Can this thread compare the engineering differences between Mummerts heads and an original stock set of non posted "G" heads.

I have gleamed some of the differences by reading the existing posts in all of the topics but thought a dedicated post for comparing might be helpfull for quick references.

Also any porting suggestions ? Isnt that terrible

All that work and were just waiting to grind em up

Oldmics

I'm on the East coast now up in Maine. I could be wrong, but I don't think John's new aluminum heads have the bigger intake valves like the "G" heads.

Rono

  Ron Lane,  Meridian, ID

Rono.

  Ron Lane,  Meridian, ID

What is different about the new heads that makes them superior?

Oldmics

Intakes are the same, exhausts are .030 bigger than G heads.  What makes them superior?  John Mummert's expertise.

John - "The Hoosier Hurricane"

I think you will find there has been port flow improvements & combustion chamber efficiency over the cast heads and for me, the dyno figures indicate somethings different.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

       The ports are vastly superior as cast, and they get better with a grinder. If you know how. The combustion chamber design improves the valve shrouding issue, and requires CONSIDERABLY less timing. Means it works better. the heads are less than half the weight of the factory heads and the engine runs cooler, although the water temp will likely be higher!! work on that for a while! Ted picked up 50+ hp with a set.

Frank/Rebop

Bristol, In ( by Elkhart) 

Is there a diagram of the original head ports and then an overlay of Johns improvements to the ports for comparison.

I"m curious what he did to the ports? Moved them in the new castings-changed the pattern?

Oldmics

The intake valve has been moved closer to where the exhaust valve was or away from the edge of the cylinder wall.  To help this along, the exhaust valve was placed closer to its adjoining cylinder wall.  Both the intake and exhaust valves have also been relocated higher in the bore and closer to the intake manifold.  All this makes for better flow numbers before port improvements come into the picture.  The ports themselves have also been reconfigured internally which just adds to the improvement in flow seen from relocating the valves.

The oil drainage in the valve cover area has been greatly improved on the aluminum heads.  Oil drainage is no longer relying solely on the two oil drain holes at each end of the head as the new head design has oil drainage taking place at some of the pushrod holes.

Add to the list of improvements the use of 14mm sparkplugs and redesigned combustion chambers.  The 14mm spark plugs do sit more inboard than the 18mm plugs on the stock heads which at the bare minimum gives additional spark plug wire room around the headers.  The combustion chamber design likes less total timing which makes the combustion more efficient.  Brake specific fuel numbers are lower which points to better fuel economy if the driver can keep a light foot on the throttle.

Lorena, Texas (South of Waco)