1212

Does anyone know why there is a stainless steel block gasket in between the riser and manifold on a 454 330 '82? I am wondering if this is necessary and if I would get any benefit from taking it out. I am replacing a leaky gasket and saw these in there and was wondering if someone put them in by mistake. Any help would be appreciated.

dereknkathy

gasket blocks off all 4 holes? you have closed cooling. antifreeze in motor-manifolds and raw water in the risers. the reason tyose motors still exist is the closed cooling. 30 years of florida salt woulda rotted out 2 sets of motors by now. your gasket leak is probably the face of the riser getting pitted.

1212

Yes the gasket blocks all 4 side holes and two front an rear holes. i thought the same thing, that that was supposed to be for closed cooling but I actually have a raw water setup. Instead of the water coming through those holes, there is a hose that goes into the side of the riser. i put new risers and manifolds on a few years ago and everything has been working fine but each time I take a riser off for some reason or another, I wonder why those blocking gaskets are on there.

dereknkathy

so you have a hose from top of man to bottom of riser? then you could remove block-offs...stock merc exhaust? 82 was around the time they went from logs to center-dumps. which manifolds do you have? or are they the old 420 exhausts with big 6-bolt riser bolt pattern?

1212

they are logs. yep hose from man to riser. 4 bolt riser. i think i may have figured it out. it is possible that those are blocked in order to create more pressure (volume) of water flow to the transmission, ps, and oil coolers. i checked the service manual and it shows that they are supposed to be blocked with the merctans. the borg warner setup uses a different block gasket where only 2 holes are blocked.