66 exhaust and 66 cc  chambers.

c147 is the casting date - March 14, 1967

I find this interesting because the 18, 214, 215, and 216 heads are all 1968 model year only heads. So it begs the question, in my mind at least, did Pontiac start casting 1968 engines and/or parts while in the middle of the 67 model year? I would have expected a summer or early fall date for start of production of new 1968 heads, which is the usual model change over time frame.

You didn’t mention in your introduction what size motor you have in your Tempest. A 350 engine would be common in a Tempest as the base V8.

Edited February 27, 20251 yr by Frosty

Welcome!  Chat it up with us in the forums, jump in anywhere and share your knowledge with the rest of us!

Frosty, I have had these heads on my 1970 tempest since about 1989 and they have worked out great. The car was originally a 250 6 cylinder I put a 1973 400 out of a Catalina in 1986. I took the original heads to a machine shop to have a valve job done during a  rebuild and I ended up exchanging them for the 218 heads.  Over the years I have tried to identify them and have found some of the info you shared.

One of the things that seems odd is the “8” in 218 being larger than the “21”, I do not recall seeing that before.

The engine was rebuilt in 1989 with one of the kits from Performance Automotive Wharehouse. It’s has 0.030 cast pistons the 218 heads,  a melling ram air 3 cam, 1968 manifold with Quadra jet and exhaust manifolds.  
 

I am going to remove the engine to reseal it and clean this spring and it brought the question of these heads up again.

I appreciate the back story. I would recommend measuring the valves and take a wire  brush to the casting numbers to clean up any scale or rust, and make sure the 8 is an 8 and not a badly casted 6.

Right now I am of the opinion that this is a #18 head. In some of the other forums I read, Pontiac did, probably by accident, cast #14 and #15 heads with a 2 in front. No one knows why.