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Iron Butt, SS2000
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Discussion Starter · #1 ·
Hi Everybody, I have been wondering... Why did the MoCo decide on a twin cam design? The first time I ever heard of a Twin Cam 88 I had visions of a dual overhead cam. When I saw that they were still a pushrod design I was excited that "the look" was traditional HD but I was also let down hoping for DOHC. Anyway, does anyone know what the logic was? :hmmm:
 

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My understanding is the twin cam design allows better valve train geometry while maintaining a "traditional Harley" pushrod engine.
 

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Hellbound Train
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Overhead cams would need much longer cam chains and we all know that's a bad thing, don't we guys,,,,don't we guys,,,,guys ????
 

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Premium octane member
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csoday said:
Overhead cams would need much longer cam chains and we all know that's a bad thing, don't we guys,,,,don't we guys,,,,guys ????
oh but imagine a gear drive sytem for it............:yikes:
 

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Iron Butt, SS2000
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Discussion Starter · #7 ·
Sifted through all 11 pages

WoW. Thanks Springer, your knowledge, passion & tenacity is admirable.
 

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csoday said:
Overhead cams would need much longer cam chains and we all know that's a bad thing, don't we guys,,,,don't we guys,,,,guys ????
hehe, maybe like the early jags.
 

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Highly Seasoned Rider!
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I think it had a lot to do with correcting the poor geometry of the single cam design as mentioned above. The idle on the TC is noticeably smoother than the earlier single-cammers. That's likely one reason. Besides, two of most anything is better than one, isn't it?

:)
 

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killer sperm
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When Porsche designed the engine they took Harley to school on machining the engine parts. They are now done in a fraction of the steps it took for the Evo's, dramaticly reducing the opporunitys for errors.
 

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For the answer to your question who better to ask than Donny Peterson of Heavy-Duty Cycles. Donnie was provided an exclusive look at the new TC before the it was made available to public. In the following article (as located on his company's website), Donnie gives an overview of the new design including why two cams.

http://www.heavydutycycles.com/heaven.htm
 

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I really liked my EVO,bought it new in 1985,it made all right sounds. I will withhold judgment on the TC until mine comes in and I get a chance to ride it some. This will be my first rubber mount HD,although I have rode an FXRD before.
 

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johnny_red said:
My understanding is the twin cam design allows better valve train geometry while maintaining a "traditional Harley" pushrod engine.
+1

Look at the angle of the pushrods on an EVO. Valve train geometry is much better with the twin cam design.

Tim
 
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