anyone with a 2.3 capri! Prop Incompetence-gctid391586

[Guest]

Im thoroughly confused about what prop pitch I should be running on this boat. 89 19 capri with a 2.3l cobra I/O. If someone needs the gear ration I can get it.. hoping someone with the same boat will just let me know what they are getting for WOT and what pitch they are running. I have read more than a couple posts about the same model same I/O setup running 17P's and being able to go over WOT of 5600. I can barely get 5100 running a 13 ┬╝ 15PÔǪ that's what came on it when I bought it. Be great to compare to someone with the same boat so I can start looking elsewhere as to why Im not reaching WOT. I have a tower on the boat and use it primarily for wakeboarding, so im looking for a strong hole shot. From what i gather, a 15P should give me the best hole shot and be able to blow my WOT... im so confused. Thanks for any input.

[Chief_Alen]

Engine Won't Reach Operating RPM. Check

1. Fuel condition. Type and Octane possibly old fuel

2. Propeller pitch or diameter, damaged blades

3. Restricted fuel pickup tube or anti siphon valve Fuel System Test

4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse

5. Marine growth on hull and outdrive

6. Wrong gear ratio in outdrive

7. Restricted carburetor air intake (clogged flame arrestor)

8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive

9. Poor cylinder compression Compression Test

10. Carburetor defective, or wrong type.

11. Fuel pump pressure and vacuum

12. Boat overloaded, improperly loaded, or improperly trimmed.

13. Engine Overheating

14. Engine timing and ignition system operation

15. Remote control cables and linkage for proper travel to open throttle plates fully.

Above copied nd pasted from another website Don s is the author.

[Guest]

Here is the information directly from the source:

1989 Cobra 2.3 Parts catalog lists the following props:

Aluminum

14X11

14X13

13 3/4X 15

13 1/4X 17

13X19

12 3/4X21

From the OMC 1989 Service Manual:

boat speed diameter pitch

17-20 ft runabout 30-40 13 1/4 17

16-19 ft runabout 32-42 13 19

the above is for aluminum prop

I don't have the gearbox ratio.

As for my boat, I can run at 28mph (gps ground speed) at about 4200-4400 rpm.

[Guest]

Timing and fuel

10 degrees BTDC w/86 octane or higher set at idle (600-650rpm) WOT is 5200-5600 rpm.

From experience, if timing is off, top end and acceleration are poor.

Gear ratios

upper gear ratio is 21:21

lower gear ratio is 13:26

total ratio is one rev of the U-joint input shaft is 0.50 rev of the propeller shaft (output shaft)

or

2 revs of the U-joint shaft equals 1 rev of the propeller shaft