Chevy rocker arms...

F-250 restorer · #1 (**permalink**) 11-06-2009, 09:47 PM

I've been reading about the chevy rocker arms on Ford 300's. Does anyone have knowledge of this--how much further they allow the valves to open? And what would that translate to if you had, say, a 260 duration cam? With the chevy rocker arms, would it be like having a 262, 264, 266 cam?

Also, for a 78 300, what year and model chevy would the rocker come from. I'm assuming it is a bolt on operartion?

Thanks for the help.

johnboy427 · #2 (**permalink**) 11-07-2009, 02:26 AM

No change on duration only a change in lift. Say you have .3125 lift at the lobe a stock 300 rocker is 1:1.6 so you have .500 valve lift a BBC rocker is 1:1.72 so you get .5375. I have never done this swap on a 300 before but that is basically how it works, it doesn't change when it opens just how much. There is a good chance you will need custom pushrods to get the geometry right. Studs and guide plates will be required.
-Johnboy

F-250 restorer · #3 (**permalink**) 11-11-2009, 12:42 AM

On another forum I was reading a great article about a racing 300, how to build one for more power.

He said that by using the rocker arms off a 230--260 Chevy I6 you get 10% more valve lift!!

dustybumpers · #4 (**permalink**) 11-11-2009, 07:17 PM

use the chevy 6 rocker arms. I have heard of people haveing the 10% more lift, but none mentons the 10% more wear on the tops of the valves, because of the wrong geometry.

F-250 restorer · #5 (**permalink**) 11-11-2009, 09:37 PM

It is not something I am planning on using. However, I do find it fascinating that it can be done.

Good point, Dusty, about the wear.

Hey, my build is fine for me...plenty of power when I need it, and decent mpg too. It's everything I wanted. AND THIS TIME THE OIL PRESSURE WILL NOT DETERIORATE!!

Harte3 · #6 (**permalink**) 11-13-2009, 12:50 AM

The Chebby rocker trick is a cheap upgrade to an engine with a stock cam. If one wants to factor in more lift with a bigger cam it is usually best to do it with a higher lift cam rather than adding the Chebby rockers to an already bigger cam...essentially what dusty said.