Exhaust crossover restrictor plate 4.3 OMC cobra.

[42 Clyde]

My head gasket kit came with restrictor plates for the exhaust crossover in the intake manifold. Does anyone know what they do? What benefit they might provide? Would i want to use them?

 

[Scott Danforth]

there are 7 generations of 4.3's with 7 variations of induction

what are you working on? be very specific to the year of the motor (not the boat) and what intake and carb are on it.

only the early 4.3's with a divorced choke need any exhaust running thru the manifold. the exhaust running thru the manifold is a throw-back to old divorced chokes. you dont want much running thru the manifold, because warm intake makes less power.

however only if you have a divorced choke do you need any.

if you have an electric choke you do not need any exhaust running thru the manifold, and on later manifolds, there is no cross-over.

 

[Lou C]

When I took my 1988 apart, the restrictor plates were actually part of the intake gaskets and I installed the new Fel Pro gaskets with the supplied restrictor plates. It limits the amount of hot exhaust gas passing through the bottom of the intake manifold, just enough to make the choke open but not so much as to cause fuel boiling in the carb bowl on a hot day.

 

[42 Clyde]

The block is a 1986 or 87. Bored .020 over. Flat tapit hydraulic lifters. Two barrel Rochester carburetor with a choke that looks like it is heated through the crossover. I dont know much about the carb or intake but they worked well on the cracked motor i took them off of and they both have the same numbers cast into them. The gasket i took off didnt have the restrictors but the new gasket has add on restrictors.