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Ted
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Group: Administrators
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Y block Billy (5/14/2010)
Ted, Wouldn't the push rods grow maybe .001" after warm up? we always used the calculation of .003" of growth per foot of material (steel and Iron) for every 100 degrees above ambient temperature for the equipment I set up around the globe. Also I know that the aluminum grows at a much faster rate, the number 1 cause of snowmobile/dirtbike/four wheeler piston failures is the fact that people don't let them warm up before reving them up and the piston grows faster than the cylinder and they get a cold seizure. I don't have handy the exact growth of the aluminum versus the steel for the same temperatures, but as the steel catches up, might it change that figure? I guess I should have clarified growth as ‘net growth’. The net growth is 0.004” regardless of which parts are growing. The aluminum heads could be growing 0.006” while the pushrods are growing 0.001” and the valves themselves are also growing 0.001" which still makes net growth 0.004” when performing a cold versus hot valve lash adjustment. At this point, all that needs to be known is net growth so that when the cold lash is adjusted, hot lash is in the ball park. The difference in lash with aluminum heads from cold to hot is a 0.004” increase.
  Lorena, Texas (South of Waco)
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Hollow Head
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What are the Hp and torque numbers at the same rpm's as tested with G heads? I know the new ones are better at higher rpms but are they waste of money at the lower rpms  ? Can we see some graphs to compare?
 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)
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aussiebill
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Hollow Head (5/15/2010)
What are the Hp and torque numbers at the same rpm's as tested with G heads? I know the new ones are better at higher rpms but are they waste of money at the lower rpms ? Can we see some graphs to compare? Seppo, i initially wondered the same thought, re the Hp @ same RPM and figured the hp or torque nosed over at those rpm,s round the 1st heads results? ted will know for sure. And with the growth rate on the new heads,that amount Ted mentioned is great point, so initial settings can be allowed for. For all my time rebuilding most earlier engines, i,ve allowed .002" cold set and when engine is ran, its nearly spot on for clearance. so this new figure for our new heads is a big help. regards bill.
 AussieBill YYYY Forever Y Block YYYY Down Under, Australia
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Don Woodruff
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This from Teds original Post With the 2” four hole carb spacer, the aluminum heads outperform the iron heads at all rpm ranges. With the 2” tapered carb spacer and below 2800 rpms, the iron heads are only marginally better in torque than the aluminum versions, but after 2800 rpms, the aluminum heads simply run away from the iron versions with the best peak horsepower numbers.
I believe this indicates it is about a wash below 2800 rpm but above 2800 rpm the Al heads are superior with this combination. A guess that with a shorter cam, a smaller carb, the advantage of the Al heads may move a bit lower in the RPM range . Ted is the expert though.
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aussiebill
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Don, thanks for that bit, pretty much what we were thinking. regards bill.
AussieBill YYYY Forever Y Block YYYY Down Under, Australia
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Grizzly
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Last Active: 9 Years Ago
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Impressive!! A 20% increase from the new heads. I, like most, would like to see a comparison chart for the testing done. It's interesting that there is an improvement, even at lower RPM, with a spacer. I would have thought that the standard heads would be giving close to full volumetric efficiency there. The ram effect obviously doing it's thing with a longer inlet. This is what John was talking about getting an improvement over wider range of RPM. With more testing to come we will obviously see and get more information. I would like to see the same test done with heads that have had the ports finished to remove the rough casting surface.
 Grizzly (Aussie Mainline)
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MarkMontereyBay
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I am impressed. Getting ready to pull the 312 from my 57 Bird in a few weeks or so. I will be using a 573 and 94's with Sanderson headers, MSD, etc. Unfortunately, I didn't get the Yblock Magazine this month. I thought my subscription was paid up but I have been living away from the house as it is being remodeled and the mail is a bit chaotic right now. So please, someone post what the expected cost of these new jewels will be.
Thanks,
Mark
57 Black Tbird 312/auto
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Daniel Jessup
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I believe the mag said $2049 if you ordered by the middle of May. I just got my mag two days ago, so I think JM was believing that the magazines would all be in the hands of prospective buyers well before the middle of the month. Unfortunately the USPS got them out a little slowly...
Daniel JessupLancaster, California aka "The Hot Rod Reverend" 
check out the 1955 Ford Fairlane build at www.hotrodreverend.com
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Y block Billy
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Thanks for the clarification Ted, It was the net expansion I was thinking about. Ted/John, What are the flow numbers for the intake/exhaust for these heads out of the box versus the g's and where did the biggest improvements in flow come from? Opening exhaust port? changing angle of lower intake port to valve opening? combustion chamber shape and size ect. ect . ect. ? I will then be curious as to the flow numbers that can be acheived once you guy's start porting them.
 55 Vicky & customline 58 Rack Dump, 55 F350 yard truck, 57 F100 59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?
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Ted
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Group: Administrators
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Hollow Head (5/15/2010)
What are the Hp and torque numbers at the same rpm's as tested with G heads? I know the new ones are better at higher rpms but are they waste of money at the lower rpms ? Can we see some graphs to compare? Here are a pair of graphs. The difference in the two carburetor spacer designs is why you test. A street driver would like the four hole spacer while a racing or ‘spirited driving’ application will prefer the tapered design spacer.
Lorena, Texas (South of Waco)
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