4000 Max RPM w/ 542??

How do you know the cheap tach in the boat is accurate?

What is the timing advance at 3500rpm? Should move up to 30-35 degrees. My advance mechanism was stuck and preventing my 351 from turning over 4k.

Warm it up and see if it will spin over 4000rpm while on the trailer or in neutral. If it won't, you don't have a prop issue

My brother had the 351W in a 1988 Supra, 240 HP if I remember right.
That engine would not spin over 4,200 at 42 MPH and only had a 13x13 prop.
The Supra was just heavy and did not move fast in the water.
Ran perfect, we checked everything and it was tuned great, he wanted 4,600.
The previous owner had a 13x12 prop on it but it was damaged so we did not try it.
The boat just had more drag. My Malibu with a 250 HP 350 and the same 13x13 spun up to 4,600 and had almost 5 MPH more speed than the Supra.
We never checked for wet foam in the Supra, did not know about that back then.
Does the Martinique normally run the same RPM and Prop as a Ski Nautique?

Chris,
I understand your thought but, it doesn't take much for an engine to rev up over the 4K even if there's something wrong with it. You could pull half of the plug wires on an 8 and without any load get it to spin up over the 4K.

MrMcD wrote: My brother had the 351W in a 1988 Supra, 240 HP if I remember right. That engine would not spin over 4,200 at 42 MPH and only had a 13x13 prop. The Supra was just heavy and did not move fast in the water. Ran perfect, we checked everything and it was tuned great, he wanted 4,600. The previous owner had a 13x12 prop on it but it was damaged so we did not try it. The boat just had more drag. My Malibu with a 250 HP 350 and the same 13x13 spun up to 4,600 and had almost 5 MPH more speed than the Supra. We never checked for wet foam in the Supra, did not know about that back then. Does the Martinique normally run the same RPM and Prop as a Ski Nautique?

The Martinique is a heavier boat, and has a deep vee hull. And, at 32 years old may have a couple of pounds of wet foam in it too. It can use the same prop as a SN, but is usually better with a lower pitch prop. The SN's normally run Acme 540's, or 13x13's. The Southwind's and Martinique's are better off running the 542's (13x12 I think) in my opinion. But, there are guys on here who have forgotten more about props than I will ever know and they may have a different view. I know my prop isn't perfect, and I suspect it is part of the equation of the rpm situation. I just can't find any glaring issues with the engine. I thought the advance spring situation was the culprit. Got it fixed, and no difference.

As Tim mentions, I should check it out with the GPS, which I have not done yet. I will add that to the list to things for check for next year. Now I will have to figure out if my cell phone has gps. I'm not the most tech savvy boater on the lake (old).   

If you brought the speed up slowly and let off slowly 4,500 would not be an issue even running on the trailer but I do not think you would learn any new information.
It would be a waste of time.
Your issue is making horsepower and torque that can spin it above 4,000 in the water under full load. If you had a known good spare prop to swap from a boat that is known to spin that prop to a higher RPM you would have a more realistic test and maybe learn something.
To verify the carburetor is opening all the way you can take off the air cleaner and open the throttle all the way at your helm and see if the plates in the carb are 100% open on the front two barrels.
With a volunteer driver and smooth water you can test vacuum secondary. You can open the motor cover on the water, have the driver run wide open see if the four barrel opens, you can watch the linkage and hear the secondary kick in. You can take one finger and see if you can press up on the diaphragm and get any more throttle from the secondaries.
They are either fully open or not. Vacuum operated are hard to test.
I had an old Holley that was not opening the secondaries.   This test found the issue, A carb repair fixed it.

Our Holley experts will give you good rebuild advice. I will share that my Holley that had issues opening the secondary ended up being a small Oring or gasket where the Vacuum diaphram housing screwed on to the carburetor body. There was a small Oring or Small Gasket, I do not remember which but that part was bad keeping vacuum from getting to my diaphram to open the secondary.   Once found it was an easy fix and never troubled us again.

It’s a cork gasket - go on holleys webbsite and see if it’s available without having to buy the complete kit

davidg wrote: I'll give that a try Gary. Thanks! By the way, you still a resident of IL? Based on some recent posts, couldn't tell if you were getting the hell out, I mean, moving out of IL.

6 months and 1 day in Florida puts you in a better tax bracket.

18 bucks from Summit for 20 of them, or if you can verify if the size is the same 2.00 for 2 for Quickfuel ones

Can't quite tell from your pictures if you have the housing with a small orifice in the sensing line of if it has a small ball check that resembles a BB in the sensing line.

It's easy to accidentally lose the little ball when you take the cover off, is why I mentioned it.

It's hard to lose the orifice though

First picture shows ball check, second picture shows the orifice in place of the ball check.





Since you have to take the choke housing off the main body to get the secondary housing off, how's the little gasket between the choke housing and the main body ?

That would be in the next picture

I could send one of those too   

yea my biggest expense is property tax, luckily it still can be deducted on my income tax. You have to do your homework before blindly running from taxes as some locations still have goofy taxes like personal property or high license and transfer fees. For example Illinois just raised the boat registration fee to 60 for 3 years, here in Florida it’s 28 a year and I’d have to pay to have the title changed over as well. If I were to change residency I would loose my homestead exemption on the property I pay the highest on as well.

They'll be on the way soon