67 johnson 60hp compression reading....is it ok?

[zaner]

I did a compression test on all 4 cylinders and 3 read 95 psi and 1 reads 110 is this ok. Motor runs smooth at mid to high rpm's and idles rough at low rpm and smokes alot just at lower idle. It also seems to run better under load sounds smooth and no chop.....carb problem? new plugs, coil, condensor,and cleaned and rebuilt carb and clean all cap rotor and wire connections. thanks for all help and suggestions.

 

[OBJ]

Re: 67 johnson 60hp compression reading....is it ok?

Your a little on the low end of the 10 > 15% scale. Did you take the compression readings with the engine cold? If you warm it up, the readings may come closer. <br /><br />The rough idle is likely from the carb needles needing some adjustment. Sounds like one is running rich. Adjust your low speed needles with the boat in the water in gear and underway. Makes a difference.

 

[zaner]

Re: 67 johnson 60hp compression reading....is it ok?

thanks you advise sounds good I will give that a try

 

[dc in ms]

Re: 67 johnson 60hp compression reading....is it ok?

A maual I was reading the other day said the readings should be less than 15% from each other. It said that if there is greater than 15% difference in any of the cylinders then it needs to be evaluated by a tech. If it runs fine now I would just leave it alone. But, that's me.

 

[Paul Moir]

Re: 67 johnson 60hp compression reading....is it ok?

If one's running rich or misfiring it'll often read higher since the cylinder is wet. Try taking the compression on the high one a couple times and see if it drops off as the fuel/oil clears.

 

[tashasdaddy]

Re: 67 johnson 60hp compression reading....is it ok?

search for Joe Reeves post " setting low speed idle" very detailed.