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Supreme Being
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| Now please tell me about those roller rockers? Ratios availiable and where to obtain them. Oldmics
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Supreme Being
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Ted:
I noticed on the top picture with the old style rockers with jamb nuts it has different stands than stock.
Does the new head require these different rocker stands?
Does the new heads require a special length of push rod or will one of the three lengths of '55 and later y-block push rods Ford used fit.
marv
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Supreme Being
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Oldmics (5/31/2010)
Gentlemen 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 On the contrary removing the "as cast" finish is know to improve flow. A linished finish is desirable not smooth or polished finish. I'm interested where in the RPM range this linished finish will provide an increase. It could be that the next step could turn them into racing heads and better in the WOT, high RPM applications. As these head are released I'm sure that there will be tuning tips and HP will increase accordingly. As people try different things in there own application. Porting is the obvious next step and of course there is different levels of porting. I think John has put more material in the port walls to accommodate racers and additional porting. I'm guessing that when John Sits down and ports the heads for the racer trial the flow bench will reveal some secrets.
 Grizzly (Aussie Mainline)
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Oldmics (6/1/2010)
Now please tell me about those roller rockers? Ratios availiable and where to obtain them. The pictured rockers are 1.6:1 ratio and available from Dove Manufacturing. The Harland Sharp 1.6:1 rockers are similar except bronze bushed for the shafts and although the HS rockers have not been tested on the aluminum heads, they are expected to fit just like the Dove rockers as far as pushrod alignment goes. For the aluminum heads, I’ve found that a different combination of left, right, and zero pushrod offset rockers are required versus the combination used on the iron heads. I have a set of 1.6:1 Rocker Arm Specialist rockers here (on loan from Gary) and those look to be installable on the aluminum heads but some additional offset rockers will need to be ordered to make up a full pair of rocker arm assemblies for both heads.
  Lorena, Texas (South of Waco)
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marvh (6/1/2010)
Ted:
I noticed on the top picture with the old style rockers with jamb nuts it has different stands than stock.
Does the new head require these different rocker stands?The pictured stands are supplied with the aluminum heads as the original stands will no longer bolt up. The relocated valves necessitated new stands with a wider bolt spacing but these new stands still work with factory shafts and rockers. The bolt sizes holding the pedestals to the heads have been increased from 5/16-18 to 3/8-16.
marvh (6/1/2010)
Does the new heads require a special length of push rod or will one of the three lengths of '55 and later y-block push rods Ford used fit.Going from the iron to the aluminum heads and keeping the 1.54:1 rockers in place required a longer pushrod. The iron headed engine had the 7.970” pushrods while 8.105” pushrods were used with the aluminum heads. When switching to the 1.6:1 rockers on the aluminum heads, a set of 7.935” long pushrods were installed.
Lorena, Texas (South of Waco)
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Supreme Being
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I could be mistaken, but I believe there's a correction needed on the inquiry about original valve sizes. 1957 head intakes were 1.925" in Dia. not 1.94". Replacement Stainless valves are 1.94". Correct?
Paul
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Supreme Being
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| Can you tell us what venders are offering the longer push rods to accomidate the al heads? I assume (you know what happens when you assume  ) Mummert is selling the longer push rods? Oldmics
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Supreme Being
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Oldmics (6/2/2010)
Can you tell us what venders are offering the longer push rods to accomidate the al heads? I assume (you know what happens when you assume ) Mummert is selling the longer push rods? Oldmics Why not keep things in perspective! just ask john, i think you will find that after developing these heads, he, john has the accompanying parts to make it all work!!:
 AussieBill YYYY Forever Y Block YYYY Down Under, Australia
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Supreme Being
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| The correct length pushrod for the aluminum heads is the same as the 1954-55 and 60-64 Y-Blocks so they are readily available. I have 300 on the shelf just in case. Valves were moved closer to the intake manifold. Rocker shafts also needed to be moved to retain the same distance from the valve stem to the rocker shaft so existing rockers could be used. Intake valves were moved toward the exhaust valves. Exhaust valves were moved away from the intake valves. Current valve spacing is 1.815". This limits total valve diameter of intake and exhaust valve to 3.52". Spark plug has been moved closer to the exhaust valve while Ford put the spark plug on the exact centerline of the cylinder. Spark plugs are now 14mm instead of 18mm. As you might guess the ports are not as large as they could be. We needed to make a streetable head for engines as small as 298 cu in ( .030 over 292). Intake valves are 1.94" as sold. We have already done some porting and testing with 1.98" intake for Ted's EMC engine. We have tested a lower intake port @ 274CFM and 255CFM with a ported intake installed. This pencils out to 500HP+
http://ford-y-block.com 20 miles east of San Diego, 20 miles north of Mexico 
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Supreme Being
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I note that the new heads have virtually square exhaust ports at the exit. Ford ports had an angle in the inside corner at exit (just on the end ports if I recall without looking at a head) & I recall reading that this was because flow dropped there if the port was opened up there to much. Comments?
Paul
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