Power Valve

SS,

let me know where to send the beer.

12 Deg at idle.

13" vacuum from the Solid Lifter cam....lighter springs did the trick. Just throw the throttle down all the way with or without a skiier and she's a monster. Re-built 289 HiPo running to 5000 RPM with some left over...no big deal there...it's how it pulls to 3000 RPM that really makses it feel "CORRECT".

With heavy springs the metering rods weren't being pulled down into the jet so the adjustment at idle took place with the rods out of the jet. Probably the reason for the idle mixtures screws set almost all the way in.


I'll give her a few tanks of gas and check plug color.

Thanks for all your help!

First, put the vacumn guage on to see what you have at idle, a stock cam should be 18 inches mild cam will be 15 ,16,inches. and so on. If you are pulling a load the vacumn will be as low as 2-4 pulling a constant load.
You don't say what the cam specs are however you have high cylinder pressure.
Timming should be at least 32 degrees at 3000,you may have meant 12 at idle. The advance at idle will be whatever, giving the condition of the springs controling the weights.The most important is the full out timming.
If all these issues are correct it sounds to me like you are running out of fuel and when you back off it gets a chance to refill the bowl. Check fuel pressure should under a load at least 5-6 lbs. It may not be supplying enough fuel.
The carburetor boats get really hot under the engine cover and have a tendacy to boil the fuel, sometime causing a vapor lock. If this the case slpit the metal fuel line going to the carb and put a piece of rubber fuel line in.
The timming is a issue, fuel pressure is a issue. Take them one at a time and keep a record of what you do. Hope this helps, question what does the boat do with just you in the boat at WOT.

64,
If you have a lot of angle, a wedge will help, however you have other issues, I am sure you at one time or another this boat has run good.

SS201,

My Edelbrock is stumbling. It accellerates up to 3000 and then loses RPM and falls back to 2500. I then have to reduce throttle to regain speed.

I thought the rear jets (0.101) were too large, but smaller jets behaved the same so I guess it's the Primaries and engine vacuum.

My next step is to record vacuum and change springs???

How was your Edelbrock set-up?

Does yours load fuel under the Secondaries counterbalance weights? I don't have a wedge...do I need one?

Yes I have, they are great, just like the old AFB series.

A #6 machine screw inserted in the secondary cam arc just in front of the linkage rod always worked for me on a Holley. it's a lot easier than replacing a power valve, and you can adjust when you want the secondaries to kick in. It doesn't matter if they are mechanical of vaccum.

My carb is a N.O.S. Holley 4160 list #75009-1

When I called the Holley tech line, they said the original powervalve was a 6.5 for my carb, but I don't know what the original carb was.

Does anyone know????

What is the formula for sizing the power valve on a marine holley 4BBL carb?