Loss of Power at Higher RPMs.

[Greg Kingman]

Good Morning to My fellow A-4 Owners-
Last winter I pulled my A-4, found a Blown head gasket.
Replaced & bench tested and found that the motor seemed to run better with looser valve settings than those prescribed by the manufacturer. I installed fresh water cooling and am finding that the motor runs at 170-180 range vs. the 145-160 range with seawater cooling.
The motor has good power in the lower RPM range, but as I approach 1000 rpms it doesnt respond with more power, but does drive the temp up.
Any thoughts on this subject would be greatly appreciated.
Greg

[Kurt]

Have you looked into your exhaust system in detail. Elevated exhaust backpressure can cause this problem.

[Dave Neptune]

Power loss

Greg, since you had the engine out have you reset the timing by power timing it? Lazy timing can cause a similar condition.
I would first try the timing in the slip then I would consider the exhaust. How old is the exhaust?

How much is the temp rising? At 1000 rpm your not really developing much power and shouldn't really see a temp rise unless your working her considerably harder.

Dave Neptune

[roadnsky]

The motor has good power in the lower RPM range, but as I approach 1000 rpms it doesnt respond with more power, but does drive the temp up.
Any thoughts on this subject would be greatly appreciated.

Greg-
Try "pulling" one of the spark plug wires and see if she runs better.
IF she does, then disconnect the exhaust at the flange, and try running her at the dock (higher RPM under load)
It'll be loud and don't breath deep!
If the symptoms go away, you have exhaust back pressure (blockage).

Try it and let us know...