Alright I'm at my wits end here, I recent got my old 1975 Ford F-100 back, well the 289 that was in it I had put in years ago and it developed a rod knock and it was sold. Well recently I bought it back and bought a 1984 302 out of a mustang, did basically a cheap go through of the engine, re gasketed it, new Comp magnum double roller timing set put in straight up, Small summit cam (.512 lift 112 LSA 228 @.50), New Comp Cam springs, factory aluminum 4 barrel intake off of the mustang, and a Holley double pumper.

I took the heads off the 289 which were D20E heads off a 302 for the smaller chamber and adjustable valve train. Did a little work to them, bowl blend, and milled .020 thou. Well I go to break in the cam and after about 10 minutes into the break in I hear a rocker tapping, shut it down and pull the valve cover, had some loose rockers and one came off of the valve completely. Well I go through and fix everything and start it up again to finish the break in, does just fine and right when I go to turn the idle down to shut it off I hear it again, it's the same couple rockers giving me the problem. At first I thought it was possibly the stud pulling up but I've checked it and they are all the same, go through and re lash the valves and the rockers are still al little loose almost like it's got to short of a push rod and a couple nuts keep coming loose. It's a weird factory set up on the rocker nuts, it's your normal 9/16 nut to adjust the rocker then a 1/2 to lock it down kinda like a homemade poly lock. So what's your guys thoughts and a ideas on this?

 

Sounds like your locks are backing off you may want to change to a poly lock nut

 

I 2nd it on the poly lock , not going to hurt and not costly .

 

I can get a set of polylocks from work, do you think they would work on a stock style rocker arm? I've never tried them on stock rockers.