Still Low RPM at 5000 ft Elevation with High Altitude Jets

[Coloradolakeboy]

Since re jetting for High altitude, I am only getting 3000 RPM and bogging under load (Tubers). Full Throttle RPM range 5300-5800. Once planed out and motor trimmed occasionally 5000 RPM . Idle is fine. Carbs and Fuel Pump rebuilt and new lines and bulb, Ignition test out good. 15000 volts on plug wires. Link and sync done. Can you recommend a prop? Local Prop Shop guy does not think I need a smaller Prop and suggested check the Fuel Pickup in the tank (Not done yet).

Boat
1980 Glastron HPV 175 17.9 ft 1180lbs
90" Depth
35 3/4 Motor Shaft Length
20" Capacity
25 Gal Fuel Tank


Motor
1980 175 HP Mercury V-6 (With High Altitude Jets currently in Carbs)
2:1 Gear Ratio
378 lbs
Sea Level Prop used 21
Current Prop Merc 14.5 x 17
Full Throttle RPM range 5300-5800

 

[steelespike]

Re: Still Low RPM at 5000 ft Elevation with High Altitude Jets

Even with the jets your power will still be down about 15%.
Sure seems like a 17" prop would work.Have to wonder if jet install was messed up or the wrong jets.

 

[Coloradolakeboy]

Re: Still Low RPM at 5000 ft Elevation with High Altitude Jets

Thanks for your response. The Tach was acting goofy when I took the boat out this last Sunday. John Martin over on the Merc forum suggested testing the rectifer, stator and switchboxes. I had a tech test the ignition beforehand and he said it was fine.