boat seems gutless

[cptnridindirty]

1978 merc outdrive,
chevy 350 ,
19 p prop ,
19 foot celebrity

engine will rev to 6500 in nuetral,put it in gear and the best you can get it 3600 and it moves ok across the lake but not what i would expect from it,seems as though it has a hessitaion /stumble when you go wide open ,my friend has a 4cyl and i could not keep up with him on the water ,the previous 2 owners had told me this bout would do aprox 45 on the water ,this is the first inboard i have owned ,am i just expecting to much from this boat ?

 

[Don S]

Re: boat seems gutless

engine will rev to 6500 in nuetral,

Usless test, it will do 9000 rpm in neutral with half the plug wires pulled off one side.

the best you can get it 3600

List of possible causes of low WOT (Wide Open Throttle) rpm.

In no particular order

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.

 

[NHGuy]

Re: boat seems gutless

I used to ride dirty, now I am a daddy.

 

[jtmarten]

Re: boat seems gutless

I'd look at #7 and #14 that Don posted. A 19p prop should get you to 44-4600 easily.
Make sure you have plenty of fuel flow, new filter, etc.
Make sure your dizzy is getting full advance, all in by 3000rpm.
Years ago I put a new HEI on my jetboats's 454. Not even thinking about the advance I took it to the lake, and it was a serious slug. I had the dizzy setup by a machine shop to be fully advanced by 21-2200rpm and she was a beast after that.
You should have 34-36* total advance. If the dizzy provides 22*, your initial timing at idle would be set at 12-14*.

 

[180shabah]

Re: boat seems gutless

engine will rev to 6500 in nuetral

Not for long