Hello
I have a 66 FE block with stock heads. Under one of the bolt bosses for the rocker shaft, is a drain hole that goes to one of the head bolts - nowhere else. Should this be plugged? There is only one on each head. If anyone knows what this is for I would appreciate it.

Thanks
Charles

that's a oil feed hole, not return.
Oil is fed thru that, thru center stand to the rocker shafts were is then feeds the rockers themselves.
It's common on a rebuilt to use .090 restrictors to limit the amount of oil to the heads.
http://www.fordforums.com/f500/390-oil-restrictors-160176/
http://www.carcraft.com/techarticles/ccrp_0808_ford_390_fe/pictures.html

Here is the top side view of the oil feed into that bolt hole.


The put it on the intake side so it wouldn't cook the oil like it would if it were on the exhaust side. Here is a photo of the casting around the oil feed port, showing how it intrudes a bit into the intake


For the people who know these heads closely, they will note they are marine heads due to the brass plugs. A complete and very detailed photo documentation of these marine heads can be found at this link, on my personal web site. It exists for one reason, and that is to hopefully help someone, some day, somehow. If anyone sees any incorrect info posted there, please feel free to note them, as I want to be sharing good info.

http://www.network54.com/Forum/424840/message/1121461942

Regards,

Paul