im in the process of a HG job and i would like to compare the OE gasket to a FEL-PRO gasket , seems that FEL-PRO only punches two holes on the coolant jackets around the cyllinder walls , this looks like it highly restricts coolant flow because the coolant jacket is way bigger than the two tiny holes that FEL-PRO stamps on the heas gasket . same applies to a pair of FEL-PRO intake manifold gaskets , the rear coolant ports were not punched out and instead only had one tiny little hole . BTW im talking about the MLS gaskets .

 

Here is my original head gasket before going to the Fel-Pro.

 

thanks . so looks like FEL-PRO MLS are just like OE gaskets , the coolant ports themselves are way bigger than the two little holes that are punched out at the ten o' clock and three o' clock positions " as outlined in the picture " . Wouldn't thishinder coolant flow ? , is there a reason behind this ? would making the holes a little bigger increase the chance of gasket blowout ? or does this have to do with GM's theory that hotter engine temps are better for emissions ?

 

I don't know the answer. I do remember thinking that the new Fel Pros looked a bit odd in regards to cooling port holes. But it's been years since the head gasket repair, that I can't remember specifics of it.

It may reduce hot spotting of the heads. But I'm purely guessing.

 

probably , it would be nice to get some more coolant flow around the cyllinders . if i ported the holes for the water jackets on the gasket . Think theywould blow out ?

 

I work at Cummins and we do the same thing. We use those holes to adjust cooling flow. If you open those holes up, it will improve cooling flow there, but will cause a hot spot elsewhere. Those holes are used to balance the flow throughout the engine.

The rear crossover port is not on all of the manifolds. My HSR doesn't have a rear crossover. I'm not sure if my stock TPI did or not.

 

thanks for the info ,i guess i wont be touching the holes then .