LS cam/lifter failure

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fastblackracing
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LS cam/lifter failure

Post by fastblackracing »

My son and myself help out a few of our friends with their cars from time to time and this one Is a 98 Trans-Am with a 408 inch LS.

We had just got done Installing the nittrous set up a few weeks ago and they went out and started making some nitrous hits to get the system set up and timing A/F ratios where they need to be.

On the way back the engine starts with a squeeking noise so they end up stopping at a friends shop and pull the fresh filter and cut it open finding metal in it and flat bed the car back to my house.

Upon tear down we find #2 intake lifter and lobe destroyed, and on further inspection after cleaning everything up I find a bunch more wrong with this cam.

Engine is a 408, 12.8-1, with nice heads & intake on it, made 545 rwhp and is just a great driving Hot little street ride.....has 2000 miles since this engine was put together.

The cam came from Btr, but was ground by comp ~3 years ago? I notice what looks to be some almost burnt looking spots on the cam, a few marks that look like dents in the lobes and a finish on the lobes that looks like corrugated cardboard or steps if you will, pronounced enough i can feel them with my finger nail especially where the opening ramp transitions to the lobe nose.

A local shop put this engine together as I did not have time, and must not have looked at the cam very well....it looks like a pos to me with my 58 YO eyes!

A replacement cam was ordered and I guess BTR is grinding their own cams now? The lobe finish is night and day different between the 2 cams with the replacement looking like a proper finish to me.

Lifters were the GM lifters everyone uses for these engines.

My thinking is the step lookjng finish was vibrating the lifters pretty hood and creating some extreme pressure on the lobes and rollers.

Thoughts on this? I was not able to get a good pic of the corrugated lobe finish but hopefully that makes sense.

CC poor quality?
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1980RS
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Re: LS cam/lifter failure

Post by 1980RS »

fastblackracing wrote: Sun Aug 16, 2020 9:46 pm My son and myself help out a few of our friends with their cars from time to time and this one Is a 98 Trans-Am with a 408 inch LS.

We had just got done Installing the nittrous set up a few weeks ago and they went out and started making some nitrous hits to get the system set up and timing A/F ratios where they need to be.

On the way back the engine starts with a squeeking noise so they end up stopping at a friends shop and pull the fresh filter and cut it open finding metal in it and flat bed the car back to my house.

Upon tear down we find #2 intake lifter and lobe destroyed, and on further inspection after cleaning everything up I find a bunch more wrong with this cam.

Engine is a 408, 12.8-1, with nice heads & intake on it, made 545 rwhp and is just a great driving Hot little street ride.....has 2000 miles since this engine was put together.

The cam came from Btr, but was ground by comp ~3 years ago? I notice what looks to be some almost burnt looking spots on the cam, a few marks that look like dents in the lobes and a finish on the lobes that looks like corrugated cardboard or steps if you will, pronounced enough i can feel them with my finger nail especially where the opening ramp transitions to the lobe nose.

A local shop put this engine together as I did not have time, and must not have looked at the cam very well....it looks like a pos to me with my 58 YO eyes!

A replacement cam was ordered and I guess BTR is grinding their own cams now? The lobe finish is night and day different between the 2 cams with the replacement looking like a proper finish to me.

Lifters were the GM lifters everyone uses for these engines.

My thinking is the step lookjng finish was vibrating the lifters pretty hood and creating some extreme pressure on the lobes and rollers.

Thoughts on this? I was not able to get a good pic of the corrugated lobe finish but hopefully that makes sense.

CC poor quality?
I stopped buying any cams that are made by comp years ago after several failures.
bigmike
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Re: LS cam/lifter failure

Post by bigmike »

Were the valve lifter guides OEM GM or aftermarket? Were the lifters OEM GM LS7 or aftermarket?
I stopped buying any cams that are made by comp years ago after several failures.
Me to. Same with with their lifters.
cab0154
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Re: LS cam/lifter failure

Post by cab0154 »

the stock blocks are well known for core shift causing limited oil flow, and taking out lifters and cams. so it may not have been the fault of the cam
"Anyone who thinks the low RPM engine will be faster just does not have as much experience as the rest of us" -The late, great Joe Sherman.
fastblackracing
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Re: LS cam/lifter failure

Post by fastblackracing »

bigmike wrote: Mon Aug 17, 2020 12:54 am Were the valve lifter guides OEM GM or aftermarket? Were the lifters OEM GM LS7 or aftermarket?
I stopped buying any cams that are made by comp years ago after several failures.
Me to. Same with with their lifters.
Lifters were GM ls7 New with this cam, and valve lifter guides? I assume you are meaning valve guides? Valve guides are what came in the trick flow heads on this engine...Iron guides in this set of heads. Curious about the valve guide thought and core shift comment.

I will try to get pics of of the lobe corrugation posted tonight.

This Block, crank and rods ran 50k miles on its last build up.
fastblackracing
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Re: LS cam/lifter failure

Post by fastblackracing »

Pics of the can lobe corrugation and engine compartment.
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Monza355
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Re: LS cam/lifter failure

Post by Monza355 »

fastblackracing wrote: Mon Aug 17, 2020 4:39 pm Pics of the can lobe corrugation and engine compartment.
Last camshaft I bought from Lunati looked like this as well. (Cam was for gen 1 sbc) I did not like it at all. And I am pretty sure if that cam would’ve made it into a engine. The lifters wouldn’t have lasted long !
bigmike
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Re: LS cam/lifter failure

Post by bigmike »

Lifters were GM ls7 New with this cam, and valve lifter guides? I assume you are meaning valve guides?
No.. valve lifter guides or AKA valve lifter trays.

You might check out these two youtube videos on LS.

https://www.youtube.com/watch?v=8CzhCryAjLM

https://www.youtube.com/watch?v=cIq2xxu79NA
fastblackracing
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Re: LS cam/lifter failure

Post by fastblackracing »

Monza355 wrote: Mon Aug 17, 2020 4:56 pm
fastblackracing wrote: Mon Aug 17, 2020 4:39 pm Pics of the can lobe corrugation and engine compartment.
Last camshaft I bought from Lunati looked like this as well. (Cam was for gen 1 sbc) I did not like it at all. And I am pretty sure if that cam would’ve made it into a engine. The lifters wouldn’t have lasted long !
Thanks, that is pretty much my thoughts, it just did not work out time wise for us to do the engine build this time so the kid had a local performance oriented shop do the build and I am amazed that they did not see this and question it.
fastblackracing
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Re: LS cam/lifter failure

Post by fastblackracing »

bigmike wrote: Mon Aug 17, 2020 5:34 pm
Lifters were GM ls7 New with this cam, and valve lifter guides? I assume you are meaning valve guides?
No.. valve lifter guides or AKA valve lifter trays.

You might check out these two youtube videos on LS.

https://www.youtube.com/watch?v=8CzhCryAjLM

https://www.youtube.com/watch?v=cIq2xxu79NA
Of course the plastic trays, thanks for that.
I will check those vids out.
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Re: LS cam/lifter failure

Post by A_VAS »

poor quality grind from Comp, pretty much the root cause.

8620 cores can be sourced from CamMotion...And they will usually be polished and smooth looking !
too lazy to make power w/o boost
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