Prop Question-'72 Merc Inline 6

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IBrokeMyFreakinNeck

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I need a prop for my 1972 Merc Inline 6. The one I'm looking at is a Mercury Quicksilver SS 23P 3-blade prop off of an older model Merc Inline 6. The guy told me that it should work, but I would like to get some feedback here first. It fits a 15 spline, but I don't know what mine is. I would appreciate any advice.
 
K

Kenny Bush

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Re: Prop Question-'72 Merc Inline 6

You will find a lot of props that will fit. In those days, they used a bunch of 2 blade props. I think the 23 pitch is too high(unless your boat is very light). Also in those days, horsepower was rated at the engine instead of the prop. This reaffirms my decision that the 23 is too high. Most of the 90hp and the 115hp I have seen have 17,19,& 21 pitch props. I have a couple of 2 blade 23' props, and I have never been able to use them. I always had to prop down. What kind of boat and weight will this prop be used on?
 
S

Spidybot

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Re: Prop Question-'72 Merc Inline 6

There really only are a few different prop hubs within Merc's 6-inline range.<br /><br />If they look alike (hub length and thrust spacers), and they slide onto the shaft, thay work.<br /><br />On the hub you find numbers id'ing the prop. Let me know and I'll look it up in the Merc prop catalogue.
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

It's a 16 foot Tide fiberglass. I don't know the weight. It has new decks, seems pretty heavy.
 
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Spidybot

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Re: Prop Question-'72 Merc Inline 6

Get the numbers from your prop and I'll cross ref. it to the other you've been offered to see if it fits.<br /><br />Next we'll discuss if it's right for your use.
 
K

Kenny Bush

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Re: Prop Question-'72 Merc Inline 6

I do not think the 23 will work at all..... I think a 19 pitch would be a good start. If you can maintain WOT (per manual specs) with no problem, then you could move up to a 21'. The only way a 23 would work is if it has vents(to help spin out of the hole) or is a smaller diameter. As posted earlier, get the old prop numbers(if you were happy the old prop) and we will match up. You should see a "17p" or "19p" stamped on the hub(usually next to MFG data) or get the whole part number and we will crossreference. I like the 3 bladed stainless quicksilver, but make sure your engine will spin it OK out of the hole and WOT.
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

Well the motor didn't come with a prop, so I don't know what was on it, or whats supposed to be on it. I'm basically just looking for one that will work, but sounds like the 23 pitch won't.
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

UU,<br /><br />Can you check this prop part number and see if it will work.<br /><br />48-32390 A3<br /><br />It's a Mercury Quicksilver 3 blade, 14 diamater, 15 pitch prop.
 
S

Spidybot

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Re: Prop Question-'72 Merc Inline 6

Now, that's a good ol' number...<br /><br />Had to browse through a pile of old catalogs, but here goes:<br /><br />It is a 3-blade alu prop with a 13" dia and 15" pitch. Recommended use for 19'-22' boats depending on hp, weight, hull design etc.<br /><br />The mentioned prop fits these models:<br /><br />650 (2:1 gear) 1961-70<br />650 (2.3:1 gear) 1961-70<br />700 thru 1976<br />800-850 (2:1 gear) thru 1977<br />800-850 (2.3:1 gear) thru 1977<br />900-950 thru 1977<br />1000-1100-1150-1250 (2:1 gear) thru 1977<br />1150 (1.78:1 gear) thru 1977<br />1350 (1.78:1 gear) thru 1977<br />800-900-1150-1400 year 1978<br />80-90-115-140 year 1979-1982<br />1400-1500 (2:1 gear) thru 1977<br />1750 (2:1 gear) 1976-1977<br /><br />For these ranges you may find pitches from 10" to 25", 2-, 3- or 4-blade, alu or stainless.<br /><br />It even matches props for the old Mercruiser 80 and 90 (1962-1963) <br /><br />To get an approx. idea you can play with<br /> http://www.mercurymarine.com/prop_selector <br />or<br /> http://www.dorthe.homepage.dk/speedpropcalculator.xls <br /><br />For 16' and some 100 hp (your hp was not measured on shaft and equals a somewhat lower value on those modern motors that are), boat, motor & load gw around 1800-2000 lbs I'd suggest you start out with 17" or 19".
 
Clams Canino

Clams Canino

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Re: Prop Question-'72 Merc Inline 6

I agree, a 17 pitch is best place to start. The 15 might be usefull for pulling up slalom skiiers though.<br /><br />You should have a tach, select the prop pitch that will let the motor make at least 5500 at WOT.<br />That doesn't mean to run it there - LOL, they cruise nicely at 4100. 6000 is the MAX a prop should make on the inline 6.<br /><br />-W
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

UU,<br /><br />I tried the two links but didn't have any luck with them. If you don't mind, I have another prop number to see if it will fit my motor.<br /><br />It's a merc 2 blade, 19 pitch, model no. 48-31456-19<br /><br />Thanks,<br /><br />Billy
 
S

Spidybot

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Re: Prop Question-'72 Merc Inline 6

Weird - the links works OK..<br /><br />That prop is not known..<br /><br />However, the system indicates thet you're right as<br /><br />The part: 48-31454A3 is a 21". It has been substituted with: 48- 77346A45 which is stated to be for Flo-Torq II or III.<br /><br />See www.mercurypartsexpress.com as they can identify most of not too old part numbers.
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

Originally posted by UU:<br />Weird - the links works OK..<br /><br />That prop is not known..<br /><br />However, the system indicates thet you're right as<br /><br />The part: 48-31454A3 is a 21". It has been substituted with: 48- 77346A45 which is stated to be for Flo-Torq II or III.<br /><br />See www.mercurypartsexpress.com as they can identify most of not too old part numbers.
Click to expand...
The links worked I just couldn't get any results. Thanks for your help.
 
C

cobra 3.0

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Re: Prop Question-'72 Merc Inline 6

I'd stay away from a two blade prop unless you plan on using the boat alone....not enough hole shot. Most two blades were designed purely for speed.<br /><br />I agree the 17" pitch will probably be best, but the 19" should also be fine.
 
I

IBrokeMyFreakinNeck

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Re: Prop Question-'72 Merc Inline 6

I'm very frustrated trying to find out if the props I look at will fit my motor. I enter the part numbers at merc's part express but I always get errors.<br />How can I find out if the props will fit my motor for sure? I can't ever seem to get a definite answer. Help!
 
M

mellowyellow

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Re: Prop Question-'72 Merc Inline 6

walk into your local merc dealer and he will know.<br />might even be willing to let you try it and exchange <br />it if you are not happy with performance.
 
S

Spidybot

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Re: Prop Question-'72 Merc Inline 6

The previously listed motors fits the prop you stated. If that one fits your motor so does any prop for any of those mentioned on the list.<br /><br />What prop dimensions are right for your setup and use can be detected only by testing and watching a tach.<br /><br />If you turn to a good prop shop they'll lend you props for testing to help you chose the right one.<br /><br />I got the info from an old Michigan catalog.
 
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