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

Let me preference everything buy saying this is my 1st boat and its been a bit overwhelming.
I have a 1981 Correct Craft with a 351W/Holly 4bbl carb. I bought it off ebay thinking it was a runner, When I went to pick it up, it ran and sounded good. The next day she wouldn’t start, leaving me stranded in the harbor… I now have boat assist and a running boat… but want to make some upgrades (Car guy thinking) and 1 issue.

The boat has required extensive work… ~7K worth (Money spent… I’m sure there may have been a way to do cheaper but not what happened.) The boat has now had, new fuel filter, new battery cables, ignition rewired (Had a MSD6A wired in), installed a pertronix module, with the motor retimed, new cap, rotor, wires, plugs. 1 cylinder was 30lbs lower on the compression test so the heads were rebuilt and converted to hardened seats. There was a rear main seal leak and the engine came out for a new rear main seal. The carb was rebuilt (some rejecting) and a wedge placed under the carb as it was bogging off idle.

At this point the boat runs well… The Wedge seems to have helped the bogging of the motor though I have not done a sea trial to confirm. My concern is that it seems that the boat does not idle in gear low enough… If you set the idle to 600rpms is seems to run poorly. If I turn the idle up, I can put around the harbor slow enough. Once upon a time I was ok at setting up carbs, but am not at this point. I feel like the carb is either too large or poorly setup. The after its last adjustment it seems to run much better on the trailer, but have yet to try on the water.

Upgrades… Should I buy an Edelbrock and then make basic adjustments? I don’t need it for top end… really just want the ability to idle around and use on the lake.

Long term, I want to swap on an Edelbrock Al. intake, new pertronix flamethrower ignition and a gear reduction starter… The intake and start should shave 40lbs off the engine and gussy it up some.

As an aside, if there is a good carb guy in OC/LA area... who will tune the carb in the water, please please let me know... really could use the help.

Thank you,


Justin

Hi Justin. One thing that comes to mind right away is how are you setting the idle? In the water,in gear? 650 to 700 is what PCM recommends. Do you happen to know what size prop is on it too? Another thing you can do is call the Holley tech line and give them the list number off the airhorn, see pic below and they can tell you what the carb is. You need to make sure its a marine one and same with the starter. If your engine is an original right hand turning one you'll need a starter to match. Automotive engines turn left.

Holleys for the most part,thats what PCM put on them. But like everything there are a few who try to swim against the current,matter of fact there are a few who even have Chevy's in them too
By the way if you do have a marine carb and it's the right size for the engine,Holley can give you the factory jetting sizes etc and then you can check yours to see if someone has changed things,oem was a 600 cfm

Glad I'm not the only one in for way more than my Correct Craft is worth. I am in the LA/OC area as well. Where do you usually boat? Throw up some pictures when you get a chance too!

Bunch of ideas, sorry if not well organized.
Hey guys... RE where to boat... I’m not sure. I used to take my jetski on the ocean and that was a blast. I’m pretty sure I want to keep the boat freshwater.
Re: Idle mix vs idle set screw.. I haven’t messed with the mix screws. I remember how to do it well using a vacuum gage so I’ve ordered one. I agree that as I’m not farting with the setup a AFB is not wise money. I do think in time an Al intake will be done... The Edlebock intakes have always been a good replacement for cast iron... least on my trucks.
So re: Carb setup. An ideas? What the correct jets? What options I should consider on the power valve? The shop installed a wedge under the carb and seems to keep it more level. Once I have the jetting right and the power valve selected, I’ll turn my attention to setting the floats while the boat is in the water.
Any other issues to consider? What do you guys idle at in neutral or in gear?

justinsweber wrote: What the correct jets?

The main jets are 662's. I think that # means the diameter of the jet opening is .0662".

I'll have to strip down the carb further to find the secondary jet size. More info coming.

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

Apparently Holley called these close limit jets. The tolerances were kept tighter if the third number was added. For all practical purposes they are .066" jets like you said.

Thanks for the heads up. I couldn't remember if there were removable jets behind that plate.

I tried both power valves:

2.5 - waits longer to open (or enrichen) as engine load increases
6.5 - richens the mixture faster with less engine load than the 2.5

I didn't have a wideband AFR gauge, on so its really hard to say which one is better. It could of been all in my head, but the engine seemed to respond smoother with the 6.5. Try the 2.5, I think it comes with the rebuild kit from skidim.

Most everyone is happier with 6.5

If in gear on trailer (what ever we are defining as in gear) the idle should be between 600-700rpms under load. Ok... and what is the recomended timing?

The shop said they "fattened" the jetting. I plan to buy #66 jets. Should I get #68 for a "fatter" or more rich setting too just in case? I dont know if they drilled the jet or replaced it. Ill assume they did it wrong and will be plesantly suprised if Im wrong.

I need a version of that which I can do with the boat on the trailer... In the harbor Im close by... its drop and go... I dont feel comfortable doing that stuff in the harbor.

Anything on the trailer... Happy to try.

I wouldn't bother with the above procedure without a load. Put the idle mixture screws 2.5 turns out and dial back the rpm to 700-750. That'd be as close as I bothered to get on the trailer. Setting the mixture screws for max vacuum while in gear on the water and dialing back that rpm to 650 will still be required. I find you sometimes need to make small adjustments after this to dial in the no-throttle key starts.

You can unplug the PCV valve and use that input. I think you'll need a 3/8" x 3/16" reducer nipple to get the vacuum gauge hose on it.

PCV is constant manifold presure?

On a newer one there are. Original carb, use the Pcv port on the spacer. But I wouldn't get too hung up on adjusting for max vacuum if you're not going to put it under load.