Ford 302 Engine
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Ford 302 Engine
I have a question on a Ford 302 Engine. I have a 1969 302 in a 1976 F250 2 wheel drive. The cylinder heads were leaking on a couple exhaust valves so I aquired a set of 1970 heads which are suppsed to be the same and had them made ready to go with new valves, seats and guides. There is a difference between the 69 and 70 heads. The 69 heads have the adjustable rocker arms and the 70 heads have the non adjustable rocker arms that from my experience you just tighten them down and call it good. I was concerned about them but when I tightened them down they seemed to compress the lifters so I thought it good. The rocker arms are "clacking". What, if anything, can I do to remedy it? Do I need longer push rods? Is there somehting I did wrong? I put new lifters in it and maybe I just need to let them get pumped up. Any Ideas would be greatly aprreciated. -Larry
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I am pretty sure that there is no difference in the rocker arms, (or much of anything else, for that matter) between 69 and 70 heads. I could be wrong, because I'm not 100% sure about that, but I strongly suspect you have much later model heads. Do the rocker arms attach with bolts or studs? I don't suppose you got the casting #'s of those ,by any chance? Being later model heads would explain the need for longer pushrods, as they came with them.
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From: Southern Oregon USA
289 engines built after mid-1966 and 302 engines use a rail-type rocker arm. These rocker arms have ears that extend downward, forming a rail or channel over the valve stem. This rail maintains proper alignment. The pushrod passes through a loose tolerance hole in the cylinder head, resulting in a cheaper assembly.
At high RPM, however, these rockers can jump the track, loosing alignment with the valve stem and resulting in potentially serious engine damage. These engines do not require hardened pushrods. This scheme was fully adjustable until 1970 when the studs were changed to incorporate a positive stop. The rocker arm nut is no longer used to adjust the valve clearance. Rather it is simply tightened down. Longer or shorter pushrods are selected to adjust the clearance. Since these are non-adjustable they can not be used with mechanical cams.
Jason
At high RPM, however, these rockers can jump the track, loosing alignment with the valve stem and resulting in potentially serious engine damage. These engines do not require hardened pushrods. This scheme was fully adjustable until 1970 when the studs were changed to incorporate a positive stop. The rocker arm nut is no longer used to adjust the valve clearance. Rather it is simply tightened down. Longer or shorter pushrods are selected to adjust the clearance. Since these are non-adjustable they can not be used with mechanical cams.
Jason
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From: Central NYS
Originally Posted by RCrawler
289 engines built after mid-1966 and 302 engines use a rail-type rocker arm. These rocker arms have ears that extend downward, forming a rail or channel over the valve stem. This rail maintains proper alignment.
