Reusing old cam?

Discussion of the 331-354-392 HEMIs.

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NE57
Posts: 192
Joined: Fri Mar 27, 2009 12:54 pm

Reusing old cam?

Post by NE57 »

What do I look for on an old cam to see whether it's still servicable? I measured duration and lift on a few lobes and its at least in the ballpark of what I'd like(I think)(230ish at .050 @ the lobe, .298 lift at the lobe) cam maker did not respond to an ID request, but before I get too involved I need to know if the cam is in good shape or not. The lifter bottoms look good, very little wear marks that I can see but I would replace all the lifters in any case. The lobes are mostly black with very narrow white shiny areas from lifter contact. If the cam checks out service-wise I'll check timing details more closely.

Also, when doing a 050 check, is that measured at the lobe or at the valve? I measured at both .050 and .033 at the lobe figuring if it should be checked at the valve the 033 would be the equivalent once you allowed for rocker ratio. Flawed thinking?

Guidance much appreciated, thanks.
dan miller
Posts: 86
Joined: Wed Dec 27, 2006 5:05 am

Re: Reusing old cam?

Post by dan miller »

I know not much about cams, but it's my understanding that if the lifters are all convex (just put the base of one lifter against the side of the other and hold it up to a light source), and the wear patterns on the lobes all appear similar, it's acceptable to reuse the cam and lifters. However, they need to remain in the same block that they came out of, and each lifter needs to ride on the same lobe that it came off of. Any mixing, and there is a very probable flat cam in your future. I've also heard that new lifters on an old cam are also an invitation for disaster.

Reground cams and lifters are relatively inexpensive.

Danny
NE57
Posts: 192
Joined: Fri Mar 27, 2009 12:54 pm

Re: Reusing old cam?

Post by NE57 »

Unfortunately this engine was a basket case and all the lifters were stuffed in a bag so can't use them. I know about wrong lifter/lobe pairings but I hadn't heard about new lifters/old cam being a problem. I take it then that even having the lifters refaced wouldn't help?
krooser
Posts: 58
Joined: Sun Sep 01, 2002 8:21 pm

Re: Reusing old cam?

Post by krooser »

Those lifters can be resurfaced for just a few dollars. There are several cam grinders that can do that for you.
China...Great Food...Crappy Tools
392heminut
Posts: 488
Joined: Sat Nov 30, 2002 2:16 pm

Re: Reusing old cam?

Post by 392heminut »

NE57 wrote: I know about wrong lifter/lobe pairings but I hadn't heard about new lifters/old cam being a problem. I take it then that even having the lifters refaced wouldn't help?
I've never had a problem using new lifters with a used cam, but haven't done it in the last several years. The new engine oils have been reformulated and have a LOT less zinc, which is what helps lube the cam lobes and lifters, especially during break-in. I would think you would be okay as long as you use a good cam assembly lube and a good zinc additive in the oil for break-in, probably something from one of the cam manufacturers.
Owner of the Poor Man's Hemi Cuda
phil
Posts: 31
Joined: Sun Dec 28, 2003 6:07 am
Location: AUSTRALIA

Re: Reusing old cam?

Post by phil »

for the price of a new cam , go for a new one at least you know it will be new
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