Beob

Finally got my 455 running, after breaking in cam drove for a few miles. When I got back to my house I heard a lot of chatter coming from the rocker arms. I have roller rockers with hydraulic cam and used breakin in oil with zinc. Is this normal and what is the best way to adjust rockers?
Thanks, Rob

cutlassefi

What cam do you have?

Beob

Cam is a jm-25-28. Also, after driving around a while then let engine idle oil is around 20psi and a bit jumpy.
Thanks, Rob

67Olds442X2

I adjusted my rockers per instructions whether best or not is up in the air. Doing one cylinder at a time I rotated the engine in the normal clockwise direction until the exhaust valve began to open. I adjusted the intake valve to zero lash, spinning pushrod with fingers until you feel resistance. Then I tighten 1/2 more turn. I then rotated the engine until the intake valve was fully open and just starting to close. I adjusted the exhaust valve to zero lash then 1/2 more turn. This was Lunati's procedure since I used their cam and lifters.

I had some rocker chatter also but that was some of my poly-locks that had come loose. I assume your chatter might be miss-adjustment maybe. Pushrod length comes into play also.

Beob

Thanks very much, this info will help alot. Rob

67Olds442X2

Also, not sure what parts you are using but I found out the hard way that the Comp Cams High energy die cast aluminum rocker arms and the Comp cams hi-tech 3/8" push rods don't work together without first modifying the rocker arms. Best not to use them together. 5/16" push rods would probably work fine or better rockers. Good luck.

Dan

SBORule

Sounds like you don't have them adjusted right, too loose, not enough preload.

Beob

Still need some more advice. I tightened up a few of the loose rockers and added stp oil treatment to raise viscosity. It did help stabilize and raise oil pressure a bit, but after driving a few miles one of the same rockers started to tap again. Could there be a more serious problem? Should I tighten it again? Spoke to the builder once and was advised to not tighten rockers anymore but I cant seem to get in touch with him lately. Any advice appreciated.
Thanks, Rob

cutlassefi

You may have other issues but for fwiw those cams tend to be a bit noisy. Some people have higher tolerances for noise than others.

442_Mustang

If the same rockers are getting loose, it could be eating the cam. I'd pull the oil filter and cut it open.

Beob

If you say these cams tend to be noisyI will live with it. Just curious why, from my exp solid lifters are noisy and hyd are quiet. Thanks

Rickman48

X2 on cutting open the filter, if it's the same valves coming loose!