I've decided to pick up some Yates heads for my turbo car, since they seem to be available all over the place due to the race teams selling off old NASCAR and Cup car stuff. This used stuff seems to be a fairy reasonable way to make huge power. It's not cheap by the time you get it all together, but it is inexpensive for the amount of power you can make.
I've searched all over and didn't find a good list of the different stuff out there, so I figured I'd make a post and update it as I find more information. I'll try to update any time I get new info. If anyone has anything to add, please post up or PM me what you know about the different ones available out there.
The casting numbers on Yates C3 heads are most often E3ZM 6049 C3. For some reason, they used this same number for 30 years, even while changing the castings quite a bit. Some of the early C302 heads have that same number on them, so make sure you figure out what you're buying.
The latest standard C3 castings I've found are dated 2002. This doesn't include the C3H (High Port - Raised Intake Ports) or D3 versions. The 2002 castings I've found use one-piece rocker stands and have Beryllium copper valve seats which are "figure eight" style, meaning the intake and exhaust seats are one piece. This is desirable because it adds strength and durability to the thin area between the valves which is helpful for extreme uses. The port design is said to be better than the previous version.
The 1999-2000 C3 castings are said to be identical to each other, and sometimes pairs of heads will have one of each. These heads also use one-piece rocker stands, but they don't seem to have the "figure eight" valve seats.
You can tell the 99 and newer casting by looking at the head bolt holes under the rocker area. New heads the bolt hole is a complete circle around the Bolt head and the older ones this area is open around(or the sides) of the bolt heads. (this info from twinturbojunk on the bullet)
The C3 castings from the mid 90s seem to always use separate rocker stands, although many race teams have welded them all together for strength. These heads don't use the "figure eight" valve seats either. The ports are still said to work well, but not as well as the later versions.
The very early C3 heads have canted valves and use Cleveland rockers. They used the same M-6049-C3 part number as the C302B heads and were based on the C302B. Dan Jones' post below states that the cant angle of the valves were removed to allow for smaller chambers. The A head , the Cleveland, C302 & C302B head is canted..& some others.. If you have a 6049 C3 <ending part number and it is truely canted then it is a very early head... Ford ended the cant on the C3 in 1991 but some C302's had the C3 part number this is a confusing subject and has been for years.. Normally the C3 will not fit onto a cleveland bc of the pistons for the canted valve , althought the C302 will. (This info from Jason Eaves on the
www.yellowbullet.com)
Most of this old cup car stuff seems to come with titanium valves and Jesel rockers. Chamber size seems to range from 50cc-39cc on these heads. The C3L and C3H Yates heads are said to come with 67cc chambers.
The C3H “High-Port” is similar to the standard C3 casting but has raised intake runners with a straight in intake bolt pattern (bolt holes are perpendicular to the head). The SC1 version of the head was said to be different from the earlier version of the high ports. The D3 is the newest NASCAR head and uses a canted intake valve. It has smaller ports but works very well and can easily exceed 400cfm. The D3 is the best Yates casting currently available.
Yates C3 Head Information
Threaded Mode