I just finished rebuilding the Holley 4160 750cfm (vacuum secondary) that was in my boat. The kit came with a 6.5 power valve which I installed. Then I noticed the power valve vacuum port was blocked off. Is this typical for a jet boat or should i be using the vacuum port. The main jet sizes are 76. The 460 it was sitting on ran fine with no hicups and is currently being rebuilt.

-Steve

Its the Holley 0-9015-1. Marine version. It has two vacuum ports on the throttle body. One to the pcv valve and the other I beleive is the vacuum port for the power valve. There is also another vacuum port on the side of the metering body just above the idle mixture screw which is also blocked off. I think that one is for the advance on the distributor.
I dont have the cam size yet for the motor but it will have flat top pistons with about 9:1 compression.

Its the Holley 0-9015-1. Marine version. It has two vacuum ports on the throttle body. One to the pcv valve and the other I beleive is the vacuum port for the power valve. There is also another vacuum port on the side of the metering body just above the idle mixture screw which is also blocked off. I think that one is for the advance on the distributor.
I dont have the cam size yet for the motor but it will have flat top pistons with about 9:1 compression.

A true marine carburetor may have a port for a mechanical fuel pump vent hose.

There should not be a port for the power valve externally.

Looking up the specifics on that deal right now.

GT

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Yes it did seem to be a little rich above idle. There was some soot on the transom that seemed to be getting worse over the years. I just thought it was because the engine was getting tired.
Yes 10.5 seems like it would be open all the time.
I guess what im not sure about is how this power valve is actuated.  From what I understand it is one of the vacuum ports on the carb. However all of the vacuum ports are plugged on mine (except for the pcv). Would this cause the power valve to never open?

Yes it did seem to be a little rich above idle. There was some soot on the transom that seemed to be getting worse over the years. I just thought it was because the engine was getting tired.
Yes 10.5 seems like it would be open all the time.
I guess what im not sure about is how this power valve is actuated.  From what I understand it is one of the vacuum ports on the carb. However all of the vacuum ports are plugged on mine (except for the pcv). Would this cause the power valve to never open?

The only way it could be an external port is if the carburetors are boost referenced, like for a blower or turbo chargers.

The vacuum signal comes from the back side of the valve in the metering block, basically from a port in the throttle plate.

Depending I how you use the boat, I think I personally would drop the power valve to a 4.5 or a 5" and see what it does.

Be sure to oil up the gaskets with engine oil when you put it back together. It makes the gaskets removable without damage and prevents shrinkage.

Grab the spring kit and a couple of power valves, once you get the floats set up and the idle working right, you only need to do that once. Replacing PV and the secondary springs does not necessarily mean you have to go through that again.

It shouldn't have to go into enrichment until about 3,800 rpm or under a hard acceleration.

I think it would be run better and get improved fuel economy when not running balls out.

GT



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Thanks GT. That makes sense. I guess the port i was confused about may have been for an automatic transmission or something like that.
Speaking of float level. How do you tell if it is set too high or too low. The instructions said to put them right in the middle of the bowl while holding them upside down.