Thats what I said, H low riser and the G came on 390s AS WELL 427, both yes are low risers and BOTH SUCK....No they donot have the same vals as a 428 cj. The plain 428 7 liter that came in a galaxie had them both G and H from factory depending on which set on assembly line a factory worker picked up , both still suck. I just sold a 406 G code with 3 duces. That engine had same vals as a 428 cj near touching. All are fine on pump gas for all 4 sets we are describing came as a factory head. The G head and H BOTH have smaller vals than a 428 cj. I got a barn full of R and H . They sell for 200 bucks or less. Cj with big vals clean and ready to go sell for 900 to 1200 bucks. The 406 G code engine which came with 3 duces had the C heads. The 406 B code engine with 1 4 barrel came with the B heads. As far as a 427 with low rise heads , that engine will only turn around 5500 before it starts to break down. You can take a 390 engine with the cj heads and spank a 427 low riser engine on any day. Now you can place the cj vals and stronger springs on the G and H head and do alittle work they will run as good as the cj heads if you do a val job and add stronger springs. The H and G heads ......smaller vals, weaker springs and will not stang high rpms
Wrong again.
The C3AE 6090 G and H only came on the 427. 427 LR heads have slightly wider valve spacing, but do have CJ size valves, 2.08x1.64.
390 Heads only had 2.02x1.55 valves. Maybe you are confused with the C4AE 6090 G which was a 390 head with small valves.
I can guarantee that the C3AE 6090 G or H did not come on a 7 litre/428 Galaxie, since they weren't built in 63. The heads did not keep the engineering numbers or suffix from year to year. A C4AE-G, C7AE-A or C8AE-H like the 428 passenger cars came with were just a 390 head with small valves. This has absolutely nothing to do with the C3 part number.
The C3AE 6090 C head that came on the 406 you are talking about only has 2.02x1.64 valves. The small 56cc chamber will raise the compression about 1.5 points over your normal LR 72cc heads. You also have to account for the different compression heights of the pistons. Ford did have 3 versions of that head though, including one with a 64cc chamber and small valves for higher altitiude, and a standard 390 head... one of Fords many engineering number screw ups.
The earlier 406 heads had the same size valves as the 390, but higher compression, bigger cams, and better carbs bumped the HP numbers significantly.
Keep in mind that the 63/64 427 LR had about 11.5 to 1 CR with 72 cc chambers. If you put 56cc 406 heads on it that would jump up over 13 to 1...good luck with pump gas.