Chrysler 35, model 3550

[tmbna66]

Just picked up a 1972 MirroCraft, 14 ft x 63 in aluminum boat. The only gauge on it is a volts gauge. The prop on it is chipped in several spots and has a hair line crack starting on a fin to the base. The prop size is 10 1/4 x 11. I found a 10 3/8 x 12 1/2 off of a Chrysler 35 horse with same amount of splines. Will this work? How will it effect take off, top end or handling? I use it to cruise around a small lake I live on, usually just myself and a dog, but from time to time I pull my 13 year old Grand daughter on a tube. I'm not looking to race around the lake but am wondering if this be would safe.

 

[Maclin]

This will be total guessing without any RPM or MPH numbers from your boat's performance now....

That ends up being quite a jump in pitch and the engine may struggle to reach top rpm's if indeed it does now.

I had a 15.5 foot trihull with a 55 Chrysler, and I experimented with props after the 11p that was on it began slipping on the hub. That boat was quite a bit heavier than yours is, so will not be a one-to-one comparison but can show what small jumps in pitch in the 10-12 pitch arena look like to a boat. A 12p was ok with just me in it, could get on plane though it took longer, and with any more passengers or gear sometimes it would not plane out. A 10.5p over-revved and top speed was noticeably slower. I ended up with an 11.5p for best all-around.

If your engine revs freely but does not over-rev with the 11p that is on there now then I think you need to stay in the 11p range, I think the 12.5p could cause the engine to lug and struggle in any of your uses, just my opinion.

Got any pics of the rig? I am a sucker for those years of Chrysler motors...

 

[steelespike]

I think the 12.5 would be too much. How is the present performance You may find a GPS on a cell phone for an accurate wot speed.
Strong hole shot? How does it react to added weight?
A prop shop could easily repair your prop and you could even ship it and repair for less than new.
Does it easily pull a tube?
The wot speed will help tell if the setup is working well.The motor needs to operate within its wot rpm rating.
Of course once established you can operate at whatever speed suits you.

 

[tmbna66]

The motor sounds good at wot and doesn't seem to struggle. With a 110 lb girl on the tube and me at 200 plus a 150 lb passenger it does feel to struggle if they put their feet down or sit in it. Just me and my 70 lb lab in it runs and sounds good. I've been around boats all my life and watched my Dad and Uncle go through props looking for that perfect one. Repairing it may be the way to go. Thank you both. Here's a video that may help.

 

[tmbna66]

 

[Maclin]

Nice rig tmb. Sounds like that is the perfect prop too, good luck and happy boating!

 

[Frank Acampora]

It does NOT need to be a Chrysler prop. You can look for Force props from before 1994 since the lower unit gear ratio and splines were the same. Chrysler 35, 45, 50, and 55 all used the same prop as did Force 35 and 50. Just be careful because there were two different Chrysler 35s and 55s. Be certain a prop you buy has the correct diameter and splines AND is thrust pin drive.

10 3/8 by 1 1/2 pitch would be about correct although 11 1/2 pitch would not be too bad. Just don't go higher pitch than 11 1/2 as it will load down the engine, affecting performance and right now you have marginal power on that hull.

 

[jestor68]

Propco Propellers still makes original equipment props for those early Chrysler motors.

Their web site shows sizes available.

 

[tmbna66]

Frank, did you mean to write 10 3/8 x 11 1/2 or 10 1/2?