Aussie Heads valve swap
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Joined: Dec 1999
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From: New Orleans United States
Aussie Heads valve swap
I've heard about swapping the 4V valves into the 2V open chamber heads to get better flow without killing port veolicity when swapping to a 4V head all together. Can the 4V valves be squeezed into the 2V Aussie closed chamber heads with the same results?
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Joined: Aug 2001
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Aussie Heads valve swap
Yes they can. Although Scott at Cam Research talked me out of the larger intake valve. He says it screews up the flow characteristics and dosn't improve things. But I did get the larger exhaust valve.
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Joined: Jan 2002
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Aussie Heads valve swap
There is a lot of shrouding of the 4v intake valve when it is fitted to closed chamber 2v heads, even moreso than with 4v quench heads due to a smaller chamber. Hoever, if you are willing to drop a little compression, this situtaion can be rectified.
Junior User
Joined: Jan 2002
Posts: 79
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From: Chelsea United States
Aussie Heads valve swap
Or, another option that has worked for me: Have the existing seats cut at 30-degrees. (from the standard 45-degree seats) You will need a set of 4v valves cut down accordingly to match the new 30-degree seat, but don't have the machinist open the seat any larger in diameter, just cut for 30-degree seat, with a 45-degree under the seat, then 60 degree blended into bowl. Your valve size, after cut down for new seat, should be approx 2.10 or so. Not much bigger than factory valve so shrouding is not dramatically increased, but I gaurantee low lift flow increases..........Just one of my little secrets...... - Don, New York
Tuned
Joined: Jun 2001
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Aussie Heads valve swap
>Or, another option that has worked for me: Have the existing
>seats cut at 30-degrees. (from the standard 45-degree seats)
>You will need a set of 4v valves cut down accordingly to
>match the new 30-degree seat, but don't have the machinist
>open the seat any larger in diameter, just cut for 30-degree
>seat, with a 45-degree under the seat, then 60 degree
>blended into bowl. Your valve size, after cut down for new
>seat, should be approx 2.10 or so. Not much bigger than
>factory valve so shrouding is not dramatically increased,
>but I gaurantee low lift flow increases..........Just one of
>my little secrets...... - Don, New York
Is that what they call a 3-angle valve job?
>seats cut at 30-degrees. (from the standard 45-degree seats)
>You will need a set of 4v valves cut down accordingly to
>match the new 30-degree seat, but don't have the machinist
>open the seat any larger in diameter, just cut for 30-degree
>seat, with a 45-degree under the seat, then 60 degree
>blended into bowl. Your valve size, after cut down for new
>seat, should be approx 2.10 or so. Not much bigger than
>factory valve so shrouding is not dramatically increased,
>but I gaurantee low lift flow increases..........Just one of
>my little secrets...... - Don, New York
Is that what they call a 3-angle valve job?
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Joined: Dec 2001
Posts: 31
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From: Sydney Australia
Aussie Heads valve swap
Ive also been told that fitting a 4V inlet is no good,as causes too much shrouding.
Have a good look at these charts,Waldens web site, http://www.waldens.com/waldens/351heads.htm
Especially the specs on the Ported aussie heads, they outflow even 4v heads both stock 2v and 2v with 4v valves.
Its a shame they havent got the specs on aussie heads with 4v valves though. Maybesomeone knows where we could get this info from, it would be great to know 4 sure which is the best Clevo head combo.
bfn
Have a good look at these charts,Waldens web site, http://www.waldens.com/waldens/351heads.htm
Especially the specs on the Ported aussie heads, they outflow even 4v heads both stock 2v and 2v with 4v valves.
Its a shame they havent got the specs on aussie heads with 4v valves though. Maybesomeone knows where we could get this info from, it would be great to know 4 sure which is the best Clevo head combo.
bfn
Junior User
Joined: Jan 2002
Posts: 79
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From: Chelsea United States
Aussie Heads valve swap
bbtkd,
No, not exactly. It IS a 3-angle valve job I am refering to, however, most 3-angle valve jobs consist of a 30-45-60 degree cut (3 angles) and use the 45-degree margin for the valve seat. I use a wider 30-degree margin as the valve seat, cutting the valves (which are cut 45-degrees) to a 30-degree angle/seat/face. This results in more actual flow area for an equal amount of lift as compared to a valve using the standard 45-degree seats. Understand so far? If not, ask, I will be happy to explain further and in greater detail....
- Don, New York
No, not exactly. It IS a 3-angle valve job I am refering to, however, most 3-angle valve jobs consist of a 30-45-60 degree cut (3 angles) and use the 45-degree margin for the valve seat. I use a wider 30-degree margin as the valve seat, cutting the valves (which are cut 45-degrees) to a 30-degree angle/seat/face. This results in more actual flow area for an equal amount of lift as compared to a valve using the standard 45-degree seats. Understand so far? If not, ask, I will be happy to explain further and in greater detail....
- Don, New York
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Joined: Dec 1999
Posts: 582
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From: New Orleans United States
Aussie Heads valve swap
Thanks for all the info. I'm gonna buy a set off of ebay next week after payday and then start looking at what i want to do with them. I think just port matching the intake and exhaust and getting the larger cut down valves on the 30 degree seat should be a nice jump. This engine is bored .060 over but I doubt this will affect the CR so much that i would need more than pump gas to run it. I'll keep ya up to date on what happens.
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Joined: Sep 2001
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From: Jax FL
Aussie Heads valve swap
out at the powerhead site, the have the flow figures for aussie 2v heads with 4v valves. when you unshraound the aussie heads for the valves, the chamber volume is usually increased to around 62cc. so you go from 58 to 62 head size to get the better flow. you can contact powerheads for more detail.
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Joined: Dec 1999
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From: New Orleans United States
Aussie Heads valve swap
The heads are on the way. I'm sending my money order out tomorrow, and should have them early next week. They're coming dissasembled but with the valves, springs, and retainers in the box. They're also coming with literature to rebuild them to however I want along with a contact list of shops knowledgable with bulding these heads. All in all, with freight included, its coming to $395.00.
Was this a reasonable price?
Was this a reasonable price?