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Old 06-02-2020   #1
Top Toy
 
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Default Valve to Piston Clearance

Has anybody had issues with valves kissing piston tops (high lift cams)? What were the valve to piston clearances? RPM's? Minimum recommended clearances (intake and exhaust)?

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368 LPE/Haibeck, Web cams, Stainless Works headers, B&B Fusion exhaust, 18" Fikse wheels, Alcon brakes, lowered. 491 SAE RWHP.
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Old 06-05-2020   #2
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Default Re: Valve to Piston Clearance

Yes. But was an over rev situation. I design around .060 intake, .100 exhaust. If the driver is sketchy, now I?ll increase that. [emoji5]


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Old 06-05-2020   #3
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Default Re: Valve to Piston Clearance

Should have clarified that the whole system must be accounted for.... cam accel/decel rates must be matched to the spring force, with at least 20% margin of safety.


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Old 06-06-2020   #4
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Default Re: Valve to Piston Clearance

Quote:
Originally Posted by tpepmeie View Post
Yes. But was an over rev situation. I design around .060 intake, .100 exhaust. If the driver is sketchy, now I?ll increase that. [emoji5]


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Thanks Todd! Any idea what the RPM's were when the valves touched? And what the clearance was prior to that? Any other contributing factors? I ran with 0.084" exhaust clearance on my '93 motor and never had an issue. I try to stay as close to factory ramp rates as possible.

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368 LPE/Haibeck, Web cams, Stainless Works headers, B&B Fusion exhaust, 18" Fikse wheels, Alcon brakes, lowered. 491 SAE RWHP.
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