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#11 |
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Join Date: Nov 2016
Location: Indianola Washington
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It is curious how NHRA tech dept approves a replacement cylinder head when the runner volumes are considerable larger than their own stated specification. Its been said replacement heads are worth 15-20 HP on a SBC combination. The replacement heads with the HP penalty, seem to produce the same ETs.
Steve Teeter. STK. 6380 |
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#12 | |
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Join Date: Dec 2002
Location: Lower Dakota territory
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- OEM head: 165 cc intake/65 cc exhaust - NHRA specs on Edelbrock heads (5 hp penalty) : 172 cc intake/65 cc exhaust - Edelbrock's specs on these heads: 185 cc intake/65 cc exhaust When I asked an NHRA Technical official about this, I was told (paraphrasing) that if anyone showed up in Stock with the accepted Edelbrock heads, they would be illegal if they had the 185 cc intake ports. And if the intake ports measured 172 cc, they wouldn't pass because they would have to have been illegally modified (welding) to get down to 172 cc.
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"That'll never work....." |
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#14 |
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Join Date: Dec 2009
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So !! a set of closed chamber iron heads is more expensive than a new set of aluminum heads ?? Whats next ?? the cam is hard to grind with the stock lift ??
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#15 |
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Join Date: Jan 2006
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This replacement head deal is way out of hand, there are plenty of good stock casting for SBC and oval port and square port BBC, you just have to get your wallet out and there really not that expensive when your building a competitive stock or super stock Engine, And no you can't buy them from jegs or summit.
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#16 |
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Join Date: Oct 2004
Location: Hickory, Ky
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If anyone needs some 906 cores I have 40 to 50 heads.
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#17 |
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Join Date: Feb 2008
Location: Georgetown, Indiana (close to Louisville, KY)
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Yep
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#18 |
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Hi All,
The reason that most of the replacement heads are only legal in Super Stock is that they have to be modified by filling in the runners to the correct cc's. You can't weld or use epoxy in the runners of a Stock head. Combustion chamber volume can also be adjusted in SS and not Stock. The replacement head just supplies a blank sheet of paper to start with and can be made legal by machining. Whatever you use it must conform to the NHRA Blueprint Specs including valve size. Bob
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Bob Mulry 7516 STK A & M Motorsports |
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#19 |
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Larry:
I can match your fifty 906's and raise you 20 more. About 200 Mopar heads on shelves in my shop.....Some for 40 years or more!
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John Irving 741 Stock 741 Super Stock |
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#20 | |
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Join Date: May 2006
Location: Murfreesboro TN
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![]() Quote:
That's hilarious. How many heads and engines do you build? And just how good are you at welding cast iron heads for Super Stock?
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Alan Roehrich 212A G/S |
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