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Valvestems on the inlets are worn out!

General engine tech -- Drag Racing to Circle Track

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Caprimaniac
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Valvestems on the inlets are worn out!

Post by Caprimaniac » Fri Nov 29, 2019 6:07 am

Yeah; and I figured out. Slack on inlet valves in their guides... Put them in the tight ex valves/guides, and there was still slack.
Machine shop measured and gave me the convict yesterday, and New valves has to be bought. No biggie.

What Puzzles me is; after 12 years? Car used 10- 20 days a year? But then; on track and strip....+ going to and back from them events.....

I was 100% sure the GUIDES were up to be replaced, but the valves went first?

Last 10 years these heads have run shaft rockers. And RPM was all under 8000rpm.. (pomise!). Set the limiter to 7500.

However; a few- 3-4? years before that, I ran regular rockers. And I took it to 8000 more than once. Did see fretting/marks on the rocker studs.

Did those early years take the valves out? And is it normal for valve(stems) to go Ahead of the guides?

Edelbrock Vic Jr heads. SS valves, bronze guides. Used as "Out of the Box".
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Re: Valvestems on the inlets are worn out!

Post by mag2555 » Fri Nov 29, 2019 6:43 am

I don't think the valve's in Edelbrock heads have the needed long life chrome stems, or they do have chrome plating it may just be a thin flash coating.

Anyway once valve stems get to show .001" ware you must understand that it makes for that .001" times 3.14 in extra clearance, so at that point your valves are really rocking around and both the valves and guides will ware at a much faster rate at that point!

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Re: Valvestems on the inlets are worn out!

Post by turbo camino » Fri Nov 29, 2019 9:23 am

I saw that a lot on late-'80s Chevy iron heads, mostly 305s it seemed like, though maybe because we did more of those than others. Tons of slop, throw in a set of new valves and everything is back to normal. We just assumed the factory was using lower quality valves during that era as nothing else would really explain it.

Feed it some good quality chrome stem valves and don't worry about it.
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Re: Valvestems on the inlets are worn out!

Post by PRH » Fri Nov 29, 2019 10:37 am

I have serviced/freshened many Edelbrock heads over the years.
My experience has been that if the heads were run “ootb”, there is a very good chance the intake valve stems will show significant wear.
The typical guide clearance for their heads ootb is about .0005 on the intakes.
This doesn’t seem to be enough for proper lubrication with those valves in those guides.

I’ve also gotten quite a few sets back for freshening that I had sold originally...... and when I sell them new I set the guide clearance about .0005 bigger, so......0010 int/.0015ex.
The ones I’ve prepped have basically no measurable wear on the stems when I get them back.
As always...... ymmv.

Also, the stem diameter of the Ede valves is about .0005 smaller than most typical replacement valves(.3405 vs .3410).
So if you got something like Ferrea or Manley valves instead of Ede valves, you’d have just about “0” clearance on the intakes.
Somewhat handy with a die grinder.

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Re: Valvestems on the inlets are worn out!

Post by Caprimaniac » Fri Nov 29, 2019 11:45 am

PRH wrote:
Fri Nov 29, 2019 10:37 am
I have serviced/freshened many Edelbrock heads over the years.
My experience has been that if the heads were run “ootb”, there is a very good chance the intake valve stems will show significant wear.
The typical guide clearance for their heads ootb is about .0005 on the intakes.
This doesn’t seem to be enough for proper lubrication with those valves in those guides.

I’ve also gotten quite a few sets back for freshening that I had sold originally...... and when I sell them new I set the guide clearance about .0005 bigger, so......0010 int/.0015ex.
The ones I’ve prepped have basically no measurable wear on the stems when I get them back.
As always...... ymmv.

Also, the stem diameter of the Ede valves is about .0005 smaller than most typical replacement valves(.3405 vs .3410).
So if you got something like Ferrea or Manley valves instead of Ede valves, you’d have just about “0” clearance on the intakes.
That's a great advice right there.... And as said above; maybe not the best chrome on the Edel stuff??

I'm a bit out to lunch here right now, as the parts are at the machinist and stupid didn't measure LENGTH of valves before they went there.

Edelbrock say 5.060" length. Hopefully correct.

If that is true; how about 5.110" length Milodon 2.05""Megaflow competition"? If Method of measuring is same With the two: +0.05" lenght. Probably keep the height of my rockerstand and have enough in the adjusters?

Move Down to 2.02" diameter, and Manley has a "Race series" 5.04" length. However- and I suspect a missprint here: 146.99$ each(? - probably a set of 8). Part no 11796-8.
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Re: Valvestems on the inlets are worn out!

Post by mag2555 » Fri Nov 29, 2019 11:56 am

If you got that 5.060" size off of the Edelbrock site then your good!

Unless you need greater installed height for a different spring then do not add weight by going to a longer valve,even if it's only .050".

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Re: Valvestems on the inlets are worn out!

Post by PRH » Fri Nov 29, 2019 12:15 pm

Ferrea likely has something in the 5.060 length......it’s +.150.
maybe not the best chrome on the Edel stuff??
Perhaps...... but at .0010 clearance they seem to hold up fine.
Somewhat handy with a die grinder.

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Re: Valvestems on the inlets are worn out!

Post by midnightbluS10 » Fri Nov 29, 2019 12:25 pm

Going by past experience, I suspect the "-8" in the part # represents a set of 8. Considering the price, that seems logical to me.


Edited to add: that would be correct. 11796-8 is a set of 8 valves. The single valve is listed as 11796-1 for $19.99, as seen below


https://www.barnettperformance.com/6015 ... age=lookup
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Re: Valvestems on the inlets are worn out!

Post by Caprimaniac » Fri Nov 29, 2019 3:45 pm

Yes; figured out it's a set of 8. Or so Jegs say, at least.

Keeping spring height as is. Seats is getting a thouch-up, so they'll sink in some, too.

I'll go with some off-the summit-shelf this time, not Ferrea. Just a streeter anyways. So; will try Manley.

Although…. as you say; the edel's have hold up well, really. And they're very cheap, I'd say, at around 115 a set. But the 50 bucks extra for the Manleys will be worth it if the stems are thick enough to avoid new guides; or if they maybe hold up even better…

Thanks for input, lot's of help as I need to purchase these ASAP for delivery in a week or so.
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Re: Valvestems on the inlets are worn out!

Post by PRH » Fri Nov 29, 2019 4:01 pm

The guides are usually surprisingly good even when the stems are worn .001-.002.

Hone up to the proper clearance and they’re good to go.
Somewhat handy with a die grinder.

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