I am in desperate need of some advice, i have a 67 Chevelle Malibu with a 78 model 350 in it, my problem is that when i am driving along at normal speed and mash down on the gas
the valves in my car chatter really loud, i have timed it over and over,ran high test gas,added octane boost and nothing seems to help, this issue just came up i did not change anything on the car,
any help would be very much appreciated.

 

Few things come to mind. First, what is the valve lash/clearance from the rocker arm to valve(s)? Are these hydraulic or solid lifters? Gasoline isn't going to do anything for what you've described. When did this start, as in a new overhaul, or?

 

It has hydraulic lifters and the only thing i did to the car was pull the transmission out to replace front seal and when i got it out that spring it started doing this

 

The way I did it in the "olden days" was with a cut out rocker arm cover with the engine running, take he valve lash out. What I would recommend is set the rocker arm on each valve with the valve closed at about .010 inch with a feeler gauge, go from there.

 

Gonna give it a shot, really appreciate the help