Yep, I guess the carb is contributing to the instant black on a new set of 3 plugs. Were it a bad set of rings in one hole, one plug would be black not all three. They call it super sleuthing..... nyuck nyuck

ok round two compression readings are:

1 105

2 100

3 100

4 100

5 105

6 100

I stood at the throttle linkages while warming her up and revved up to maybe 4500 or so.... some blackish smoke comes out

Edited August 27, 201014 yr by bounce

here's the plugs: plug #4 is whiter on the other side.......

Looks like the front carb is running rich, It could be the idle setting or the jets.

One other thing, I was able to find a service manual for my 77 Z on the web. It will have all of the specs and should help you troubleshoot also. So look for one for yours.

Edited August 27, 201014 yr by bergermiester

carbs will be fixed soon. as in like new from Ztherapy.

Cool I just brought mine back to life two weekends ago. It needs a lot of work but it will be cool when I am done. The body is solid and the price was right.

ok round two compression readings are:

1 105

2 100

3 100

4 100

5 105

6 100

I stood at the throttle linkages while warming her up and revved up to maybe 4500 or so.... some blackish smoke comes out

The numbers seem low, but they are very even across the board, which is good. The lowness could be as simple as a low-reading gauge.

The numbers seem low, but they are very even across the board, which is good. The lowness could be as simple as a low-reading gauge.

that's good news....

there is a nice crack in the glass lense of the comp tester gauge....

Looks like the front carb is running rich, It could be the idle setting or the jets.

Or the front choke stuck in the down position.

The lowness could be as simple as a low-reading gauge.

I agree that the gauge could be suspect. Your readings on #1 and #6 were higher the first time you did it when the engine was cold and the throttle was closed. This does not make sense, I'm guessing your numbers are actually higher than you are measuring.

there is a nice crack in the glass lense of the comp tester gauge....

There's your problem.