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3 angle valve job vs. 5 angle valve job


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#1 jtmxrider

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Posted 23 September 2008 - 08:53 PM

can anyone explain to me why some ppl tell me that 5 angle valve jobs are more for track only cars, and why they wouldnt be very street worthy or reliable?
ive heard that if its goin to b drivin on the street more than the track then i need to go with a 3 angle....

#2 SiberianFirestorm

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Posted 24 September 2008 - 12:09 AM

For drag racing, it is worth the money. For a daily driver or a more street car, it is not worth it.

Matt
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#3 Me Too

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Posted 26 September 2008 - 12:22 AM

It's the width of the seat that determines which is better for street or strip. Obviously for the street and valve sealing longevity you want the widest seat possible, so a three angle is considered the best. However, with a 5 angle job, the air transistions more smoothly around the valve head and that makes a bit more horsepower, but the valve sealing over the long haul isn't as good.

A wider seat transfers heat from the valve head to the head better. GM uses a single cut, the head is 45 degrees and the valve is 46 degrees, a three angle valve job will add horsepower over this arrangement and will give acceptable life, but the GM single cut will last longer. Honda uses a three angle on all of its engines, and gets maybe 250,000 miles out of a valve job. With a high quality valve, such as a Feria 6000 series, or Manley Pro-Flow, it doesn't seem to make any difference how many angles are cut.

I'd go with a three angle for the street and using stock valves.




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