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Broken Guide Plates
Well, 351C was running a bit poorly, so I thought I would adjust valves this evening. After I removed valve covers, I noticed 3 pushrod guide plates were broken. After further inspection, I saw these 3 pushrods were bottoming out in the guide plate slots at full lift. Obviously I didn't check everything well enough when I built this engine. Should have been more careful with these 3/8" dia. pushrods. Luckily, no pushrods were bent, so I bought another set of guide plates at local machine shop (Which speaks Ford very well). I relieved new guide plates with end grinder and burr, installed them and set valve clearance. Now runs much better and even hits much harder. Just wondered if anyone ever ran into this problem before. Later, David Shelton.
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Dave: Yes this is more common than you might think. Depending on the rocker arm ratio and cam lift being used it is often possible for this to happen. The engine builder should cycle the engine (rotate two revolutions) and checks each rocker. Checking for pushrod interference and also for the rocker arm and spring retainer contact.
On the Windsor Jr heads I use I found it necessary to use guide plates made by ISKY that are intended to be welded after the correct spacing of the pushrods is determined. The OEM/Manley pieces did not put the rocker roller tips directly over the valve stems during setup. I found this strange as there was nothing in print refering to anything unusual that would be required. Just a thought...........Rick |
The same thing can happen on the rocker arms themselves on non-shaft mounted rockers. That's why you'll hear about "long slot rockers"
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I remember checking for correct pushrod length with an adjustable pushrod, checking for correct alignment side-to-side on guide plates, alignment of Crower S/S rockers with valve stem tips, looking for contact of underside of rocker arm with retainers, and checking for coil-bind and piston to valve clearance, but I for some reason, never thought to check for depth of guide plates, but I never will forget after now. Later, David Shelton.
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