302 rocker issues
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Junior User
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From: mooresville
302 rocker issues
alright so i bent 2 push rods and broke a third in my 84 302 so i bought a replacement set of heads due to a bent valve and not wanting to rebuild the smog heads, the heads are off a 71 302 that was in a bronco, heres my issues i have new push rods and polished the lifters and set the valve lash fired up ran great till it started popping like a bunch of 4 year olds with cap guns.
every single nut that held the rockers down had backed off a good 3 turns per stud, any ideas what caused it to do this? push rod length is right its got the rockers from the 71 which are cast steel.
every single nut that held the rockers down had backed off a good 3 turns per stud, any ideas what caused it to do this? push rod length is right its got the rockers from the 71 which are cast steel.
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Junior User
Joined: Mar 2015
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From: mooresville
ive gone over and checked the lengths twice and i set the nuts down and set the valve lash and gave it the half turn more but they backed off, im not sure if i need to get new studs or just replace the nuts and hope the issue is fixed, the heads, rockers and intake are off a 71 block that are now on my 84 block
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From: Virginia
The 1971 should have Ford's "rail rocker" system on it. The rocker arm tip that touches the valve stem should be shaped like a "U" and have "rails" on each side to keep the rocker centered on top of the valve stem. These systems used positive stop rocker arm studs. They are not adjustable, you cannot set the valve lash with this Ford system like most other Ford systems. That's why the nuts came loose, they need to be tightened all the way down.
If you have a different cam, the heads have been re-worked improperly, or the wrong pushrods, then the whole thing is a mess and will not work correctly. Welcome to having a Ford engine. There is a way out though; The aftermarket used to sell adjustable valve train kits for the old rail rocker system. What they are is a very tall nut with a set screw in the middle. You can then adjust the valve lash with the nut like you did before, and then while holding the nut with a wrench, tighten the set screw down and it jams it tight when it hits the top of the rocker stud.
If you have a different cam, the heads have been re-worked improperly, or the wrong pushrods, then the whole thing is a mess and will not work correctly. Welcome to having a Ford engine. There is a way out though; The aftermarket used to sell adjustable valve train kits for the old rail rocker system. What they are is a very tall nut with a set screw in the middle. You can then adjust the valve lash with the nut like you did before, and then while holding the nut with a wrench, tighten the set screw down and it jams it tight when it hits the top of the rocker stud.
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Joined: Mar 2014
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From: AZ
OK, have ,you checked the torque on them when you get them to where you want them. The torque may just be to light to hold there position. This would require shims to get the torque needed. One other option is a little lock tight to see if it will hold them. I do not do this, but others have. If the shims do not work and add enough torque, then it is time for new shafts probably.
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From: Virginia
Comp cams has a different setup now, with locking nuts and spacers.
Comp Cams Rocker Arm Adjusting Nuts & Kits | Comp Cams
Comp Cams Rocker Arm Adjusting Nuts & Kits | Comp Cams
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