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OOPS!!

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woody

Posts: 485

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Mon Apr 18, 2011 5:43 pm

OOPS!!

Last year I bought a new set of S&S/FHP heads. Since my cylinders are quite heavily relieved, I went for the high compression option thinking that it would make up for the loss from the relieving. I was assembling the valves in the cylinders yesterday and decided to put a head on and check how much valve travel I have. Not enough :cry:.

I am thinking of using a cutter to make the radius of the valve pocket in the head smaller to give more room for the valve. Does anyone see any problems with this? Any other suggestions? I would consider selling these and buying new with different compression if anyone was interested. Trades OK also.
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Frankenstein

User avatar

Posts: 1546

Joined: Thu Jun 27, 2002 12:01 am

Location: Interlaken, NY USA

Post Mon Apr 18, 2011 7:28 pm

Re: OOPS!!

The KR racing manual suggested brazing a cutting tool to an old valve inserting in guide, and then turning the valve to gain clearance in heads that lacked a deep enough pocket for valve clearance. Sounds like a back yard fix, but can't be all that bad for them to put it in the racer manual.
DD
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woody

Posts: 485

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Tue Apr 19, 2011 7:26 pm

Re: OOPS!!

Dr.,

Thanks for the reply. I am aware of the remedy you describe. It is a common fix for valve to piston contact in OHV car engines. I have a fixture that I can bolt the head to and tilt it in a mill to match the valve angle. My concern is that reducing the valve pocked radius (sharper corner) will effect flow. Am I overthinking this?
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RUBONE

Posts: 380

Joined: Fri Nov 30, 2007 7:24 pm

Post Tue Apr 19, 2011 9:13 pm

Re: OOPS!!

My concern is that reducing the valve pocked radius (sharper corner) will effect flow. Am I overthinking this?

Just grind a radius on the tool! :roll:
Robbie
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woody

Posts: 485

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Wed Apr 20, 2011 5:14 pm

Re: OOPS!!

Robbie, thanks for the reply. I am apparently not being clear as to the what I need to know and I don't want to be an jerk about it, so maybe some background is in order. I have been a toolmaker/tool designer for nearly 30 years and have a fairly complete machine shop in my garage. I also have access to CNC if I need it. My problem is not the tool to use or its design. I just want to know if making the radius smaller in the valve pocket of the head will interfere with flow.
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don

Posts: 552

Joined: Fri Oct 01, 1999 12:01 am

Location: Spokane WA USA

Post Wed Apr 20, 2011 5:40 pm

Re: OOPS!!

Leonard Andres used clear heads and smoke flowed his motors to find this answer.
don
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woody

Posts: 485

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Wed Apr 20, 2011 6:51 pm

Re: OOPS!!

Don,

Do you have any idea what his results were?
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don

Posts: 552

Joined: Fri Oct 01, 1999 12:01 am

Location: Spokane WA USA

Post Wed Apr 20, 2011 7:46 pm

Re: OOPS!!

No, but seeing is believing to optimize flow.
Given the "Heavy relieving" that you state, You may not find an easy answer from anyone.
don
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jib

Posts: 570

Joined: Sat Dec 10, 2005 3:36 pm

Location: devon,england

Post Thu Apr 21, 2011 4:32 am

Re: OOPS!!

why not , get the desired clearance above the valve heads 120 abd 80 if i remember right and then reradius the pockets, thats what i did with the 45 heads after milling then to 6 spec and installing kh cams. regards jib
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years
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MOLDTHREAD

Posts: 118

Joined: Fri May 04, 2007 5:46 am

Location: BRANFORD, CT

Post Thu Apr 21, 2011 6:29 am

Re: OOPS!!

Hi Woody,

I have some old HD instructions on modifing older KR heads to take the latest dome piston.
Valve to head clearance MINIMUM.
Intke = .120"
Exhaust = .080"
Corner radius 1/8"
This radius actually forms a undercut in the head by 1/16 max on the backside of the valve to prevent shrouding.
Good luck,
Bruce
http://www.enfieldracing.com
Bruce Argetsinger
AHRMA Dirt Track # 67J
www.enfieldracing.com
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woody

Posts: 485

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Thu Apr 21, 2011 6:19 pm

Re: OOPS!!

Thanks, Bruce. That is the information I was looking for. It looks like I have a lot of cutting to do. I am using oversize valves and they hit the heads before full lift. If anyone buys the S&S heads, do not get the high compression.

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