Cylinder Miss

[enio45]

How do you make a determination if there is a problem with the valves or the cylinder. I have a small miss at all RPM's and have replaced plug, wires, cap several times.

Seems like it can be a burnt valve or Cylinder problem. Cylinder compression runs 150 - vs others at 165.

Not sure what to do next to hone in the diagnostics....

Appreciate any advise.......

[Norm reynolds]

The next thing you could do is a cylinder leak test basically it’s a tool that you hook up air from your air compressor in to the gage you hook in the gage where the spark plug hole make shore the cylinder is at top death center the gage will give you the amount of leakage What you are looking for is with the carb at wide open if you have a burned intake valve you will hear air coming from the carb If you have a burned exhaust valve you will hear air coming out the tail pipe and if it’s the rings you will hear air comeing out the dip stick

[Salvatore]

Look closely at your valve train....rocker arm, valve spring, pushrod. Have someone crank it over and make sure the valve is opening and closing, while you watch the rocker arm move. Do you have a valve tap? http://www.yenko.net/ubbthreads/images/graemlins/headbang.gif

[enio45]

Thanks for the advise guys......

I have no valve tap - it does have solids on the cam . I have good lift on the valve train - i did a compression test a while back and saw the compression gauge show some leakage after i first turned it over to get a reading. I then cycled it again and this time it hold for quite a while then leaked down slowly. I will need to do the sound check as recommeded to hear where the leak is - cyl, carb or exhaust??

Assume no other way to do this?? http://www.yenko.net/ubbthreads/images/graemlins/confused.gif

[Charley Lillard]

Get a set of pliers for pulling plug wires and pull one wire at a time from the dist cap while it is running. You should be able to narrow down the problem cylinder by listening. If it gets worse it is probably not the cylinder that you just pulled the wire from.

[moparts]

Shoot a little oil in the cyl. on your compression test.....if compression raises the oil helped seal the rings if it doesn't raise it's the valves.

[Belair62]

Good advice Moparts...oldest trick in the books....I've used Charleys to pinpoint a cylinder too.

[Salvatore]

If you have solid lifters. try re-adjusting them. Maybe you have one too tight. Possibly a bad valve. Does it miss when you rev it up? Might be a lean condition or vacuum leak. http://www.yenko.net/ubbthreads/images/graemlins/dunno.gif

[enio45]

OK thanks for the advise and good tricks of trade...ill schedule time next weekend to diagnose this and get back to everyone.....thank you again