Riser spacer help.
 

Long story about how the old race boat I have is set up but I use GLM aluminum exhaust and Merc's 4" Stainless risers. I need somem big spacers. The motors sit real low in the boat At the moment I'm using 2 six inch spacers stacked on top of one another for one motor and a 3 and 6 inch stacked on one another for the second motor (back motor is higher) just so water dont roll back up the exhaust and kill my motors.
Does anyone make a spacer that is 9" or a foot tall? The main thing is cost. I would think about having custom risers made but I'm sure they want an arm and a leg for them. Seems real simple but I'm not a welder or I would just make them my self.

if you happen to take the risers off for some reason i am prolly gonna need 2 sets of 6 inch ones.. il buy them from you if priced right thanks JASON

Keep in mind I have a friend who is a CNC programmer, but, I would talk to a local machine shop about getting solid aluminum stock and boring the exhaust and mounting bolt holes. I made some for my Gil's, using his program for the holes, then personally machined an angled top for correct pipe placement. worked perfectly, but again, did alot of the work myself, so no idea what it would cost for one time fab. worth looking into.

and no water passages thru spacers...ultimate dry joint.

That sounds great but my machine shop consists of a sawzaw and a hand drill and the budget for custom exhaust does not exist as of yet.
Maybe I can get Stainless Marine to make a donation to the race boat one day.

I was thinking maybe you could go to a machine shop with a spacer and tell them what you want, probably get a free estimate... but dereknkathy brings up a point I hadn't thought about... my Gil's are dry joint with a water hose to bypass the gasket/mating surface between the manifold and riser. I'm not sure if your GLM's are dry joint. if they are not, then having spacers machined would be WAY more involved than mine were, so sorry if I spoke too soon.

fixx
 

mark i still have 4, 6'' and 4, 3'' spacers for glm..

How about exhuast flappers and installing an airgap in the exhaust system , just an idea

Wex, They could be dry joint if needed. The GLM manifolds have plugged ports for water outlets.
JB, everything has to be water cooled somehow.
Fixx, I forgot about them. Do you plan on keeping them? Maybe a PM if you are looking to unload.