86 Ambassador Questions

[bad61ss]

I took this thread from the members rides area and brought it over here because I have some new info.....
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bad61ss
posted August 11, 2003 10:17 PM
Nice pics you guys. I like the action shot, too. I took my Ambassador out yesterday for the first time and had a blast. I was running it with the 21P prop. It also came with a 22, but I don't think it's enough. I'll probably get another one soon. Any recommendations? 24?
Adios-
Greg
Posts: 11 | From: Vancouver, WA | Registered: April 17, 2003


Bill
posted August 12, 2003 05:31 AM
What ever you run for a prop, be easy on that dive so you do not grenade her. That is alot of h.p. for and older alpha.
2003 ZT 240 6.2litre/Bravo 320 H.P. 24p Bravo 1
Posts: 1232 | From: Davneport, IA | Registered: November 22, 2002



Eriktheviking61
posted August 12, 2003 06:31 AM
It depends on your RPM's at Wide open throttle.Should be about 4800. Unless the engine is "built" for more. Certainly it doesn't hurt to try something else but I'll bet that 22 prop is best for that boat.
Posts: 151 | From: Delmar,NY,US | Registered: December 15, 2002

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Well, I went camping up on Lake Billy Chinook last week and here's what I found:

86 Ambassador (20'), 350, Alpha I
Altitude: ~1000
Exhaust: Thru-prop
Prop: Quicksilver 21P
Weight: unknown. approx 20 gal fuel, just me (190lbs), anchor, spare prop, ski, wakeboard...
Top Speed (speedo): 53
Top Speed (GPS): 49
RPM: 4100 trimmed out & hooked up, any more trim caused cavitation.
Adding the bow cover and center windshield section didn't make more than 1 mph difference.

So.... I'm thinking that going with the 22P prop will decrease my RPMs and move me out of my max power RPM range? I know this boat is heavier than a stock 86 Ambassador, because the previous owner replaced all the wood in the boat with resin-over-pressure-treated boards, then glassed them into the boat, sealed edges with resin, and used a few layers of pretty thick matting. It's solid, but heavy. The shop that rebuilt the motor said it has ~300HP, but according to Mercury's website, it would have to weigh about 3800 lbs with the 5.7/AlphaI combo to go that slow. I know the weight from the 1986 brochure is 2600 lbs dry, but I wouldn't think that adding extra glass and (slightly?) heavier wood would add a thousand pounds, do y'all?

I'm stumped. I should have put on the 22P prop while I was there, but didn't because my RPMs were so low. I am sure I don't have a linkage problem because the secondaries are wide open. Does anyone have any recommendations on what prop to go to?

I just bought Corsa Captain's Call cut-outs and Corsa Silent Choice thru-hull silencer tips (all 4") and plan to install them all soon. Maybe the thru-prop exhaust and stock flame arrestor is killing my top end?

Any help would be GREATLY appreciated. I barely beat a 5.7 EFI Bluewater!! Luckily I didn't race the Eliminator or 330hp Crownlines that were down there...

Thanks!
Greg

[Eriktheviking]

Those RPM's need to be around 4800.The thru hub exhaust is choking the engine some but with a 19 Laser II Merc prop or something similiar it would really wake it up. Stock spark arrestor shouldn't be a problem unless its clogged with fan belt rubber. Gotta get those thru-hulls on there!

[bad61ss]

Hey thanks for the info. I'll check ebay today for that prop! I've got the exhaust parts and the boat here with me today at work, so I'll be able to start working during our standby time.

Also, do you know what cam and/or head combination works good with this setup (thru-hulls)?

Thanks again,
Greg

[Bill]

That 21 may be bad also. I have a 25p Mirage that I can turn at 5000 rpm's at 66mph. The rpop felt as if it had a vibration, so I tried another 25p Mirage. I could only turn that one at 4400 rpm at 60mph. No two props are the same. I do think you should have to go down to a 19, I would try a 21 mIrage first...

[bad61ss]

Hey Everyone,

Well, I finally got all the parts on the boat. I added the 4" thru transom exhaust via Corsa Captain's call diverters and GLM tuned exhaust manifolds from Dennis Moore. I also put on a 19p Laser II. I also added a wakeboard tower. I sent a picture to Chris to post, but I can send more of the engine. I had a friend build me some mandrel-bent 4" stainless pipes to connect the diverters to the 4" tips. It looks pretty cool and sounds cooler, but now for the bad news: I still can't break 60mph. The best I could do (speedo) was 58, with the same load as above in my previous post (plus 10 more gallons of fuel and the wakeboard tower). This really bugs me. Ryan posted that his 86 Ambassador with the 260hp 350 will do 63mph, and he was hoping for 70 with some other work. Does anyone have any other ideas about what might be going on?

Thanks,
Greg