240z not starting, low compression in 2 cylinders

[airbornealex]

I am new to Datsun, I always wanted a Z and stumbled into a 1972 240z about a week ago. The car ran when I bought it, run being a overstatement. Now it will not start, it sputters, nothing more. I have gone through the round tops and adjusted the floats, that seemed to help it run and start a little better when it still ran. I set the timing to 5 below like the haynes said, that helped it start better when it did, and finally I put a little marvel oil down the cylinders to even out some compression numbers that I had. these are cold numbers at 6000 above sea level;

1.) 120

2.)120

3.)95

4.)100

5.)120

6.)105

After sitting for a day my new numbers are;

1.)125

2.)120

3.)45

4.)60

5.)120

6.)95

Now the car will not start like I said, just sputters. When the car ran before it hesitated during throttle application and idled like it had a large cam. Any advice?? Please help.

[beermanpete]

The comprssion is not great but is not likely the reason it won't start. Check to make sure you have spark. Maybe the points need to be cleaned and adjusted.

[zbane]

the compression levels look to me like a classic example of head gasket failure... I know from experience; your description of how the car ran before failure also sounds familiar.

[Zed Head]

Are you using a screw-in gauge or one of those ones with the rubber plug you hold in the spark plug hole? It's odd that you would lose 50 and 40 psi on 3 and 4 just from sitting for a day. The measurement results doesn't look right. They should be consistent, if you're not starting the engine between measurements. You said the first was cold, so I assume that you measured cold, waited a day and measured cold again. No reason for the head gasket to blow, just sitting.