New to the forum... needing some general advise.

Lots to fill you guys in on:
So the boat has gone to get new upholstery... looks great... Went with grey on blue. Converted the front seats to a bench to allow more comfortable seating. Teak deck was treated and looks great, new carpet, floors were solid… all in all looks great.
Re: idle mixture screws: There is a 1” phenolic spacer with a ~1/2” fitting that goes to the PCV. The hose is special… larger at the carb side and smaller ~3/8” on the PCV side. I placed 3/8” to ¼ adapter and used another adapter from ¼” to 1/8” to hook up the vacuum gage. (Is the Vacuum gage nipple 1/8”?) I plan to order a ½” to 3/8” adapter and get 2 new hoses and then get a 3/8 to 1/8” adapter.
Anyway… screwed the idle mix screws in all the way in and then backed them out 2 full turns. The engine started right up. ~700 RPM out of water. Vac was ~ 15. With some adjustment I got it to 17. Its starts right up and runs great.

So here is my concern. Engine seems great, but I noticed a rust spot between the head and the block on the alternator/passenger side. The boat was in salt water 1 time since rebuilding the head… new seats etc. Do I have a potential head gasket issue? Oh god I hope not.!!!!!!!!

Answers to your questions in bold font.

1.     What is the size hose that goes from the back of the carb to the PCV Valve?

3/8” hose. Go to the local auto parts store and look for the below part. It’s made by a company called Dorman. Leave one the three ends uncut. Cut one end for the 3/8” hose. Cut the last end for the vacuum gauge hose.



2.     What’s the good top speed? 40ish at sea level?

Other people can comment on this, but I think 45 is common.

3.     I want to get various jet sizes. Ill get a stock set as it was changed out. (No idea to what).

Yes, stock is 66. However, main jets will not have an effect on the idle mixture. They control mixture at full throttle (power circuit) and midrange. The power valve decides when the midrange ends and power circuit begins.

Unless you are going to hook up a wideband gauge (is not easy to do on ski boats) and fine tune for a 12.8 AFR at WOT, there is no need to go with jets different than stock.

i.     What’s 1 step richer?
ii.     What’s 1 step leaner?

The term “steps” is misleading.

Idle mixture is typically measured in mixture screw rotations (from the seated position). For example, 2-1/2 turns. More turns counter clockwise is richer.

Power valve is measured by the amount of vacuum needed to open the enrichment valve. For example 6.5 Inches of HG. The higher the number, less engine load needed to enrichen.

Main jet is measuring the diameter of the jet opening. For example, 66 jet is .066” diameter. The higher the number the richer the mixture.      

4.     The stock power valve is 3.5. Should I use stock or just swap in a 6.5?

Try a 6.5. Note, that your gas consumption will increase.

The boat ran well... I struggled to get it to idle low enough when cold. I couldn’t get it to idle really low when not hot. I got it to idle at about 700rms in gear, 800rps in neutral in the water when hot. I realize I need to get it even lower.
I wasn’t able to mess with the mixing screws as I could get the gage hooked up. I didn’t get the adapter fitting I needed to connect to the back of the carb... (Hose that goes from back of carb to PCV.) Its coming in and I have the vacuumed gage.
Questions:
1.     What is the size hose that goes from the back of the carb to the PCV Valve?
2.     What’s the good top speed? 40ish at sea level?
3.     I want to get various jet sizes. Ill get a stock set as it was changed out. (No idea to what).
a.     Stock is #66.
i.     What’s 1 step richer?
ii.     What’s 1 step leaner?
4.     The stock power valve is 3.5. Should I use stock or just swap in a 6.5?
5.     Any other parts you guys would order?
Thank you!!!!!!! I was super nervous that after all this money spent Id not have a boat that would work… seems it will all work out.

I plan to get the needed adapter fitting and a vac gage and take her to the water tomorrow and a tire kicking sessions.

Yes.

There are no ported vacuum connections on a marine Holley.

The port should be one the rear of the carb spacer plate. I believe the PCV valve connects to it (at least it does on my motor (351W).

Does anyone have a pic of where I can get manifold vacume? I dotn have the carb infront of me... Ill be bring to a lake tomorrow and dont want any suprises :-)

-Warm the boat up on the trailer

-shut the engine off

-Turn both idle mixture screws all the way in (clockwise) until they are seated or can't move.

-Turn both idle mixture screws out 4 revolutions (counterclockwise). Yes this is rich, but the engine should run.

-Hook up the vacuum gauge

-start the engine

-Adjust idle screw (not mixture screws) until the engine is idling at 800 RPM

-Turn each idle mixture screw a half turn at a time (clockwise). Take note on the vacuum gauge if the vacuum level drops.

-Keep doing this in half turn increments (clockwise) until you notice a vacuum level drop (or RPM drop).

-After you notice a vacuum level drop, turn the screw counterclockwise a half turn


When you get on the water after this, you will have to dial in the idle RPM in forward (prop spinning). If the idle mixture is off, it will be on the lean side. This is why its more accurate to set it when the engine has load on it (prop spinning, at idle, pushing the boat).

Also, keep in mind that if you have vacuum leak this whole process will be a waste of time. Carburetors are very sensitive to vacuum at idle. They need vacuum to pull fuel into the intake manifold. If there is vacuum leak, they don't pull enough fuel causing a lean condition. Make sure your PCV valve is closed at idle and there are no cracks in the PCV hose. Also, make sure your carburetor and wedge spacer is bolted tight to the intake manifold.

8 degree BTDC is a good start.

Try this procedure:

-Warm the boat up at the boat ramp, on the trailer, with the boat in the water.

-shut the engine off

-Turn both idle mixture screws all the way in (clockwise) until they are seated or can't move.

-Turn both idle mixture screws out 4 revolutions (counterclockwise). Yes this is rich, but the engine should run.

-Hook up the vacuum gauge

-start the engine

-Move the shifter into forward (into gear)

-Adjust idle screw (not mixture screws) until the engine is idling at 700 RPM

-Turn each idle mixture screw a half turn at a time (clockwise). Take note on the vacuum gauge if the vacuum level drops.

-Keep doing this in half turn increments (clockwise) until you notice a vacuum level drop (or RPM drop).

-After you notice a vacuum level drop, turn the screw counterclockwise a half turn.

Whats the in gear (Prop turning)?

Before you even mess with the carb you should check your timing. There should be plenty of info here on timing your engine.

Once timing is set:

1. Use a vacuum gauge. ($15 at harbor freight)

2. Put the boat in gear on the trailer at the ramp. You have to set the 600-700rmps under a load.

3. You have to set your screws for max vacuum.

Its pretty imparative that you use this method. Just turning screws until it sounds good won't work.

Thanks guys. Is the 6.5 the right power valve?
Anyone ever use off road floats?

66 is the jet size, not sure what the 2 means.

A 4160 won't have (replaceable) jets in the rear, it has a fixed plate.

skitique179: If youre willing Id love some aid in gettig the carb dialed in. Everyting else seems in order.

Thanks everyone!

justinsweber wrote: I’m reasonably inclined… new to boats. I forgot to add that the exhaust manifolds, upper and lower were rusted out and were replaced as well. I realize in 5K more than the boat is worth… but I’m hoping to have a runner at this point… seems I do. After this season, I’ll need new carpet, but that’s pretty easy. I guess I’ll get to reading regarding tuning the carb… do most on here keep with Holley carbs or go Edlebrock/AFB? Edlebrock let you change the metering on the fly… seems a bit more user friendly. Anybody sell a carpet kit? Thanks for the input... Ill post some pic tonight. :-).

I run a carter AFB on my Camaro. The engine is modified, so changing metering rods without empting the fuel bowls was nice during the tuning process.

However, if you are not modifying your engine set-up it would be a waste of money (in my opinion) to change from Holley to AFB. As Gary said, check the jet sizes and make sure you have the right size power valve. The Power valves in a Holley do the same thing as the metering rods in an AFB.

I've seen some discussion on what power valve to use, but I was happy with the 6.5 when ran a Holley on my boat.

If you want, I can post the correct jet sizes?