[mcduck]

okay, I've searched high and low and still am not sure what I'm looking at here. Was hoping someone on the forum could identify the head in the picture below. I'm considering buying this motor, but cannot figure out what heads are on it. The casting on the center exhaust port is '50' (not '5c'). The end ports have an 'X' without a number at one end and 'GM3' at the other. It has D-ports and it appears the date code (as you can see in the pic) is H164. I can find no other markings or casting numbers anywhere on the head and cannot find any source online stating what a '50' head is.

Any help is appreciated.

[Pontiac signman]

Both heads say 50? So many times they (Pontiac) cast/stamped #'s off. Probably what your looking at anyway. The 4 at end of date, is either '64 or '74. All heads in '64 or back only fit a '64 or back block. What year is the engine? If block is after '64, the heads are '74 and would be a mis-cast set of 5C's.

Hope that helps!?!

Adam

[mcduck]

it's a '65 block. I was able to verify the block casting.

[Pontiac signman]

I looked back thru my #'s books and, they're 5C's no doubt. No 50, that I can find, were ever cast. Especially looking like those.

5C's!

Adam

[Banshee]

I had a set of 74 "50's" that looked like 50. But they were 5C. Sometimes the casting sand mucked up the numbers. I have a set of pristine 48's and a set of really ugly looking 48's, two sets, cast one day apart. The exterior of the heads on one set look like hell.

[WDCreech]

With a casting date of H164 (August 16, 1964 or 74), they would have been cast for either the 65 or 75 model year. To me, they appear to be 75 heads except for the "5O".

[Fullhouse]

deffinately a '74 head, just look at the shape of the center exhaust port. Just like the 6X head. odds are it's a 5C head

[AdamHoud]

Are 5c heads as good as 4x/6x?

[b-man]

Originally Posted by AdamHoud

Are 5c heads as good as 4x/6x?

Yes.

The 5C heads are pretty much identical to the 6X heads. Both of these are a better choice than the 4X heads, but not by a huge margin.

[WDCreech]

"deffinately a '74 head, just look at the shape of the center exhaust port. Just like the 6X head. odds are it's a 5C head"
__________________
As far as I know, the 5C head wasn't offered in 74!

[gtofreek]

It's a 5C head. As others have stated, you can tell by the shape of the center exhaust port. The casting date makes it made in Aug. of 1974 making it a 75 head which is when the 5C's were used. They had screw in studs, 2.11 intake and 1.66 exhaust valves. 101 cc chambers making a 1978 400 around 7 1/2:1 compression. They would be better for a 455.

[Will]

I concur with others who say they are '74 castings for the '75 model year. The dead giveaway is the extra meat cast at the sides of the center exhaust ports, making a "squarish" casting around the ports. This began in '73 or '74, earlier heads didn't have this.

Funky numbers though, they sure look like "50"...

Check to see if there is a secondary stamping code in the indicated location:

[tikiklubracing]

All the 5C heads

Year Engine HP Engine code Trans CR Cam Head Code BBL Carb No. Misc

1975 350 155 HP YA A 7.6 555 5C 1-2 7045162 Block Casting # 488986
1975 350 155 HP YB A 7.6 555 5C 1-2 7045171 Block Casting # 488986
1975 350 175 HP WN A 7.6 555 5C 1-4 7045269 Block Casting # 488986
1975 350 175 HP YN M 7.6 555 5C 1-4 7045269 Block Casting # 488986
1975 350 175 HP YO M 7.6 555 5C 1-4 7045269 Block Casting # 488986
1975 350 175 HP ZP A 7.6 555 5C 1-4 7045268/568 Block Casting # 488986
1975 400 170 HP YH A 7.6 266 5C 1-2 7045160 Block Casting # 500557
1975 400 170 HP YJ A 7.6 266 5C 1-2 7045161 Block Casting # 500557
1975 400 185 HP WT M 7.6 067 5C 1-4 7045263 Block Casting # 500557
1975 400 185 HP YM A 7.6 066 5C 1-4 7045264 Block Casting # 500557
1975 400 185 HP YS A 7.6 066 5C 1-4 7045274 Block Casting # 500557
1975 400 185 HP YT A 7.6 066 5C 1-4 7045266 Block Casting # 500557
1975 400 185 HP ZT A 7.6 066 5C 1-4 7045564 A.I.R. Block Casting # 500557
1975 455 200 HP YU A 7.6 067 5C 1-4 7045260/562 Block Casting # 500813
1975 455 200 HP YW A 7.6 067 5C 1-4 7045262 Block Casting # 500813
1975 455 200 HP YY A 7.6 067 5C 1-4 7045260/562 Block Casting # 500813
1975 455 200 HP ZU A 7.6 067 5C 1-4 7045562/566 A.I.R.
1975 455 200 HP ZW A 7.6 067 5C 1-4 7045562/566 A.I.R.

[Sirrotica]

If those are indeed 75 or 74 heads....how is it that it has early valve covers on it, as they will not fit without spacers under the gasket ...or at least 2 gaskets stacked on top of each other...if the engine has never been fired ,and there are no spacers or multiple gaskets, the rocker arms will make a row of dimples from the interference of the rocker arms ....been there done that!

[455_regal]

small plugs also== newer year heads