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| differing camshaft core diameters https://slantsix.org/forum/viewtopic.php?t=64278 |
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| Author: | justa170 [ Wed Dec 04, 2019 2:08 pm ] |
| Post subject: | differing camshaft core diameters |
I have one cam out of a 170ci motor and another from a 198. The core diameter of the 170 cam is much greater than that of the 198 cam. The 170 was built in 1961; I think the 198 is from 1970-ish. I haven't stumbled into any references to this difference in dimensions, so I was surprised to see it. Did Chrysler put the slant six cam on a diet for cost savings? |
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| Author: | Joshie225 [ Wed Dec 04, 2019 2:19 pm ] |
| Post subject: | Re: differing camshaft core diameters |
Everything costs money including iron. The cam did slim down after the first few years of production as did the crankshaft. |
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| Author: | jcc [ Thu Dec 05, 2019 10:53 am ] |
| Post subject: | Re: differing camshaft core diameters |
The large D 170 cam if same or better metal sounds like a good candidate if a cam regrind is in the future and the grinder can maintain as much as possible of the original base circle, correct? |
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| Author: | drgonzo [ Thu Dec 05, 2019 11:06 am ] |
| Post subject: | Re: differing camshaft core diameters |
Quote: The large D 170 cam if same or better metal sounds like a good candidate if a cam regrind is in the future and the grinder can maintain as much as possible of the original base circle, correct?
I would think more material would be very beneficial when altering the lobe separation angle along with an aggressive lobe profile.
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| Author: | Killer6 [ Thu Dec 05, 2019 1:38 pm ] |
| Post subject: | Re: differing camshaft core diameters |
My memory is a little faded after ~30 yrs., but the first /6 build I used a Crane unit with lift in the mid .400's, it was based on a large diameter core. I know the switch-over was discussed previously, but I'm fairly certain the lobe size/profile was the same, until the actual specs were changed. I seem to recall there wasn't a lot of meat between the base circle and the core dia. which presents a problem. If You're going for mega lift, the core may have to be ground recessed larger than the lifter dia. to prevent the edges from making very unfortunate contact.That would mean cutting a fillet-radius type groove on either side of the lobe's base circle...................... |
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| Author: | Joshie225 [ Thu Dec 05, 2019 3:02 pm ] |
| Post subject: | Re: differing camshaft core diameters |
Quote: The large D 170 cam if same or better metal sounds like a good candidate if a cam regrind is in the future and the grinder can maintain as much as possible of the original base circle, correct?
The base circle of the cam lobes is the same on the thick cams and the skinnier ones. The base circle gets very close to the diameter of the shaft of the thick cores so there is actually less room to reduce the base circle without undercutting the shaft and doing that is costly.
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| Author: | jcc [ Fri Dec 06, 2019 4:59 am ] |
| Post subject: | Re: differing camshaft core diameters |
Quote: Quote: The large D 170 cam if same or better metal sounds like a good candidate if a cam regrind is in the future and the grinder can maintain as much as possible of the original base circle, correct?
The base circle of the cam lobes is the same on the thick cams and the skinnier ones. The base circle gets very close to the diameter of the shaft of the thick cores so there is actually less room to reduce the base circle without undercutting the shaft and doing that is costly.
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| Author: | justa170 [ Fri Dec 06, 2019 12:06 pm ] |
| Post subject: | Re: differing camshaft core diameters |
Quote: I seem to recall there wasn't a lot of meat between the base circle and the core dia. Yup. That's what I see on my 170 cam. My first reaction was "Is there something wrong with this thing?" 
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