Exhaust riser gasket for 260 Alpha...

mohead1

Petty Officer 2nd Class
Joined
Jun 18, 2011
Messages
134
Removed the manifolds on the '88 260 Alpha today for inspection, one was weeping water near a spark plug. The riser/elbow gaskets are restricted instead of full flow...any reason for that, and what if I use a full flow non-restricted gasket here? The two tiny restrictor holes in the gasket Im sure will get closed up my debris and such....
This motor does have a separate hose to the riser/elbow from the water pump besides the one going into the bottom of the manifold. Doesnt make sense to me, I would think you would want full flow to the riser up from the manifold itself.
Also, turns out the one manifold must have suffered freeze damage at some point. Hairline crack just above the curved area for spark plug clearance.....it was dripping everynow and then so I didnt fool with it. I ordered a completely new set of manifolds and elbows....
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Exhaust riser gasket for 260 Alpha...

Yes there is a reason. Flow control of the water. Use the gasket recommended by Mercruiser. The did the engineering and testing of the system and found the gasket with the restricted ports worked best in some applications.
 
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