riser height above static water line

[john everett]

I am replacing exhaust manifolds and risers on my 1988 bayliner ciera 2556 (5.7 cobra). The previous owner changed the original end rise manifold to a center rise and added an extension. The change required that the engine hatch be changed from flat to raised (box) and the cooling system moved to the other side of its bracket. conciderable trouble. Was there a problem with the factory riser height? Is there a spec for height of riser above static water line? I would like to go back to the original mainfold and riser and a flat hatch if there is no problem in doing so.<br />thanks for any help <br />john

 

[dmorley]

Re: riser height above static water line

Mercury requires a MINIMUM of 13 inches, but I don't like going with the minimum and there is probably a reason the previous owner went to all that trouble.

 

[john everett]

Re: riser height above static water line

13", don't I wish. Can't I be happy I have 10". U.S. marine was no help when I called to find out if they had a record of problems with their factory set up. They referred me to the people who purchased oem. A technical support person told me that there was no spec available. very frustrating. I agree that I should err on the more is better side.<br />Are there extensions for the osco mainfolds and risers that replace the original OEM parts? (the ones I already bought)

 

[chris in va]

Re: riser height above static water line

My 302 really needs to have a higher rise. I got hydrolocked last year because my flappers had disintegrated...and didn't know about it. The boat really is stern heavy.<br /><br />Consider it a good thing you have higher ones.

 

[denniz]

Re: riser height above static water line

Anytime your shutters go out you will have water injestion. Think of the backwash when you stop. John is your boat a cobra? or a merc? most of the bayliner package boats were cobras.

 

[john everett]

Re: riser height above static water line

my boat is a 1988 bayliner ciera model #2556. The motor is a 5.7 litre cobra. I live near Bellingham WA so I recently visited San Juan Engineering, the company that made the original heat exchanger. They are building me a new larger system that will cool the manifolds as well as the block with fresh water. hopefully this investment of 500.00 will pay off by not having to replace the manifolds as often. Of course, it wont save me any money if I get salt water sitting on top of a piston from having my risers too low.