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| Advantage of flat tapped cam over roller cam. (Page 1/3) |
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La fiera
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DEC 20, 07:39 PM
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Notorio
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DEC 22, 01:58 PM
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Is there a Cliff's Notes version available? 
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La fiera
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DEC 22, 09:58 PM
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| quote | Originally posted by Notorio:
Is there a Cliff's Notes version available? |
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Who is Cliff?!!!
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Gall757
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DEC 22, 10:18 PM
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https://www.cliffsnotes.com/
It's what you turn to when you don't have time to read the whole book, and the exam is tomorrow.....  [This message has been edited by Gall757 (edited 12-22-2020).]
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La fiera
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DEC 23, 12:21 PM
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| quote | Originally posted by Gall757:
https://www.cliffsnotes.com/
It's what you turn to when you don't have time to read the whole book, and the exam is tomorrow.....
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Oh I see!!! I wish I had that when I went to school! 
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Patrick
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DEC 23, 01:39 PM
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| quote | Originally posted by La fiera:
I wish I had that when I went to school!
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You must be really old, as Cliffs Notes have been around since 1958. 
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ericjon262
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DEC 23, 01:43 PM
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so yes, a flat tappet can actuate the valve faster, the major downside though, is the durability of the cam, flat tappets, if not broken in correctly, and blessed with high zinc oils, will end up having "lobes" with 720 degrees of closed duration with a quickness. for most street engines, I don't think the ramp rate of a flat tappet will really come into play, as most street cams don't have enough duration for it to matter.
me personally, I'll stick with rollers, until something more interesting comes along, I don't like the idea of wiping a lobe. ------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
cognita semper
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Patrick
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DEC 23, 02:11 PM
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| quote | Originally posted by ericjon262:
...and blessed with high zinc oils
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Yes, I believe the relative unavailability of that (and/or the use of it with a cat) is the major issue with having flat tappets in this day and age.[This message has been edited by Patrick (edited 12-23-2020).]
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pmbrunelle
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DEC 23, 04:40 PM
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| quote | Originally posted by Patrick:
Yes, I believe the relative unavailability of that (and/or the use of it with a cat) is the major issue with having flat tappets in this day and age.
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I don't think that automakers avoid flat tappets because the oil has less zinc. If automakers requested zinc-loaded oil, oil companies (and the API) would produce it.
I submit that "the major issue" with flat tappets today isn't with oil availability, but these two requirements from the EPA:
1. Car should last 100k miles with Joe Average doing no maintenance, but still meet emissions requirements. So you need to avoid catalyst poisons.
2. Fuel economy needs to be good. Flat tappet has too much friction.
These two requirements lead to moving to roller cams and reduced zinc in the oil.
From a classic-car owner perspective, I found that the local auto parts store 5 minutes away has Liqui-Moly 10W-40 with MOS2 as recommended by La Fiera for flat tappets.
It's $65 for a 5L jug. With a 5000 km oil change interval, that means I change the oil once or twice a year on my Fiero. Maybe less from now on, since working from home seems to be an irreversible change, so I have less commuting to do.
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Patrick
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DEC 23, 05:47 PM
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| quote | Originally posted by pmbrunelle:
If automakers requested zinc-loaded oil, oil companies (and the API) would produce it.
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My understanding is that zinc kills cats, and I'm not referring to the furry kind.
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