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04-22-2018, 09:50 PM | #11 | |
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Location: Glendale, Arizona
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Re: Flat tappet lifters
Quote:
The main root cause for a lifter to loft or jump the camshaft nose is inadequate open valve spring pressure. Dwell nose camshaft lobe designs have less propensity to loft. Nevertheless, in a nutshell, the key is proper selection of valve springs to prevent lifter lofting. |
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04-22-2018, 11:40 PM | #12 | |
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Join Date: Apr 2018
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Re: Flat tappet lifters
Quote:
That is the answer I thought I was going to get, doesn't seem right at all to have an inherent loft at those engine speeds and the given operating times. It seems that our past Schubeck lifter failure was the result of swiping the ceramic puck off rather than a valve float/loft issue. Looking at the failed Schubeck lifter it seems the failure mode of the puck has been due to a shear load rather than an impact load. Correct spring pressures and lash settings have always been constantly maintained with approx. 250-300# seated and around 700 over the nose with PAC springs. The remainder of the valve train has no shortcuts, with titanium valves and retainers used, jesel high end rockers and correct pushrod sizing. Do you have a preferred camshaft supplier for using the recommended DLC lifters with? Again thanks for the advice. |
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04-23-2018, 09:42 AM | #13 | |
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Re: Flat tappet lifters
Quote:
Yes, your forensic assessment on what took place with the Schubeck lifter is correct. Check your private messages. |
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