lack of power on 4.3 thunderbolt 5

[pae0332]

hey all, so i have this deck boat with a 2004 4.3 w/ 2 barrel mercarb and TB5 that was stalling out and found the carb needed to be rebuilt. i had that done and did a minor tune up, plugs and cap/rotor. when i tuned it i checked the timing and found it to be set @ 0 degrees, i reset it to 10 (using the jumper to the purple/black wire). she idled great after that work but when i took it out on the water now the boat wont get out of its own way. i cant get the rpms over 2800 under load. i had someone drive the boat while i adjusted the timing by ear but still wouldnt get over 2800 under full throttle. meanwhile prior to this work, the tach would climb up to about 4k. i tried trimming the drive, lightening the load, nothing seems to make a difference.
the boat is in a lake and has only been in the water for about a month so i dont think the issue is drag.
anyone have this type of issue?
there is no flame arrester cover and engine id # is unknown

 

[alldodge]

Check to see if the timing is advancing

 

[cyclops222]

Did you remove the jumper wire ?

 

[pae0332]

yes it is advancing and yes i removed the jumper wire

 

[alldodge]

yes it is advancing and yes i removed the jumper wire

Set at 10 BTDC and it is advancing (getting to and hope fully past 20* BTDC)
Start with the basics, compression test

 

[Fun Times]

What rotor part number did you put in?
Make sure there are 6 tabs vs 8.

 

[pae0332]

yes it is advancing past 20, and the rotor better be the right one, it came as a kit, cap& rotor but i will check, that would be a real kick in the ass. something you just take for granted. ill be back to follow up

 

[pae0332]

im thinking and there is no way the engine would run as smooth as it is if the rotor is a v8 rotor. if at all. but i will check it

also, whats troubling me is that before the tune/carb, it was operating better. the compression doesn't just drop