Over the Holiday I was talking with my father inlaw about my 1971 Imapla 400 Small Block and how it was running like crap and smokes alot. He's been around cars and had a few projects so I was picking his brain for some knowledge. Several things came up that I wanted to run buy you gentleman on this fine forum.

Putting Tranny Fluid in the gas tank to blow the carbon deposits out of the motor? Has anyone else done this? He said it was a old trick people would do on cars with lots of miles on them for a kind of tune up.

He then cut out some cardboard and placed it against the end of the tail pipe and it fluttered or smacked back and forth. He said it shouldnt do this and said possibly had cylinders that were not firing or also a stuck valve? We pulled each wire off the distributor to check which cylinders were not firing and as it turned out when undoing the number 1 cylinder it had no effect on the idle of the motor.

As it was running I showed hime the smoke coming from the exhaust so he said to pull the radiator cap and see if it was gurgaling or bubbling and that would be a sign that air was entering the radiator through some kind of leak, either Head Gasket, Warped Head etc. Well the radiator was only have full after I had filled it up several months ago after I had brought it home. I have only driven it around the block or moved it across the street when mowing to get it out of the way. Is there a better way to tell if this is just a blown Head Gasket or something more serious like a warped Head other than tearing it down?

What's your opion? What would you do? Let me know if more info would help

Thanks,