Engine placement

[stupidbaker57]

I have an 18 ft Rayson flatbottom that I am restoring. The engine has been changed from what ever it was to a 383 chrysler. The stringers were rotted and swiss cheesed from all the different holes that weren't being used for years and have been replaced. I will be putting the engine in soon but would like to know how to determine the engine placement. I could go by the length of the drive shaft and the engine will be just about where it was when I bought it, but is it in the best place for this boat? I would like to be able to run in the 70-80 mph range. The engine will have an estimated 500-525 HP.

 

[AzGeo]

What has happened to the strut, shaft angle and V-drive placement ? Are they going back in at their original positions/angles ? I feel that there is a great difference in re-rigging any V-drive when choosing between 8-9-10 degree shaft angles. I would start with 'where the prop will be', (from the transom and the end of the plates)then 'what shaft angle', and then engine weight. As I recall, wedge/late Hemi Mopars are quite long VS a BB Chevy, so I might say "36 inches from the transom" but actually your motor would be 34 1/2 inches. I also feel that 'lots of details make the whole job end up better', so please give what info you have and then we can tell you what to 'look, measure, and learn about'. "Most V-drives that float will run, very few make the effort to make them RUN GOOD".

 

[stupidbaker57]

Here;s what I have. From rear of strut to transon 15 inches. to end of plates, 24 1/2 inches. The shaft is 12 degrees. The engine block is the same size as a Chevy at 24 inches without the ederbrock plates at each end.

 

[AzGeo]

The strut says 12 degrees on it ? Or is the V-drive 12 degrees ? What kind of condition is the propshaft in ? If you want the boat to run 'very good' you want the prop shaft angle down around 8 degrees to the keel line of the hull. I asked about the shaft condition because you will need a longer propshaft if you lower the shaft angle. If you have 10 or 12 degrees of shaft angle and 'just want to put it back together' the way it was, I'm sorry I can't (won't) help you. As the shaft angle 'goes up' the possability of the boat 'bouncing' and having a 'poor ride' increase. Also, just because the boat was "built that way", does not mean that it was ever correct or good. So if your block is the same as a Chevy BB, then any 'normal measurements' would apply, and no 'adjustments' would be required. Please advise as to 'actual shaft angle', then we can go forward, or not.

 

[stupidbaker57]

This boat was set up with back to back seating, so I assume that it was a ski boat. The strut has no makings on it for manufacturer or degree. I used an angle gauge on the bottom of the boat and then on the shaft. Subtracted one from the other and came out with 12 degrees.

 

[AzGeo]

WOW, I'm sorry you have so much shaft angle. With that much 'true' shaft angle and back to back seating you can just put the motor where ever you like. With it set up like that it will just require the plates to be 'slightly down' all the time. Sure use the driveshaft length to remount the new motor, and 'have fun'. My going 'on and on' about how it all needs to balance and work together would just be a waste of time, because none of that information will overcome the 'shaft angle' you currenty have. GOOD LUCK

 

[BadBehavior]

I have an 18 ft Rayson flatbottom that I am restoring. The engine has been changed from what ever it was to a 383 chrysler. The stringers were rotted and swiss cheesed from all the different holes that weren't being used for years and have been replaced. I will be putting the engine in soon but would like to know how to determine the engine placement. I could go by the length of the drive shaft and the engine will be just about where it was when I bought it, but is it in the best place for this boat? I would like to be able to run in the 70-80 mph range. The engine will have an estimated 500-525 HP.

Just curious, Is this a LP? Most of the LP's had 9 degree shafts. Do you know what model this RC is?

 

[stupidbaker57]

I've been told that the hull # is on the left stringer forword of the steering, but I have nothing there. I don't think this is an LP. The transom is about 24 inches high at the k plate.

I've measured the shaft and the casale and they're both at 12 degrees.
This is a 1970. Where would the hull number be, and if it has been issued a new number by california, where would it be and what does it look like?