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-   -   30' cat single hp500 WOT 3500 no more? Need help (https://www.offshoreonly.com/forums/general-q/328154-30-cat-single-hp500-wot-3500-no-more-need-help.html)

tdpb2008 07-07-2015 08:47 AM

The secondary's are opening, and it get up on plane quick until 3k then falls on its face, fuel is good I put in 100 in each side of 91 non ethanol

tdpb2008 07-07-2015 08:49 AM

We did pump accelerator pump by hand and it did pick up some so I am told the carb is an 850 but I have doubts of that I'm thinking it may have too small of a carb but not sure till I try another

airjunky 07-07-2015 10:26 AM

Even with a 750 it shouldnt throw in the towell at 3k sure both bowls have gas in em ?
Better be hanging on when when you throw some enrichment on this at 55mph the speed jumpnmight tangle you in the drive belts or have ya grabbing a handful of distributor cap at wot.
think your onto something though . If you can still see the float levels your on easy street. Hope the engine hatch has been pulled for your convenience ..

tdpb2008 07-07-2015 10:33 AM

We pulled the hatch off and my buddy pumped the accelerator pump and it picked up so I think the carb has something to do with the problem and I do think the prop and drive is a little too tall for the setup in the boat, just need some re assurance and I hope I'm on the right path lol

Griff 07-07-2015 12:07 PM


Originally Posted by tdpb2008 (Post 4326553)
Checked the tack to a timing light and it's within a 100rpm of each other

What is total timing set at though???

tdpb2008 07-07-2015 12:50 PM

I believe he said it was 32*

airjunky 07-07-2015 01:45 PM

If your standing on the throttle as its trying to get past 3500rpm you shouldnt be able to pump anything . Might be time for a known good carb swap , you can take a peek at the throttle plate stampings while old one is off.
sounds like someone may of slapped something together to get you in thier old boat
this is a holley double pumper with a r list number true?

GPM 07-07-2015 02:12 PM

Any chance the fuel pump or filter is causing the problem.

SB 07-07-2015 02:32 PM


Originally Posted by airjunky (Post 4326690)
If your leaning out its not good for the motor long term

Nor short term.

Many people that sell a boat with a different motor than what they had in it, don't tune it.

Furthermore, how many boats get sold that the owner takes off their fvorite prop and throws ome other on it? A ton.

Even if running good, which it isn't, I'd be verifying carb list # and pulling it apart to see what jetting and etc is in it.

Obviously, checking timing and all other ignition parts too.

Trusting someone or assuming someone left you something correct, is a quick way down misery lane.

GPM 07-07-2015 03:16 PM

[QUOTE=tdpb2008;4326494]I have a 30' cobra terminator cat I had just bought it has a hp500 500-540hp it has a bravo 1 1.36 ratio and a 26p bravo prop, at WOT I'm getting between 3500-3800 rpm max @ 55-58mph I'm not sure if I have a timing issue fuel issue or if it needs a 1.50 ratio drive it planes out strong then falls on it's face at 3k rpm

Looking for some help

I don't think the 1.50 will fix your engine but I would bet it will be a better all around gear for that application.


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