Valve job? Or rebuild.

[Randra]

I have a 68 superbee 383 auto that I've had for 28 years
It was rebuilt in 1992. Car is just a driver. It may have about 60,000 miles on it. A couple years ago it started to backfire through the carb at cruise randomly. I've been pulling my hair out trying too figure it out. So I did a compression test.
Hear are the results. I see it has a blown head gasket between two cylinders. And why are the others so different from each other.

Dry Wet Wet Dry
------------ -----------
140 155 140 105


50 60 155 135


70 100 140 110


120 140 115 110
Front of engine

The engine doesn't burn oil. And runs fairly well. Do you think it needs a complete rebuild. Or do I have to just get the heads done.

 

[dieseldazzle]

I would think there is something wrong with any hole blowing below 120

 

[SublimeSixpack]

Valve job or rebuild?
I'd think rebuild.Those numbers don't look good! I'm no expert but when looking at your wet/dry readings I'd think you have some piston ring issues besides the possible blown head gasket on the right bank.
I'd apply compressed air to cylinder 4,6, and 7 one at a time with piston at TDC on compression stroke and listen to where you hear the most air escaping. Tailpipe, carb., or valve cover.

 

[mopar 3 B]

Valves or head gasket either way pull the heads. Piston rings should go well over 150000 with no problem if last rebuild was done right. Sound like a burnt valves and bad seats from running unleaded fuel. Pay close attention to exhaust valve seats maybe beat in to seat so bad valve train is not letting valves close all the way.

 

[1wild&crazyguy]

Valves or head gasket either way pull the heads. Piston rings should go well over 150000 with no problem if last rebuild was done right. Sound like a burnt valves and bad seats from running unleaded fuel. Pay close attention to exhaust valve seats maybe beat in to seat so bad valve train is not letting valves close all the way.

what he says.