Carb settings going from aq205 to 4.3 vortex

[loco]

Hi all,
Just got the boat up and running after having busted a pulley. The engine idled absolutely fine, and at full power was OK, but if you 'floored' the throttle it would bog horribly, to the point of almost stalling. Reading around, it's clear I need a carb rebuild, which is absolutely fine, considering its age.

Then I got to thinking - I replaced an old volvo AQ205a with this engine, but took all the ancillaries across from the old engine, including the carb. The new engine has vortex heads which I believe is around 220HP with the four barrel carb that I have.

So, my question is, should I have jetted the carb differently and had fractionally bigger jets? Any other settings to maximize performance for this engine?

The carb I think is a 4 barrel, double pump. It has model 8105B on the side, so I believe it's a 650CFM, likely the 4175 model (happy to be corrected).

Any guidance very much appreciated!

 

[loco]

No Title

 

[Bondo]

So, my question is, should I have jetted the carb differently and had fractionally bigger jets?

Ayuh,.... Probably not,..... But,....
The only way to know for Sure, is to do spark plug color tests at various loads, 'n rpms,....

The carb is still feedin' a 4.3l motor,....

Btw,...... What killed the old motor,..??

 

[Scott Danforth]

If your motor backfired, you probably took out the power valve which would give you the symptoms you are seeing

Doubt you would need to change jets

 

[loco]

Ayuh,.... Probably not,..... But,....
The only way to know for Sure, is to do spark plug color tests at various loads, 'n rpms,....

The carb is still feedin' a 4.3l motor,....

Btw,...... What killed the old motor,..??

Thanks, all!

I'll see how it behaves after a carb rebuild.

Old engine just got old, I had to pull everything out as the sump had rusted through. By the time I was going to replace pulleys, covers, and all done by a mechanic by the hour as I had no workshop, it was going to be only marginally less than a new short block, and it would still have had hundreds of hours on a raw water cooled block.

So, in went a new short block, and I had the anciliaries transferred over. Broke my heart, as I didn't have the means to store the old lump anywhere to rebuild and sell on.