Volvo penta aq231a petrol wont rev?

Question

I have been pulling whats left of my hair out tring to find why my v8 engine wont rev.

Things that have been done,

complete fuel system overhaul including new pumps and filters,new points, condenser, coil,ballast resister, carb switched from other engine which revs ok compresion all good at 165-175.

Engine revs fine out of gear and sounds strong.

Props are all good and because it has twin engines i can rule out wrong size props.

any help would be appretiated.

Answer 1

When was last time you changed plug wires

Another area to look at is the drive check condition of oil and check magnets on drain plug for what appears to be shiny brass particles. The outdrive uses what they call a cone clutch setup . If your oil qaulity is weak or if you find it milky this will cause slipping of the cone clutch.

If you find it milky have it vacuum and pressure tested for bad seal, These outdrives are notorious for the seal behind the shifter which is behind the back cover of the drive

Answer 2

can you say "valves".  have you set the lash?  easy to do and will make a bear act like a lamb.

Answer 3

Does the other motor rev OK in gear?

If so, then there doesn't seem anything wrong with the engine. You say it revs OK out of gear, so it must be the outdrive or the prop.

Are you sure there isn't anything wrapped around the prop?

If not then the outdrive is shot.

Hope this helps Bigpathome.