I am putting 496 exhaust exhaust manifolds on a closed cooling 454 and need some information on plumbing the cooling system. I know guys on OSO have done this mod and was wondering how they plumbed the cooling system to there manifolds. I don't have to worry about the oil filter or any linkage just the plumbing, any thoughts or suggestions are appreciated Jamie

GOOGLED "mercruiser closed cooling system diagram" AND CAME UP WITH MULTIPLE DIAGRAMS

Ayuh,..... Do ya have heat exchanger enough to include the exhaust manifolds into the freshwater side,..??

personally i feel you should just closed cool the engine and leave exhaust manifolds raw water. although all my experience is with wet joint stock style stuff. the manifold to riser block-off is where the most leakage problems arise. but those gil 496 manifolds being dry joint might not be such an issue. but plumbing is a lot simpler with running the exhausts raw water.

I have aluminum 496 exhaust on my 502 and it was a pretty easy install..... I only used 1 of the 2 riser water inputs and it provides plenty of cooling....... I am in salt water using lots of aluminum engine components so closed cooling is a no brainer..... You will like the results.... Go for it!

I used the monitor products system and you can go on their website for a detailed diagram of the installation.....

Did you use both water outlets of the manifold or did you also block one of manifold water outlets ?

Andre

Also just one....... I have never see more than 180* even running hard in the florida heat!

How the heck did you block off the outlets!!!!? I have been searching for stuff for the last week and can't find anything. . I'm trying to run it like you did .. I had ran both hoses coming from the thermostat housing to the lower side of the manifold but while testing it started to overheat..
Please help
Thanks !