Hey Fellas, silly question. Stock 454 Merc manifolds have one hose off thermostat housing to riser, and one to bottom of manifold.

These new CMI headers only have one hose to bottom manifold. Riser has a plug where a hose would go.

Do you run a 2 hose Merc thermostat housing, or tie in the plugged "riser" with a hose? Learning about the flow vs psi mechanics, but didnt want to make a water cooling error. This is old hat to you guys, so I apologize if it a silly question. 🥃

What what style header, CMI makes several

Just the E Tops for a Stock 454.

It won't let me post pics yet, so I added a few header pics in my gallery.

You need a Y to plum the two hoses together to the header.

https://shop.forcesinc.ca/products/l...less-steel-304

Yup, Y or two hose tstat housing.

[QUOTE=Precision;4894096] You need a Y to plum the two hoses together

Thank you Precision. 🥃🥃

Are you asking how to go from the 4 outlet to two because your E-tops have plugs?

If you have the stock 4 outlet the restricted ones should go to the top of the E-top, just change the plug to a barbed fitting. See if this picture helps.

Pull the plug out of the upper tailpipe and run the hose that ran to your manifold riser there.