I had just finished installing my new aluminum heads (bare Speedmasters ported by Dwayne, valves, seals and spring cups supplied by him, reused my Comp 953 springs, keepers and retainers from my iron heads with 1370 gentle street miles.
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The first section below is reposted from a thread I started on Questions & Answers, asking about valve lash setting (EOIC vs. TDC).

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A couple of days ago, as the engine stopped I heard an interesting metallic "clinking" (sounded like something hitting the valley pan, or possibly the #2 header tube that runs very near the shock tower). It wasn't there at idle (or higher), and I couldn't find anything and it didn't come back. So I drove it to two cruise-ins (about 10 miles each, one-way) on Fri and Sat, no problems or noises, ran it up to 5200 a couple of times.

Today I fired it to warm up for lash setting and cold vs. hot check, and once again at almost-stalling engine rpm the clanking came back, louder than before! So I shut it down and decided to disassemble as necessary until I found it. I clearanced the header tube, and pulled the valve covers. No loose pushrods or broken rocker arms... ok. I started running the valves in firing order from #1, and when I got to #4 exhaust I could see that one keeper half on the exhaust valve wasn't properly seated and had popped up a little Oh poop (paraphrasing), I said, that clinking may have been the valve meeting the piston

A close look at the rest of the valvetrain showed the same problem on #7 intake. Naturally, one on each head, so if those valves are bent, both heads have to come off - in other words, the entire head R&R has to be done over again.

Before you ask, yes, I did check piston-to-valve clearance and the intake was .114" and exhaust much larger. So I'm somewhat at a loss as to why these keepers came loose - I was careful to check all 16 when assembling the seals and springs on the bench, to make sure they were seated.

So I ordered another set of 10 degree locks at a minimum. Maybe I'll get lucky and those two valves and guides will be intact and I won't have to pull the heads for repair, but I'm not holding my breath.
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Now today I removed the rocker shafts, and the failed keepers on #4 and #7 came out. The displaced half actually fractured into two pieces in my fingers. Both of those valves feel as though they were seating properly. BUT as I lifted the left shaft off, I could see that #3 intake wasn't even attached to its keeper any more! That keeper had a rocker arm pad-shaped wear mark on the top, further confirming that it had failed to hold up the valve. Luckily, my new valve seals helped prevent it from falling into the cylinder. That would have been fun.

And worst of all, with a straightedge along all the tips, it would not come up closer than about .080 to the perfect straight line of the others, and of course the cylinder would not hold air, all coming out the carb. So that one, at least, is bent. Explains the clank noises all right.


So at least the left head has to come off... and #3 intake valve replaced. Hope there is no damage to the KB280 pistons' valve reliefs or tops.

The big question, of course, is WHY did this happen? :thinking:

I felt sure that the keepers were properly seated when I assembled the springs on the bench, because I know what happens when a valve falls into
the cylinder.

I have not over-revved the engine.

My calculations showed that there should be plenty of p/v clearance. There was with the same short block and cam on my iron heads! Once I repair the damage I think I'll clay it for a direct measurement.

A couple of snaps of the carnage so far:


I'm going to replace all 32 keeper halves after finding this third injured valve.

Valve spring pressure/condition is the first thing I’d check
Edit-> any witness marks on the keepers from the rocker arm?

I love the edit button.

Sorry to see this on your fresh heads.

Was the installed height and coil bind checked on the springs before assembly?

These springs and retainers came right off the iron heads... I think I checked at least one but maybe I forgot!
The springs themselves are suitable for this cam and I didn't install any shims (just the spring cups) so I doubt they are too low but. I will be checking everything before putting the head back on!

Hard to tell by looking at pics on my phone......... but it kinda looks like keepers for 3/8” valve stems being used on valves with 11/32” stems.

I broke a keeper just like that when installing the valve spring. The keeper slipped out of the groove just as I released the spring compressor. It got wedged between the valve stem and the retainer and snapped it in half.
Not sure what the answer is to this problem, but while you are ordering parts, order a set of ARP 300-8332 nuts. It's a pack of 10, 3/8"-24, 12-point, reduced wrenching (7/16" socket) flange headed nuts. They cost less than $15 and they will make your life a lot easier when installing the rocker shafts.

Brian

If I was a betting man I would say you are right, all stock iron mopar heads have 3/8 valves, and almost all aftermarket have 11/32 valve stems. I have had issues with keepers breaking if you snap them too hard while assembling, but it looks like the keepers just don't fit right.

The new heads use valves with 11/32 stems.

I just remembered I was putting some heads together a few months ago.
I opened a sealed bag of 611-16(11/32) locks for that job.

11 pieces of what was in the bag were 612’s(3/8).

Gotta check everything.

3/8” locks on 11/32”” stems will unfortunately fit well enough for you to assemble the heads....... if you’re not paying attention.
But it won’t end well.

1st pic- 3/8 locks on 11/32 valve

2nd pic- 11/32 locks on 11/32 valve

Blow the pics up and look at how differently the locks grab the valve.

It looked like the correct (bottom) picture when I put them together, on all 16. Although it would have been nice to have been informed about the contents of the bag possibly being wrong I am not the head expert...
Too late now, I suppose. But I will check that too on reassembly.


Anyhow, can you please provide the part numbers of the valves? I don't know yet how many of which kind I need... thanks.

Did I send you new locks, or did you get them yourself?

The ones that are sticking up past the retainers(the ones coming out)....... are they 11/32 or 3/8?

If they’re the correct ones, then you have something else going on........ that you’d like to identify before reassembly.


Edit- I looked up your invoice.
I sent you locks, and what I sent were 11/32(611-16).

I haven’t had any mis-packaged locks from Comp until recently, so they’re probably not the cause of the issue since yours were from 3 years ago.
I’d still verify they’re correct.

The valves were from SI Valves.
Intake - 3556E-341
Exhaust - 3506E-341

At this point I’d say pull the heads and look for witness marks for clues as to what’s going on.

Just thinking........ since the worst one seems to be an intake ........ did you verify there is no pushrod contact with the heads inside the intake pushrod tunnels....... throughout the entire lift range?

That can be expensive forgetting!

I seen a big block stroker that was blown up in the garage last year because the heads were measured for -.050 retainers, and the guy ordered -.050 retainers AND locks, installed them and assumed it would be right.....

You are 100% right about that! I am not sure there's enough left of them (the fractured ones) to tell. How exactly can I identify them (is there a laser-etched part number in very fine print, or a particular measurement I could take other than just seeing if they fit snugly)?




Well, I'm surely going to have to pull the left one to replace intake #3!



Yes. There are no visible marks, or deposited aluminum on the pushrods, for any of the cylinders. With the plugs removed, I can turn the engine over freely with a bar and do not feel any binding. Once the head(s) come off, I will carefully examine the pushrod tunnels for wear marks

Shall I order new valves from you, or where should I buy them? If you send them, can you do the same back-cut as you did originally? Will save me a trip to a machine shop here...

Thanks for the suggestions.

He must have been running gnat's-ass p/v clearance if .050 caused a collision That's one good thing about my pistons, they have very generous valve reliefs.

look at the gap left between the keepers on one you haven't disassembled yet. There should be a gap at, at least one edge between the two keepers. A 3/8 keeper on a 11/32 valve will touch at both points.

No it involves much more that that but there is no need to describe the travesty. It was dropped valves due to broken retainers. Made my head hurt just trying to figure out what he did over the phone. It's just dangerous assume sometimes.

Thanks. There is a gap, larger if one of the halves is slightly rotated so the other edge touches... At least on the non-busted ones

Things are pointing to mistaken valve locks (keepers). If you reused the ones from the iron heads, they are likely for 3/8" valve stems. If you used the new ones from Comp Cams, hopefully they didn't package some 3/8 with 11/32. I have seen Comp put one or two wrong retainers in a package of 16 several years ago.

Thanks. That is my working theory at the moment. I'm thinking that the ones that came loose were 3/8, and the valve that dropped probably got two 3/8. Either that, or I fractured a couple during installation...

If you look upthread a bit, Dwayne (who did the porting and supplied the locks which I installed) says he's seen wrong ones in the packages from Comp before, but only recently. My job was completed over 3 years ago, I just now got around to installing the heads! I ordered a new set of 32 from Summit, so I will be looking very carefully at them.

No, I didn't reuse the ones from the iron heads - they are indeed 3/8" stems, and the exhaust valves are 3-groove instead of single
I may have been born at night, but not last night

Will take at least the left head off today (after pulling the steering column and header. Again) and get it on the bench.

This won’t help on the broken lock, but on the others, like those that are sticking up above the valves, an easy test to see if they are 3/8 or 11/32 is to see if they’ll fit a 3/8 stem valve.
If the iron heads had single groove valves, you can use one of those.

An 11/32 lock very obviously won’t fit a 3/8 stem.

A 3/8 lock on an 11/32 valve fits around the valve, but wobbles around.

As for the valves, I don’t stock them.
The easiest thing for you would be to just get them direct from SI.

https://www.sivalves.com

I believe Hughes carries them as well.