Almost forgot to mention that AMC used the ridged rocker assemblies on the later model heads that had pressed rocker studs and larger pushrod guide holes. The bridged rockers held the rocker arms in place, keeping the pushrods properly aligned. If you have the pressed in rocker studs in your heads you will need the bridged rocker assemblies if you do not have a machine shop replace the rocker studs. When I have an engine built for extra performance over stock, I always have the pressed rocker arm studs replaced with the screw in type. The pressed rocker studs can sometimes come loose with heavy duty valve springs from a performance cam and valve train setup running high revs so I always have them replaced on any heads that I use on a built up motor. When you have the screw in type studs, the guide plates can be put in at the same time as the studs are replaced. Regards, Dan Curtis d.curtis@xxxxxxx 602-317-2018 >Shrews, > The larger diameter pushrod hole you are experiencing is a common AMC > condition that is easily resolved with AMC or after market pushrod guide > plates. I had a set of 74 401 heads on a 69 AMX 390 with roller rockers > and it had the guideplates installed under the rocker arm studs. _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list