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PostPosted: Sun Nov 07, 2021 6:05 am 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
Posts: 1176
Location: N. Ga.
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Greg, that practice is actually very common in NASCAR and many high level Comp Eliminator and Pro Stock drag classes that start out with blank cylinder head castings and other classes that require production cylinder head castings like Super Stock. For a slant, the better solution is to shift the valve location by machining the bore for the guide in the cylinder head, and then making an oversized OD guide to insert in the head. If you make an eccentric valve guide to offset the valve, you risk compounding error when you install the guide by shifting it any number of infinite resting places, kinda like an eccentric cam bushing. Boring the guide hole in the head is going to be much simpler and consistent valve to valve than an eccentric bushing will be.

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PostPosted: Sun Nov 07, 2021 7:25 am 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
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Location: N. Ga.
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Charrlie_S wrote:
For a newly designed head the numbers you asked for are irrelevent, unless the valves are in the stock location. If you design the head, lets say for canted valves, the size could be different. My opinion, a "bolt on" head, would basically be just a stock head in aluminum, and a waist of time and money. If spending the effort, for a alloy head, it should be an improvement over the stock head, in terms of flow.

Correct Charrlie, it would largely be a waste of time. All inline forums(Chevy, Ford and Chrysler) have many threads over many years about this same topic. The main failure point is that not much thought is put into the making of the rest of the components to make it work, like intake manifold, exhaust manifold or header, valve cover, rocker arms and shafts, camshafts and a way to drive them if they are overhead style. The head is really only a small part of the bigger picture...

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PostPosted: Thu Dec 02, 2021 6:37 am 
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EFI Slant 6

Joined: Sat Mar 19, 2016 7:25 pm
Posts: 256
Location: SW PA
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Moving the valves is done by milling the cast flush then offset boring the guide hole & then finish sizing for a common replacement guide. Usually .500" bore. The chance for finding porosity/water is always there, & goes up the more You offset. This will require FluidWeld or an epoxy to prevent seepage. I'm prepping to move some on a set of Olds heads soon.


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PostPosted: Thu Dec 02, 2021 6:57 am 
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EFI Slant 6

Joined: Sat Mar 19, 2016 7:25 pm
Posts: 256
Location: SW PA
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One of the perks of going to a smaller stem besides the usual benefits is it can buy You some room if don't mind turning the OD of a std. guide down.


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PostPosted: Fri Dec 03, 2021 6:51 am 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
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Location: N. Ga.
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Killer6, pm sent....

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