Exhaust Riser Questions

[76SeaRay]

So, I have a few of questions on exhaust risers came up while researching info on them a bit:

1) I see where there are various riser heights and spacers. Are these only to adjust the height of the exhaust exit or do they have some other effect such as related to additional cooling?

2) I ran across two different types of riser gaskets. One with a very small hole on one port (restrictor gasket) and the other has a large full port opening. What is the application of each of these gaskets so I know which one to use?

3) Is it a good idea or a bad idea to have the exhaust manifolds and risers "hot tanked" at a local machine shop?

Thanks...

 

[AShipShow]

You should replace the risers with the same size that you currently have in the boat (assuming everything is factory). The different heights are meant to make sure the waterline of you're boat does not get higher than the high point of the exhaust. If you're exhaust was too short, the waterline would be height enough that it could flood your exhaust ports.

Someone will probably follow up on which gasket to use, I can't remember, but I think I recall you are supposed to use the restrictor gasket when raw water cooled and the open one is for closed cooling, but don't take that to the bank... Someone smarter will be by soon.

 

[76SeaRay]

Thanks, I have an Alpha One Gen One with the bull horn exhaust out the sterndrive so it sits pretty high without extensions on the risers.