maxpower_454

My intake gaskets came with intake manifold exhaust crossover restrictors. Where do they go? Are they needed?

63split63

They block the passages that allow hot exhaust gasses to cross under the carb when the engine is cold and the exhaust heat riser valve is closed .
I would install them unless you plan to drive the car in severe cold conditions .

Bill

JohnZ

Make sure your heat riser valve on the RH exhaust manifold outlet is either gutted, removed, or wired permanently open before you install the blocking shims, or the RH exhaust gases won't have anywhere to go.

maxpower_454

Ok, so I think I figured out that the riser valve restricts the exhaust flow through the RH manifold and forces more of it through a port in the head or something that crosses over through the intake to the left hand side. I think my RH exhaust manifold has the valve removed and the hole blocked off in the plate.

Would the restrictors matter at all if they were installed or not in this situation? I'm thinking not and maybe I want to block it off completely? The shims I have just restrict the flow. They have a hole in the center to let some through. Does anyone sell block off plates or should I just make some out of sheet metal?

PAmotorman

block of plates should be stainless steel so they don't burn thru. the ones with holes in are for engines with the choke heat tube in the exhaust crossover passage of the intake manifold to make sure the heat tube gets hot

856666

Maxpower,

The reason to block them off is to prevent carburetor percolation due to heat from the exhaust cross over under the carb that can cause Percolation / driveability problems during extended idling or slow operation - or hard starting.

I installed restricted/blocked off manifold gaskets and removed the riser for these reasons and have had none of the issues since.

Felpro gasket is 1204


Phil