Holley 4-BBL Rebuild for 5.8FL

[LoyolaCub68]

Hey everyone,

I have a 4-BBL Holley of a 5.8FL VP that I'm currently rebuilding. I'm having a couple of issues as I'm cleaning out quite a bit of corrosion and junk.

1. In the picture I attached, this is the electric choke module. Is this a check ball that is supposed to move? If so, this thing is frozen solid.
2. Does anyone know which power valve I should be using? The Holley rebuild kit came with a 6.5" but the one in there was a 2.5". Not sure if it's the right power valve as the original owner used a Sierra rebuild kit previously and I heard those kits don't always have the right parts.

Thanks for your help.

 

[Scott Danforth]

you need either the 2.5 or a 3.5 power valve on a boat. 6.5 would be for a car or truck.

I believe that is a staked plug in the choke housing.

 

[LoyolaCub68]

Thanks Scott for your help!

 

[Maclin]

Yes, that ball is staked into a recess that has some small venting you cannot see from the front, the ball acts to regulate the volume and speed of air in/out of the housing.

And I concur on the 2.3 - 3.5 power valve.

A speed shop may have the 3.5's in stock , probably can order anything else.

 

[LoyolaCub68]

What would be the harm in using the 6.5" power valve? The only reason I ask is because in doing some research I came across a Mastercraft forum where a lot of those guys were running a 6.5" in their 5.7's. I have a 5.8, would I risk running too rich?

 

[Maclin]

Cruise economy and throttle response are affected by power valve tuning. Too high of a power valve can produce an over-rich condition in the low to mid throttle cruising.

 

[Scott Danforth]

What would be the harm in using the 6.5" power valve? The only reason I ask is because in doing some research I came across a Mastercraft forum where a lot of those guys were running a 6.5" in their 5.7's. I have a 5.8, would I risk running too rich?

these guys probably do not have a clue as to Holley carbs or how the power valve works. Most Mastercrafts are not run at idle, however under load. once on plane, and off idle, the power valve is no longer used. it is for the transitional load pickup between idle circuit and mains. As Maclin pointed out, too big a power valve, and you run rich just off idle transitioning to mains.

run the 2.5 or 3.5. Its what I ran with my warmed over 5.7, its what I will run with my stroked 7.4. the size of the power valve has nothing to do with engine size, it has to do with manifold vacuum coming off idle.

 

[jimmbo]

The power valve is only a switch changing the air/fuel ratio, held closed by manifold vacuum. It needs to be closed at idle, it may open during the initial off idle movement, however since the mains aren't yet flowing it doesn't matter. Any leanness at this point is supposedly covered up by the accelerator pump. Once the fuel is flowing thru the main circuit the power valve may or may not be open depending on the manifold vacuum During most cruise condition manifold vacuum is high enough to close the valve. Opening the throttle more may or may not open the power valve, it depends if manifold vacuum drops below the opening value. if it does open, the mixture will richen and as the engine speeds up manifold vacuum will rise and if it gets high enough, close the valve again At flat-out WOT vacuum should be below the opening value, if it isn't the engine could end up running lean. A carb that is too small can result in a manifold vacuum at WOT high enough to close the valve. Usually doesn't occur with a 4 barrel. A 5.8 is not going to need more than about 450 cfm even at 5000rpm