drk421

I had a pretty bad camshaft gear failure. The camshaft gear was totally grind down, but the distributor gear was pretty much fine, with just a little wear. I was told by Comp that a melonized distributor steel gear would be fine, which is what I had. I do have a high volume ( not high pressure) oil pump which was recommended for a 408 stroker. Comp said that a high volume oil pump was probably the culprit, but I find that hard to believe because I know lots of guys running those but with Crane cams.

It only took about 50-75 miles before it went bad, and I had to pull the oil pan and remove all the metal pieces.

Anyway, does anyone else have any experience with a cam gear going bad? And what else might cause it?

fakesnakes

Do you have a roller cam? Steel distributor gears eat iron cam gears for lunch in less than 100 miles. Sounds like a classic mismatch between the cam (iron) and distributor (steel) gears.

drk421

The Comp Cam (part # 35-560-8) was a roller cam.

Well, I'm going with a Crane Cam this time, who recommended their steel gear. I've heard much better things about Crane than Comp.

Starfury

wow, you killed a distributor gear on a roller cam? I've never heard of that. Roller cams are hardened steel, so usually you end up killing the distributor gear, not the cam gear.

I have no complaints about Comp Cams, and haven't heard many serious problems with them outside of yours.

Get the Crane setup while you can. They're in the process of liquidating their stock.

drk421

^^^
Yeah, that's what the guy at Comp said.
He was really surprised that the Cam gear was destroyed, usually the distributor gear goes.

I'm very tempted to put a stock oil pump in just to be sure it doesn't happen again.

Starfury

I would, while you have it apart. Throw in an ARP hardened oil pump driveshaft while you're at it.

Why are you running a high volume pump?

drk421

The guy at the engine shop recommended it for a (351w) 408 stroker with a blower (8 pounds of boost).

When the engine was running, it would run at about 75 PSI when cold and 50PSI when hot. I was told that the pressure might drop too low with a standard pump when the engine got hot.

Starfury

When you have a worn engine with lots of bearing clearance and need to pump more fluid at lower rpm's to take up the extra space. Not necessary on a new motor, assuming it's built properly.

67mustang302

It's not the pump. And yes, with boosted apps you are better off with a HV pump. The reason is they generate more oil pressure starting at a lower rpm, if boost comes on low it'll load the bottom end up, you need enough oil pressure to keep the crank and rods floated, otherwise you can hammer out your bearings. I'm running a HV pump with a roller cam, steel cam and steel dizzy gear, not a single problem.

There's a few possible culrpits. 1 is that the cam thrust or dizzy thrust may not have been correct, so the gears were loading on the wrong spot and getting too hot, and it just happened to be the cam gear that took the brunt. Another possibility is that oil flow from the heads out of the front drain holes wasn't enough to cool the gears, and again, it got hot and it just happened to be the cam gear that went. The 3rd possibility is that the cam gear may not have been heat treated properly during manufacturing, or(and you'll have to check on this) it could be a roller cam with an iron gear, setup for roller cam swaps on older engines.

Starfury

Erm, missed the 'blower' part of that. Oops.