what are possible causes of cams breaking

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Sweet P
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what are possible causes of cams breaking

Post by Sweet P »

SBC and BBC billet cams that break towards the rear of the cam, but in front of the gear.

What could be causing this?
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Re: what are possible causes of cams breaking

Post by Frankshaft »

Crappy cores. Comp Cams?
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Re: what are possible causes of cams breaking

Post by cgarb »

Sounds like they need to increase the radius in the corner of the relief cuts.
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Re: what are possible causes of cams breaking

Post by PackardV8 »

1. High volume/high pressure oil pump
2. High valve spring pressures
3. High intensity lobe profiles
4. High lift lobe profile on a small diameter cam core.
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Re: what are possible causes of cams breaking

Post by Sweet P »

PackardV8 wrote: Tue Sep 11, 2018 3:39 pm 1. High volume/high pressure oil pump
2. High valve spring pressures
3. High intensity lobe profiles
4. High lift lobe profile on a small diameter cam core.
Yes, all of these except only 100 oil psi
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Re: what are possible causes of cams breaking

Post by CamKing »

Sweet P wrote: Tue Sep 11, 2018 1:34 pm What could be causing this?
There are multiple reasons, you can have a cam break, but the most common problem, is the induction hardened cores, some companies use.
A proper core, has the lobes and journals hardened, and the material between the lobes and journals(the barrel), left soft, so it's less brittle.
This allows the cam to flex and twist, without breaking.
On the mass-produced, induction hardened cams, the coils that heat treat the lobes, aren't always exactly over the lobes, and sometimes harden the area between the lobes. This is what causes them to crack and break between the lobes. The reason most SBC's and BBC's break at the back, is because the largest span between to journals is between the rear 2 journals.
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Re: what are possible causes of cams breaking

Post by steve316 »

why do you need 100 psi oil pressure?
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Re: what are possible causes of cams breaking

Post by Frankshaft »

Curious on the brand that were breaking.
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Re: what are possible causes of cams breaking

Post by CamKing »

Frankshaft wrote: Wed Sep 12, 2018 9:32 am Curious on the brand that were breaking.
Most of the ones I've seen come from the core manufacturer, Engine Power Components. They are Comp's biggest supplier, but sell to almost all cam companies.
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Re: what are possible causes of cams breaking

Post by swampbuggy »

How fast are you spinning this engine ? what are you driving the camshaft with chain, belt, gears ?
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Re: what are possible causes of cams breaking

Post by Frankshaft »

CamKing wrote: Wed Sep 12, 2018 10:05 am
Frankshaft wrote: Wed Sep 12, 2018 9:32 am Curious on the brand that were breaking.
Most of the ones I've seen come from the core manufacturer, Engine Power Components. They are Comp's biggest supplier, but sell to almost all cam companies.
That's what I was getting at. The few I have seen break, were comps. They were small base circle sbc cams though, with a fair bit of spring, and running a fair bit of rpm.
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Re: what are possible causes of cams breaking

Post by stealth »

I’ve seen oil pump driveshafts forced down with distributor clamp twist, cam gears worn off off and pump gears ruined from lack of clearance.

Could be your breaking cams.? ...is pump shaft jammed tight with distributor clamp?
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Re: what are possible causes of cams breaking

Post by blwilliams »

Broke two Comp cams on a blown BBC with a dry sump. No oil pump driven off the distributor. In fact engine uses a front drive distributor.
Both cams broke just past the last lobe in the rear.
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