Vibration under acceleration, troubleshooting

[pofo]

Hi guys, pardon my english, I am from Norway.


I did a compression check today.

The engine (as far as I know):
Stock 350 with the original Rochester Quadrajet carb, no modifications.

The truck:
1976 C20 Silverado with a TH350.

It was stored outside in the norwegian winter, it was around -17C at the coldest. A buddy of mine started it up and let it idle till it got warm 3-4 times during the winter.

In springtime I drove it 260 miles without problems. After that I drove it around town for a couple of days and noticed a vibration while accelerating. It has some uneveness/shaking while in P and some throttle, maybe 1200-1600 rpm.

I got the following results:

Sylinder 1: 137psi
Sylinder 2: 150 psi
Sylinder 3: 137 psi
Sylinder 4: 150 psi
Sylinder 5: 135 psi
Sylinder 6: 140 psi
Sylinder 7: 138 psi
Sylinder 8: 150 psi

The lowest was 135 psi and the highest was 150 psi.

Are the compression OK? Whats the next thing for me to check out/do? I changed the fuel filter without effect.


Thanks for tips and answers!