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FE Technical Forum / Re: S Code 390 - practical power increase if keeping stock heads / exhaust
« on: January 16, 2026, 09:12:47 PM »If your engine is truly a 57K mileage and never been into, then you should definitely think about changing the camshaft timing gears and chain. You can still find C6AE-9425-H aluminum intakes and C7AE-F intakes with the thermactor tubing holes and remove about 50# from the engine. 735 cfm Holley and FPA headers, and 2 1/2" exhausts and call it good for the street. Joe-JDCI absolutely agree with Joe on replacing the stock nylon camshaft timing gear, if it is still in there. Same with the valve stem oil seals. I have pulled down quite a few "untouched" Ford engines, that had an abundance of fragmented nylon timing gear teeth, and disintegrated valve stem seals in the bottom of the oil pan. And for whatever reason, Ford chose to put a round hole in the screen of the oil pump pickup tube, which is more than adequate to allow small pieces of cam teeth/valve stem seals to find there way into the oil pump, which will jam up the oil pump gears, which then lock up, and twist up the oil pump drive rod, like a barber pole, until it snaps. The engine keeps running, but with no oil pressure, and even if you catch it as soon as the oil pressure gauge drops, or the idiot light comes on, and the lifters start ticking, there is a very good chance that you won`t be able to shut the engine off before the crankshaft bearings get destroyed.. I lost a very good running , low mile 302 in my 79 Mercury Zephyr Z7 that I bought from the 94 year old original owner about 10 years ago. I was cruising down the freeway, and suddenly the oil light came on, so I shut off the engine right away, and coasted to the side of the highway. I checked the oil level first, which was fine, but when I tried to crank the engine over, it was already stuck. I sure wish that I would have changed the timing chain set and valve seals before hand.
