25" pitch prop but what diameter? 1979 Aristo Craft Mercruiser 470

[bugdewde]

I have some literature stating that the 1976 (no info on 1979) Aristo Craft Nineteen with a 470 series Mercruiser (170 hp inline 4) and the MC-1 (Pre-Alpha) drive had a 25" pitch prop, but it doesn't mention the diameter. It even gives a part number (for '76) as 48-65480A4.

My question is: What prop originally came on the 1979 Aristo Craft Nineteen with a 470 series Mercruiser?

The prop currently on the boat is a Michigan Wheel Co. SMC-382 (15x25 cupped) that gives excellent performance for me, but is slightly bent and worn. Current WOT gets around 4k rpm (within the 170hp range of 3800-4200) give or take a few depending on load and trim.
I can not find an aluminum (affordable) replacement. Just wondering what the original prop specs were for the '79..... since I am continuing my prop search, might as well see what the original was?

I've found several 13 3/8 x 25, one 14.5 x25 and a few others here and there on the web, but I can't determine whatprop specs were originally on the boat. Anyone know?
1979 Aristo Craft Nineteen - 470 series Mercruiser

 

[Bamaman1]

Re: 25" pitch prop but what diameter? 1979 Aristo Craft Mercruiser 470

Going online, I see is a 23 pitch, 13.88" prop and it's a Michigan Wheel stainless model # 74975 @ $259.99. Separate hub is required @ $49.99. There is a Michigan Wheel Vortex 3 14" aluminum prop @ $99.99 (separate hub required) in 23 pitch.

When I had the same engine, I was running a 23 pitch stainless prop on about the same size boat as an Aristocraft, and it was quite fast on top end.

Both are listed at the Big O over in Fayetteville, NC.

 

[MaPaHa]

Re: 25" pitch prop but what diameter? 1979 Aristo Craft Mercruiser 470

I just learned a time consuming lesson on diameter (school of hard knocks). On a new build 17 foot F/S with an older 140 and no starting point I came up with a 21 high raker x 13.875 with heavy cupping I thought would be close. It lugged way bad and wouldn't come out of the hole. I then found a 21 standard rake x 13 with light cupping and when you looked at them it was a much smaller prop. The results were it didn't make any difference at all on the rpm but I did lose a few mph and it didn't have the bite as much at top speed and couldn't trim as much. Overall, I don't think the loss of nearly an inch diameter did anything. I think losing the rake and cupping lost my speed and bite.

I think anything close on diameter would be fine.

 

[jestor68]

Re: 25" pitch prop but what diameter? 1979 Aristo Craft Mercruiser 470

You should have a prop shop fix up that prop, as it's no longer made.

Aristocraft Boats. 850 Mayfield Rd, Alpharetta, GA 30004 Phone: 770 475-5455

I understand they have a club.