Mercruiser 260 prevortec

[prockvoan]

Re: Mercruiser 260 prevortec

No,it is not running that bad at a higher rpm.I had learn one thing,if the disturbitor is not set just right,it will not time right.It had to be on the right gear,very senative and no room to play.One other thing,this is a RH rotation motor.

 

[prockvoan]

Re: Mercruiser 260 prevortec

Ran a compression check.All cyls are at or around 147 to 150,but #7 is 139.Did a wet check,pressure came up to 149psi.When I had pulled the spark plugs,alot of carbon build up,# 7 very wet with gas.Pulled #7 plug again,swap out wires and plug,grounded it out,good spark.Ran it again,pulled the plug again,plug is still wet again.Thinking that the intake valve is not closing all the way.Any ideas?

 

[Don S]

Re: Mercruiser 260 prevortec

What kind of spark plugs are you using. If you have champions, you have a problem. Put a set of NGK, or Bosch Platnums or even the AC plug and it will probably work fine.<br />If a valve was sticking or not sealing, the compression would be way down. A cylinder that is getting too much fuel will also show lower compression because the oil is washed away from the rings, and with only 11 psi difference, you don't have a valve or ring problem.

 

[prockvoan]

Re: Mercruiser 260 prevortec

Using NGK plugs.