71 LS5 Lifter and Cam Failure
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
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From: Denham Springs LA
Great. Repost when you come to a decision as the cams recommended would be for your 8.5 to 1 engine. A compression upgrade, roller cam and a little higher stall convertor would make a huge difference and could still sound and drive like stock. No one would know. Looking at that lifter I would rebuild it. A lot of metal circulating. You can reach in with a file and file the burred edges of the lifters off and pull it right out.
I'll keep the thread updated. Thanks for your help.
Roger
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Joined: Nov 2008
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From: Denham Springs LA
Thanks
Roger
Le Mans Master
Joined: Apr 2011
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From: Hermosa
You can see jagged edge of lifter. Makes me think lifter was loosing contact with flat surface of the cam and when they made contact the edge of the lifter was hitting the cam lobe.
What issues can I look for with the valves to cause a vibration resonance problem?
Last edited by REELAV8R; Oct 26, 2014 at 10:27 AM.
Le Mans Master
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From: RI, Now Franklin/Nashville TN
In my non expert opinion, modern 10-30 has a max of 1000 ppm zinc. These old flat tappets need probably 1400 ppm. In my '67 327/350 I run Delo 400 15w-40 and 4 oz.@Red Line EOS in each oil change. On my '69 350/300, lifters were shot at 90K miles. Most of it lubed with Penzoil 10-40.
I just rebuilt my original 66,000 miles L-82 this spring and had run for years Mobil 1 15W-50-1,200 ppm ZDDP (Mobil 1's Mass market grades of 5W-30, 10W-40, 10W-30 have 800 PPM ZDDP and should NOT be used in flat tappet cammed engines) and the OEM L-82 cam and lifters looked perfect-almost no wear. Running a roller cam in the 355 and will be switching to Mobil 1 Group IV true synthetic 0W-40 (the only Mobil 1 BTW besides Porsche Spec Mobil 1 5W-50 that is a true synthetic in the US) with 1,000 PPM ZDDP.
C3 owners need to mind the oil….
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
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From: Denham Springs LA
To me it kind of looks like the lifter stopped spinning in the bore and just wore in that one spot. In the pic it looks like the right side of the lifter might still be smooth on the edges.
Yes, that's a good description. The lifter easily moves up and down easily, until it hits the jagged edge. It will also rotate easily.
LOL, Based on the experience with my engine I would say ensure that you have the minimum sweep on the valve stem from the rocker regardless of whether that is centered or not and as long as it's not too close to the edge.
Yes, that's a good description. The lifter easily moves up and down easily, until it hits the jagged edge. It will also rotate easily.
LOL, Based on the experience with my engine I would say ensure that you have the minimum sweep on the valve stem from the rocker regardless of whether that is centered or not and as long as it's not too close to the edge.
