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Offset intake valve
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BFB
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PostPosted: Sat Jul 19, 2025 9:50 am    Post subject: Offset intake valve Reply with quote

ok, so ive been reading on some head & valve stuff again recently and came across a couple articles about the big hp v8 guys that run 2 valve / cylinder heads moving the intake valve over so its more centered in the bore / chamber. This obviously allows a bigger intake along with unshrouding but the size of the exhaust valve has to be sacrificed.
It got me to thinking and wondering why it’s not done in the vw community? Or maybe it is, i dont know? Can’t say ive ever seen anything on it before, hence me bringing it up.
Obviously opening up the heads for larger cylinders more or less centralizes the intake valve more and unshrouds it. But why not move the exhaust valve over and make room for larger intake? Considering the design of vw engines youd think itd wouldnt be any big deal for the PR tubes to shift over some and rockers could be shimmed over too , to a certain extent anyhow.
I could see it being too much work vs return if modifying heads but i wouldnt think itd be that big of a deal for a head designer / manufacturer so make ?
Maybe they already do this if nothing else to a small degree to get more room between the valves?
I dunno? Thoughts?
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Brian_e Premium Member
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PostPosted: Sat Jul 19, 2025 10:46 am    Post subject: Re: Offset intake valve Reply with quote

Been done forever in the Vw race stuff.

The new 063 heads have the exhausts moved over .050”.

Brian
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Alstrup
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PostPosted: Sat Jul 19, 2025 12:07 pm    Post subject: Re: Offset intake valve Reply with quote

Yes.
In smaller bore race stuff I have moved the intake over by 0,100" and tilted it 2 degrees more. Thats partly contributing to get 160 cfm @ 0,530" through a 37 mm valve in a 77 mm bore. This fall I will begin on a new version of such a head. My goal is to find 5-10 cfm more with the same port volume. Possible (?) Time will tell.
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dangerous
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PostPosted: Yesterday 3:36 pm    Post subject: Re: Offset intake valve Reply with quote

Hi Alstrup, can you share some pictures of the changed angle? I assume you went 11.5 degrees? Where is the offset, in the chamber or top of the guide? I guess you want the tip of the valve still in line with the others.
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Alstrup
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PostPosted: Today 9:18 am    Post subject: Re: Offset intake valve Reply with quote

Sorry. no pics. They were lost during a reboot of a German Website a couple of years back, and I had no back up. But the intakes were moved 2,5 mm sideways toward the exhaust and then tiled 2 degrees away from the spark plug, so 2 degrees less actually. This served 3 purposes. 1. getting the valve away from the spark plug. Getting more "free" room on the fast (plug) side. 3 A straighter shot from the manifold flange downwards.
This exersise positioned the outer diameter of the larger valve in the same position in relation to the cylinder wall as a std 33 mm valve.
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chrisflstf
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PostPosted: Today 9:26 am    Post subject: Re: Offset intake valve Reply with quote

Is this done on a head before its machined to locate the valve guide and seat location?
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