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Author Topic:   head ?
racingrandy
Dirt Roller

Total posts: 6
posted August 11, 2005 07:40 PM  
What exactly is the difference between 305 HO and plain old 305 heads? Is it just valve size

btennant
Dirt Full Roller

Total posts: 28
posted August 11, 2005 08:43 PM  
Oh cantrare the 305 H.O. heads actually have the same size valves as regular 80s 305 heads the difference is in the shape and volume of the combustion chambers also if you pull the valves out of the H.O. head you will notice that the intake runner is machined about 3/4 of an inch into the pocket wich helps promote airflow. Its like a factory port and polish job. And it just sounds cool to say

Raz_900
Dirt Forum Champ
Total posts: 635
posted August 11, 2005 09:43 PM  
HO heads are 1.84"/1.5" valves. Alot of 'normal' 305 heads were 1.72"/1.45". The chamber's are 56-58cc were the others are 64cc I believe. They're good for about a point of compression or so plus the extra airflow.

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