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View Full Version : engine swap . right to left rotation


tdix0073
07-02-2011, 07:09 PM
Hello. I purchased a 73 stars and stripes a couple months ago. I baught the boat with a bad motor (cracked block) and just recently had a newly rebuilt motor given to me by a friend. I believe my old motor was reverse rotation and the new one is regular or Left hand rotation as looking from the rear. My trans is a velvet drive 1:1 . I have read somewhere the switch from one rotation to the other is as simple as reversing the pump in the trans as the velvet drive will work for either style. is this true? If anyone has done anything similar i would apreciate any advice. thanks

ProStar Slalom
07-03-2011, 06:35 AM
Hmm...I can't help with the question, but I wasn't aware that MC ever used reverse rotation engines. I know correct craft did for years, but MC? Someone educate us please....

Jim@BAWS
07-03-2011, 09:02 AM
Hello. I purchased a 73 stars and stripes a couple months ago. I baught the boat with a bad motor (cracked block) and just recently had a newly rebuilt motor given to me by a friend. I believe my old motor was reverse rotation and the new one is regular or Left hand rotation as looking from the rear. My trans is a velvet drive 1:1 . I have read somewhere the switch from one rotation to the other is as simple as reversing the pump in the trans as the velvet drive will work for either style. is this true? If anyone has done anything similar i would apreciate any advice. thanks


Not that simple...

You are right reversing the pump will turn the transmission 180 out. But if you are running it that way you are not running it the way it was designed to be run.

Jim

tdix0073
07-03-2011, 02:23 PM
Do you mean the Tranny isnt meant to run that direction or my complete driveline. If i switch the trans pump and get a Lefty prop isnt that all i would have to do? what else is there

ski/hunt
07-03-2011, 03:21 PM
I'm just thinking out loud here--and I know very little about the SS boats but on my ps205 the rudder is off-set to comp. for prop rotation. If you change rotation wouldn't that cause some steering/ tracking issues??

1redTA
07-03-2011, 04:15 PM
swap cams, and anything else, in the new engine and run it the same way as your old one, it would be a lot easier

WilliM1940
07-03-2011, 10:49 PM
I am no expert, this link says swapping the pump rotation is all that is needed:

http://www.boatgears.net/VD.php

You may want to look at a velvet drive manual:

http://www.correctcraftfan.com/reference/manuals.asp

Note this is from a Correct Craft site. This particular site may be more to your liking for your question on boats the vintage of yours. Searches there should yield gold. There is a gentleman over there who sometimes drops by here named Eric Lavine who has a buisness rebuilding these things and dispenses information often. Fantastic Finish Marine I think. Good luck with the boat.

tdix0073
07-04-2011, 03:16 AM
Well i switched the trans pump around today to accept left hand rotation and dropped the motor and tranny in the boat. I plan to get a lefty prop and give it a try after i get the motor goin. If tracking issues arise or the boat doesnt ride level then ill try something different. Does anyone know if I could switch my velvet drive 1:1 for the pCm 1.23:1 trans to accomodate lefty engine rotation and keep right hand drive rotation at my prop. This sounds like the best solution to me. Does anyone know if the dimensions are the same as far as mounting points with the two.

Thanks everyone

tdix0073
07-04-2011, 03:17 AM
Well i switched the trans pump around today to accept left hand rotation and dropped the motor and tranny in the boat. I plan to get a lefty prop and give it a try after i get the motor goin. If tracking issues arise or the boat doesnt ride level then ill try something different. Does anyone know if I could switch my velvet drive 1:1 for the pCm 1.23:1 trans to accomodate lefty engine rotation and keep right hand drive rotation at my prop. This sounds like the best solution to me. Does anyone know if the dimensions are the same as far as mounting points with the two.

Thanks everyone