The motor in my sons car is making some vale train noise. I'm trying to narrow it down.

stock 1990 short block
GT40 heads

The guy I bought this car from absolutely had no idea what he had. Everything he's told me so far has turned out to be wrong. But not necessarily in a bad way.

He said it had a B-303 or E-303 he wasnt sure with 1.6 roller rockers.

Well I took off the valve covers this morning to see if the rockers or push rods were the source of the noise. No such luck. But what I did find was that the car has 1.72 SVO roller rockers in it. Nice rockers but with an E-303 wont this cause PTV issues on a stock 1990 shortblock? What abot with a B-303 cam? whats the limit guys? Do the 1.72 SVO rocker require specific pushrods? If they put stock pushrods in there could that be the source? Bent pushrods? Could the motor be quiet at start up until the lifters pump up and then because of the 1.72 rockers create PTV problems?

I fired this thing up this morning as it was perfectly quiet. Smooth idle, sounded good. But as soon as it warmed up there is a knocking or rattling noise. Not like a rod bearing,.. but possibly the thrust (plate or bearing?) for the cam. It sounds as if the cam is walking all over the place in there. Could a bad timing chain cause this also?

Either way I need to open up this motor to find the source of the noise,.. but open to idea's and what I should look for.

I was thinking the push rod might be bent or possibly the it has a collapsed lifter or two because of the cam and rockers. Anyone run this combo before. What should I look for?

Thanks guys.

Hurst