Ok, I have very limited info here but wondering if someone can give me place to start??? My father called me and told me his car has some serious issues and told me the following: Was driving down highway and started making a popping sound (possibly backfire but not sure), Oil pressure stayed good as well as temp. Got it home about 10 miles and popped the hood, at idle it would make a metal on metal noise maybe every 10 seconds and almost die, but other than that would idle fine. Has me stumped why the noise would be only ever 10 sec or so and when it does it then it comes close to dieing. Any ideas would be appreciated. The motor is a mid 70's 350 pretty much stock other than RV cam, edelbrock intake and carb, headers, high volume oil pump, double roller timing.

Broken Valve Spring?? Loose bolt on the flywheel/flexplate?

Can you go see the car? OR, is it too far away....

I'm gonna try and go tomorrow if weather permits. I was leaning toward valve spring to start with but just had me perplexed that noise was so intermittent and then it would try and die.

I would pull off the valve covers and inspect the valve train for starters.

May be something as simple as a belt driven accessory trying to lock up and you're hearing the bearing trying to sieze. May not be but I'd start with the simple stuff first.

Does the car have A/C?

Thanks for replies guys....No it doesnt have AC. Any more suggestions??? I'm gonna start with valve train and go from there, but would like to hear any other suggestions.