Tailpipe paper test?????

[Danny Gutierrez]

  I was reading the tech section of the January issue of Hot Rod, and they suggested a "paper" test to check for burnt exhaust valves.  It said if you place a sheet of paper against the tailpipes at idle and the paper gets sucked back against the pipe then you have one or more burnt valves.  Is this true?  I tried the test on my 69 and the paper gets sucked back on both exhaust pipes.  My engine blows blue smoke and I was considering a rebuild.  Perhaps a valve job or new heads my be good enough.  Any suggestions?

[firefighter3931]

    Any suggestions?

Yep, run a leakdown test on your engine, cylinder by cylinder. Basicly, you back off the rocker shafts to close all the valves and seal up the cylinders. Once that's done you apply air pressure through the sparkplug hole with a threaded hose and listen. If air is leaking out it will be going one of two places....either the crankcase or exhaust/intake manifolds (depending on which valve is bad). Blue smoke would indicate a bad exhaust valve....assuming the valve was bad and not the rings. A guage helps in that it allows you to see how much PSI is leaking and how fast it's leaking.

You'll be able to hear it either out of the tailpipe or into the engine crankcase....or out the carb if an intake valve is leaking (allthough this isn't the cause of your blue smoke).

Ron

[Khyron]

now that there is a serious answer i'll post my comment...




so you're saying your car sucks?


*rimshot*