Bad Valve Stems?

[SRS_Chris]

I came across something a little unusual for the second time today. The valve stems on all 8 intake valves were worn beyond recognition. I didn't measure, but think .030" wear! The middle of the stem was worn away. This is only the second time I have ever seen this. The first time both intake and exhaust valves were bad. This time only the intakes (exhaust were good). I measured the guides and to my surprise they are all straight with 0.0014" clearance and about 0.0002" taper at the chamber side (both intake and exhaust)(measured with a Sunnen P300). In both instances they were +0.100" small block Chevy valves in Edelbrock heads. Did Edelbrock receive a bad run of valves in the past? What could have caused this?

[Tom68]

I came across something a little unusual for the second time today. The valve stems on all 8 intake valves were worn beyond recognition. I didn't measure, but think .030" wear! The middle of the stem was worn away. This is only the second time I have ever seen this. The first time both intake and exhaust valves were bad. This time only the intakes (exhaust were good). I measured the guides and to my surprise they are all straight with 0.0014" clearance and about 0.0002" taper at the chamber side (both intake and exhaust)(measured with a Sunnen P300). In both instances they were +0.100" small block Chevy valves in Edelbrock heads. Did Edelbrock receive a bad run of valves in the past? What could have caused this?

Sounds like the stem material was wrong for the guides ??

[SRS_Chris]

In both instances they are the valves that came in the heads from Edelbrock. Stainless valves with bronze guides. Beyond that, I'm not sure what specific stainless steel or bronze materials Edelbrock would use.

[bigmike]

That sounds like a heat treatment issue to me.

[mag2555]

Sounds like a issue of little to none of the needed chrome plating on the stems.

[bigmike]

Not sure I've ever seen chrome plating on the stems of aftermarket Stainless valves. They rely on proper material and heat treatment.

[n2omike]

Are you sure the valves are not STRETCHING... which would thin them out in the middle?

[mag2555]

4 of the 7 series of SS valves that Manley makes have chrome plated stems, but it does not seem like you can say the same for Ferrea valves which is odd to me!

[PRH]

I have run into this situation a few times with E heads.
I’ve only seen it happen on heads that were run “ootb”.
One set of SBC heads, a few sets of BBM heads.

Heads that I have prepped/sold, when they come back in for freshening have essentially no wear on the valves.

My summation was/is, the guide clearance was too tight(I open them up a few tenths), and wonder about how well Ede cleans out the guides after sizing.
That might allow honing grit to get embedded in the guides........ and wear out the stems.

I don’t feel the tight clearances and white lithium grease assy lube helps in getting oil flowing into the guides early on.

Like the OP, when I’ve come across this worn stem condition, the guides still measure good.

[BOOT]

Not sure I've ever seen chrome plating on the stems of aftermarket Stainless valves. They rely on proper material and heat treatment.

I thought it was pretty standard to chrome plate the stems on most valves, although it's not very thick.

chrome plate stem thickness.jpg

[BOOT]

4 of the 7 series of SS valves that Manley makes have chrome plated stems, but it does not seem like you can say the same for Ferrea valves which is odd to me!

Ferrea chrome plates the stems for 5000 & 6000 series and may others, i just googled it quick.

https://www.ferrea.com/5000-series-hi-p ... alves/c165

https://www.ferrea.com/6000-series-comp ... alves/c166

[BOOT]

All Chrome plated stems

https://www.milodon.com/valves/street-s ... valves.php

https://www.compcams.com/sportsman-stai ... 001-1.html

http://www.pbm-erson.com/Catalog/PBM/Va ... _V/PBM1001

For the eddy ones scroll down it's in the details, not saying all are, just these from a quick search

https://www.edelbrock.com/intake-valves ... -9366.html

https://www.edelbrock.com/intake-valves ... 93775.html

[SRS_Chris]

I have run into this situation a few times with E heads.
I’ve only seen it happen on heads that were run “ootb”.
One set of SBC heads, a few sets of BBM heads.

Heads that I have prepped/sold, when they come back in for freshening have essentially no wear on the valves.

My summation was/is, the guide clearance was too tight(I open them up a few tenths), and wonder about how well Ede cleans out the guides after sizing.
That might allow honing grit to get embedded in the guides........ and wear out the stems.

I don’t feel the tight clearances and white lithium grease assy lube helps in getting oil flowing into the guides early on.

Like the OP, when I’ve come across this worn stem condition, the guides still measure good.

Interesting, but why only the intake and not exhaust valves in my most recent case? The first time I saw this happen it was both. In any case, I've ordered a new set of Manley intake valves and will be honing the guides to create some cross hatch. Hopefully this helps with oil retention and stem lubrication.

[Baprace]

SRS_Chris, is it possible the heads were assembled with 8mm .0315 LS valves ?

[Caprimaniac]

FYI- my edel Vic jr’s 11/32 stems, after 10 years of abuse, 2-3 with stud rockers, after that a shaft setup, all the valves had stems worn out, and in need of replacement.
All except one guide were good to go.
One or another need to go- guide or stem- the time it takes have to do with seats, geometry, material, etc