Smog heads vs Regular heads.
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Racer
Joined: Apr 2001
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From: Golden Colo.
Smog heads vs Regular heads.
What is the difference between the two. I realize you need a port for the EGR valve to receive exchust from the emmision head but is there anything else that is different.
Race Director
Joined: Aug 2000
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Re: Smog heads vs Regular heads. (82zoom)
It is a term applied to cylinder heads made after 1974. When unleaded fuel came into use, the valve seats needed to be hardened, because of the lack of lead in the gasoline. Also, "smog heads have a heat crossover and the EGR hookup. Most of the "smog heads" were older designs, cheap castings, prone to cracking because of the higher temps the engines were being forced to operate. Even though the L82 had 2.02 intake valve, it really isn't a good head. The internal configuration of the head, plus the chamber size and shape, precluded any hi-performance application.
That doesn't mean you can't make these heads perform. However, by the time you port, polish, bowl blend, etc., you may as well purchase a set of aftermarket heads and already be way ahead from the get-go. If you are into originality, keep the "smog head" and trick it out to the max. You will see a performance gain, but not as much compared to any aftermarket head. JMHO.
Fellow members, feel free to correct any misinformation I may have inadvertently wrote. :D
[Modified by sd pacecar, 7:53 PM 9/5/2002]
That doesn't mean you can't make these heads perform. However, by the time you port, polish, bowl blend, etc., you may as well purchase a set of aftermarket heads and already be way ahead from the get-go. If you are into originality, keep the "smog head" and trick it out to the max. You will see a performance gain, but not as much compared to any aftermarket head. JMHO.
Fellow members, feel free to correct any misinformation I may have inadvertently wrote. :D
[Modified by sd pacecar, 7:53 PM 9/5/2002]
Race Director
Joined: Aug 2000
Posts: 12,975
Likes: 22
Re: Smog heads vs Regular heads. (82zoom)
No! Many of the aftermarket manufacturers certify their heads 50-state legal. AFR, Edelbrock, World Products, Dart are just a few of many that sell smog compliant heads. Do a search on cylinder heads and you will find a lot of info in the archives. It all depends on how much money you have to spend.
