Help! Chrysler prop question!

[Racoon]

I have a 1971 Chrysler 45 h.p. outboard. Serial number is 454BC.
The 'Owners manual' says it has a 12 and 1/2" pitch prop.
A 'Service manual' says it has a 13 and 1/2" pitch prop.
I need a new one, which spec. should I trust?
(Other particulars are: Aluminum Alloy, 10 and 3/8" diameter, 3 blade, Right hand rotation )

Of interest the owners manual and service manual both say that the 55 h.p. engine has a 12 and 1/2" pitch prop, I don't know if this has any bearing on the 45 h.p engine, but it seems odd that the larger engine would be at 12 and 1/2" and the smaller 45 h.p. would be 13 and 1/2", that is why maybe it was a misprint in the service manual, but I am worried about getting the correct pitch.
Thanks so much, if some one can help me!

 

[steelespike]

Re: Help! Chrysler prop question!

Have you checked carefully for numbers on your prop near the base of the blades or on the barrel.
Your prop size would depend on the size and weight of your boat, your typical load and activities.
Do you know the gear ratio?Do you know your present wot rpm and gps speed.
It's not likely a 13 1/2 as that is the highest listed and would likely appear on a light fast boat.

 

[Frank Acampora]

Re: Help! Chrysler prop question!



The 35, 45 and 55 all used the same lower unit and gear ratio. Horsepower was developed at different RPM so all engines used the same props. Depending upon the size of the boat the engine is mounted on, the pitch would vary from 11 1/2 (for a bigger or heavier boat or load) to 13 1/2. Greater pitches are available for very small boats but are a little more difficult to find. For example: This little 10 foot racer has a Chrysler 50 on it. It uses a 10 1/2 X 15 1/2 pitch old school bronze two blade prop. I had to search the auctions for a couple of months to find it.

You can buy a new 10 3/8 prop for any early Force 50 here on iboats or (better) you can buy a used one on the auction.

If you know someone with a press or have the capability of using a press, you can buy an Evinrude (OMC) prop and press in a Chrysler hub. The props for old Evinrudes are exactly the same with a different hub. That is what the last photo shows.

 

[Racoon]

Re: Help! Chrysler prop question!

Have you checked carefully for numbers on your prop near the base of the blades or on the barrel.
Your prop size would depend on the size and weight of your boat, your typical load and activities.
Do you know the gear ratio?Do you know your present wot rpm and gps speed.
It's not likely a 13 1/2 as that is the highest listed and would likely appear on a light fast boat.

Wow, there it is imprinted on the prop itself! It says 10 3/8. and 12 1/2" pitch! Thanks for the sage advice!