i went to change my head gaskets on my 74 comet with a 69 302 in it. put everything back together and it won't run right now. it sounded the the timing was off. so we went through different codes. then we think we found the problems, two rockers keep slipping off. we doudle bolted it and lock it down and it still slips off. my friend thinks because i did not torque the rocker arms down, it might have messed it up. other thing i got a burnt valve and need valve work. want i do not get is that i drove it up to his house fine and now it will not drive at all. 1. its backfiring through the carb. 2. will not stay running unless i hold the gas 3. rocker arms keep slipping off help me very frustrated misfitruss :confused:
Is the engine stock? Are you using rail type rockers? they are the ones with two little "guides" on the tip that keep it centered on the valve stem? If not, you'll have to use push rod guide plates to keep the rockers from sliding off the valve
When you say "the rocker keeps slipping off" do you mean that the rocker falls over off the valve tip or the pre-load comes off like the nut is loosening up? If it keeps falling off the side of the valve tip - what Russ said. If you just keep losing pre-load here are a couple of things it could be; 1) nut backing off losing pre-load You might just have to get new nuts - if memory serves me correct the nut on the early rockers is a deformed metal type locknut that the end is kind of mushed in. They are really only good for one or two times and then they will not lock) 2) Rocker arm stud pulling out of the head (did you by chance swap to a set of tighter springs)? 3) Lifter and or cam lobe going flat. (hope not) Valves losing adjustment will makebackfire but not running unless you hold the gas" and backfiring through the carb could also be ignition timing or a big vacuum leak. Is the intake tightened down good? When you had the heads off did you have the heads milled? If the heads have been milled a couple of times the intake might need to be milled to match the heads. Burnt valve? Replace it. Sure to run bad with one of those. Sorry for more questions than answers. Valve train stuff can drive you nuts. Keep you head up! Cleaver
One problem I ran into while building my engine. I got the heads at a swap meet. they are 66 289 heads. Somewhere before I got them, someone milled them for push rod guide plates, and screw in studs. They milled off.200" from the rocker arm stud stantions, and taped them for the studs. Well these 66 289 heads have valve guides cast into the head. so these heads didn't need to be milled .200" for the guide plates. To make a long story shorter, my screw in studs were too short, not allowing the rocker nut to ever get to the locking point. I ended up having to replace the screw-in studs with longer ones to make up metal the was milled off. Russ
