351c ?
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Junior User
Joined: Mar 2004
Posts: 80
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From: Texas
351c ?
I am asking this for a friend, he has a 351c 4v heads, he changed the stamped steel rockers to roller rockers and the engine went to dropping valves. Replaced retainers, keepers, springs twice, has screw in studs, guide plates. When it drops a vavle it either pulled through the keepers or broken the retainers. All parts are name brand and matched to his camshaft. Any help would be appreciated. Thinking about buying this engine from him if we can figure this problem out. Thanks Billy!!! note this engine is in a drag car that has run 1/4 mile 10.10 @ 128
Senior User
Joined: Dec 2004
Posts: 236
Likes: 0
From: Southwest Montana
dbhr,
Broken retainers? sounds like something is going solid. Factory match just means that sombody somewhere decided to put all those parts in the same box. I would turn that over very carefully and at max lift see how much more the valve can move before the spring locks together. If need be you can mill out the spring boss to gain some more travel. how much seat pressure does it have?
incedently at what RPM is this thing coming apart?
MY $0.02
Ken
Broken retainers? sounds like something is going solid. Factory match just means that sombody somewhere decided to put all those parts in the same box. I would turn that over very carefully and at max lift see how much more the valve can move before the spring locks together. If need be you can mill out the spring boss to gain some more travel. how much seat pressure does it have?
incedently at what RPM is this thing coming apart?
MY $0.02
Ken
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
Generally a spring "going solid" results in bent pushrods and/or a wiped camshaft. I'd bet the valvetrain geometry is off. If it's happening at high RPMs it may be there's enough deflection of the rocker studs and the rocker tips are making contact in the wrong place resulting in the broken hardware.
