8MM retainers/locks on 5/16 valves: OK or not OK?

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Oe Magnum valve and locks with gen 2 hemi crate motor retainer:

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Well....... a customer sent me the heads off his MP 474(?) Hemi crate motor for some porting and a valve job, etc, to go along with some other upgrades he was doing to the motor.
The heads got updated with dual springs and 10* retainers and locks....... he didn’t want the old stuff back, so I put it in a box on a shelf.
Gen 2 Hemis also utilize 5/16” stem valves, and the retainers are 7* like the stock magnum, so I thought I’d see if they fit.
And it appears they do...... but it looks like you’d lose a little installed height.
 
I will undo a retainer when my on head valve spring compressor arrives from Summit along with the right locks (should be a few days) & I will get that dimention (lock groove up to the tip). Plus a salesman there is gonna check on a set of #4825 comp cams retainers for me as these I have (new) are junk & the 5/16 pushrods wont even fit in the guide slots
 
Marcohotrod said:
why are the new Lunati retainers junk? what locks do the valves require?
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I ain't sure what valves I used (way too many projexts going on combined with poor record keeping!) but they are 5/16 with bead lock (rounded bulges) in genuine new zealand EQ heads.
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I’m interested to see the lock groove situation of the valves myself.
If they are the same as OE magnum(like what I posted a pic of), I don’t think the Manley 10* locks are going to work.

I recently freshened a set of EQ magnum heads....... the customer sent me MP springs/retainers/locks that would be used on OE magnum heads.......everything fit just fine.

I think part of the problem here is, Mopar refers to the head components as “8mm”.
They are closer to 5/16” than 8mm........ but they are about the same amount under normal 8mm stuff as gen 2’s were under 5/16”.

LS 8mm valves are usually .313-.3135.
Magnum are typically .311.

If one were to test fit LS locks and retainers on the Magnum valves, and everything(valve/locks/retainer) locked into place, I don’t think there would be any problems running it like that.
 
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OK when I said CC 4825 "retainers" I meant to say "guide plates" & they are junk cuz on about 5 or 6 of the rectangular open ended slots for the pushrods (8 plates/2 slots per plate) they ain't even wide enough for the pushrod to fit in there let alone 5 tho clearance on each side of the pushrod. Other people have left similar reviews on the Summit site (the CC site wont let me enter a review/what a surprise). I ordered another set (from eBay/Summit iirc) & I am gonna port em out (I couldn't find another brand anywhere). I got the new locks from Summit: Manley #13151-8 (X2 boxes of em), says on the box: "bead loc for .3110" stem valves use 10 deg retainers standard installed" I mocked one up on a valve with the Lunati retainers & everything appears dead on & tight as opposed to the ~.020" back & forth clearance I had with the prior 8MM locks. Marco iirc asked about the distance from top of lock groove to top of stem & I got ~.100". The .050" I priorly mentioned was from top of lock(s) to stem tip (I was at the time potentially thinking lash caps for the roller not being centered/too close to ex side) tho Mike at B3 raceing does not recommend em. that is where I am at so far. RR
 
I just noticed that these locks (with the lash cap recess) actually are slightly higher than the valve tip so these will not work either. Any suggestions on a "no lash cap recess" set that will work? 5/16 10 deg & bead lock.
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are they +.100" retainers? throw some lash caps on. if the rockers sweep is good they do not hurt
 
IMO, This is a classic case of........ it’s hard to get the right parts because, you/we don’t really know what you have.

To that end....... still waiting for that groove to tip dimension, and/or a pic.
 
the top of valve stem groove to the top of stem dimention is .100" as close as I can measure. AFAIK they are "std" height retainers. I do have some old 5/16 lash caps I found the other day but the depth inside is great enough that they do not set all the way down flush on the valve stem (if that is an issue) & I do have a contact problem as the roller (on base circle) is too close to the ex side of the valve tip (sweep seems OK tho).
 
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the top of valve stem groove to the top of stem dimention is .100" as close as I can measure.
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So, the groove to tip situation looks like the pic I posted of the OE magnum valve?

If that’s the case, you might be able to get away with a -.050 10* lock(if you can afford to lose the .050 installed height) but fundamentally that type of groove would normally be used with locks that have the tang located at the top...... like the OE locks.

As for the lash caps, they aren’t going to work with that short tip length.
There needs to be clearance between the bottom of the lash cap and the locks, with the cap resting on the valve tip.
 
There needs to be clearance between the bottom of the lash cap and the locks, with the cap resting on the valve tip.
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That is what I needed to know. Thank you. Ok, "bare valve stem" there is .125" from top of single lock groove up to the (5/16) valve tip. With my current Lunati 77132 locks (no LC recess) & Lunati 75740 retainers installed there is .050" from locks up to valve tip (all good) but they are 8MM & some say no problemo & some say possibly or highly likely. I have some manley 5/16 locks #13151 but with mocking them up the perimeter for the lash cap recess that these have is .017" above the valve tip (in the pic). I got antzy today & ordered comp cams 5/16 lash caps 619-16 which is a "Hemi .050" short cap" (their descrip) but I would much prefer to get the right locks on there & no lash caps but Gregory from Summit & Kiera from Manley we had a 3 way conference call this afternoon after me & Greg talked several days in a row regarding this & evidently no short caps available so I wanted to do something! That is where I am at so far. RR EDIT yes I can afford to lose some installed height
 
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You could always grind some off the bottom edges of those lash caps; if it does not touch the keepers, then the edge finish is not critical. But I'd be a bit antsy of one/some flying out if things floated just a bit, being so shallow now. Is this engine going to see higher RPM's? Sounds like it....
 
On the moparts thread you said the lunati 8mm keepers and retainers won’t
lock onto the valve.
If that’s the case, those parts aren’t going to work.
 
Lunati swears that the Lunati 75740 retainers and the Lunati 8Mm locks will work & others said if they fall down on the stem under their own weight then they will not (& they did). I got some different Lunati locks 13151 (for 5/16 valves) but the lash cap recess perimeter is .017" above the valve tip. Agreed I am gonna try (maybe) grinding the 5/16 lash caps I already have as CC/Manley & Lunati after many ph calls have nothing that they can find that will solve this. The CC 5/16 lash caps I ordered yesterday I found out today will not work cuz the .080 (posted) dimention is the inside dimention not the total height. This will be a circle track eng buzzing to maybe 6300 tops. If you guys think I can get by with some 7 deg retainers/locks in this app (142 lbs closed/308 lbs open) maybe I will have better luck. There is .125" from the top of the (bead) lock groove to the top of the valve. I am certainly open to advice/suggestions/guidance! I am hitting the wall here! RR
 
The way I see it, it’s really pretty simple.

The person assembling the motor is the final check on making sure things are as they should be.

If you’re confident the lunati parts will work, then run it.
If you’re not, you have to find an alternative.

It doesn’t matter what anyone on the other end of the phone says, or what someone on the internet says.
They don’t have your particular parts in front of them to be able to make that judgement call.

If you’re putting it together....... then the final say is you.
 
What is the depth of the lock 'bead'? And the depth of the groove? I ask as from the dimensional info given, there is a radial different of .00125" between the locks. In the center of the locks they will probably lock in well... towards the ends, they will not be tight, but again, should only be .00125" out of fully inserted in the groove (or fully inserted on on end and .0025" out on the other end). That still leaves most of the width of the bead bearing the load.

308 lbs open is not all that high. It'll just be spending a lot of time there...

I suppose the concern is that the locks may shift back and forth, or just never be snug, and in case things float a bit, they might be more prone to pop out. But if you put 2 layers of standard duty aluminum foil between the keepers and valve (just over .0013" thick) to fill in the gap, it might just lock in snug and not move. Not necessarily saying to do that, but it's an idea of how small the gap is.....

BTW I saw in my .pdf Lunati catalog the 77118 and 77117 10* locks, which are listed for .310" valves (as opposed to the 77110 type which you started with and is listed as being for .308-5/16" valves). I do not know if these are square or bead lock types.
 
I ran 7 degree locks on 3/8" valves to 7000 rpm for 15 years with a flat solid cam and 335 open load and .570" lift - no problems
 
OK, the Crane 99121 locks arrived (5/16 10 deg & lash cap recesses (& I am useing the original Lunati 75740 retainers that they (Lunati) say are OK with 5/16 or 8MM valves) ???. The girl at Crane said that the distance from the "center" of the bead lock bulge in the locks up to the tip of the lash cap perimeter in the locks is .110". Since I got .170" from the center of the bead lock concave recess in the valve stem up to the tip of the valve stem I figured this would solve it. WRONG! Upon mockup the L.C. perimeter is flush with the valve tip (maybe the tip is .001 or .002" above the perimeter) so I said enough is enough & I ground down about 2/3 of the lash cap perimeter so the valve tip is up higher than the LC perimeter. A noted builder said to mockup a retainer/pair of locks on a vertical valve (no spring) & let loose & see if they fall (this was a test for the prior 8MM Lunati locks I have) & if they are loose under their own weight then there is an problem & it fell pretty loose but now these "correct" 5/16 locks doing the same test are even looser! & these comp cams locks appear to be poorly machined junk compared to the Lunati works of art (8MM tho). Lunati does have 5/16 ones but they have lash caps which I wanted to avoid but I thought I'd be quite a bit to the good with the dimention she gave me, but I can certainly buy a set & same thing trim the lash cap perimeters cuz they look real nice quality (if you guys say this is a good move). I was thinking if I mighta messed up the heat treatment by grinding on these CC locks but I tried to go slow but I didn't go as slow as I should have (I was seein the light at the end of the tunnel)!. That is where I am at at the moment & I am for sure still very much open to advice here. Thank you. RR EDIT & these CC 99121 locks have alot & I mean alot of "gap" between the "ends" up top that you dont want to be butted. Not sure if that is a good thing or not, with the gaps "even" on each side there is alot of clearance.
 
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with a pair of the new crane (not CC, my prior posting mistake) 99121 locks & a pair of the lunati 8MM locks alternately held on the stem (by them selves) with my fingers I can move the locks up & down ~.020". (neither set "appears" to be tight).
 
I can't say I have ever paid attention to that dimension. I'll have to check a few locks and valves at some time after I get back home. That matches what you found in post #19.

As long as there is spring tension on the retainer, the locks would be held solidly up against the upper edge of the valve's groove. The only time they could possibly move down in the groove is if some severe spring vibration actually made the spring momentarily contract a tiny bit. What valve spring arrangement are you using?
 
This is for single groove valves......
The thing most people get wrong is assuming the “tang” on the locks are taking all the load from the spring.
They’re not.
The squeezing of the locks against the valve is what does most of the work.

The retainer, locks, and valve should all “lock” together under tension.

It’s not that uncommon for me to see locks with the tangs almost sheared off because of a poor “interfit” with the retainers/locks/valves.
And many times when that’s been going on, the upper edge of the groove in the valve gets rounded over...... so then you also need new valves.

If you take the stock magnum valve, retainers and locks, assemble them together with a little upward pressure...... they’re “locked”.
You can bang the valve down on the bench firmly and they won’t come undone.

That’s how they should be.

Sometimes with aftermarket parts it takes a bit more force to get the parts locked together.
If you can get the pieces to lock using a height mic on the heads when you’re setting up your springs, even if it takes a little tap with a brass hammer........ that’s okay.
But when you do it that way, and you back the height mic off....... it should take a little effort to unlock the pieces.
If you undo the height mic and the pieces fall apart....... and you put it together like that........ don’t be surprised if it fails, or if the parts are all toast when you pull the heads apart next time.

Even with springs that are close to 400lbs closed, being used with .900 lift cams and over 1000lbs open load...... if everything has the proper interfit, there will be essentially zero wear marks on the tangs in the locks when the heads are taken apart for freshening.

I’ve also seen poor fitting parts run with springs that are only 100/280 that were on the verge of shearing off what little of the tang was left.

When the factory decides they want the valve to float in the locks(instead of acting like a collet), and are going to rely on the tangs to bear the load........ they use 3 or 4 tangs(like the stock 4 groove ex valves) ..... and then keep in mind they’re also being used with really mild cam profiles and modest spring loads.
 
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That makes a ton of sense; thanks. I had worked out the lateral pressure, but did not know that was the primary hold force.

But if that is the case, why would the tangs get 'almost sheared off' with poor fitting parts? Just a bad diameter match between lock ID and valve OD? And how far off is a 'bad fit'? That seems to be RR's main issue at this point: not being able to find an exact diameter match between locks and stem.

It seems to me that if they are not perfectly matched, then it would be better to have the lock's ID a bit smaller than the stem's OD, rather than vice versa. In that way, the retainer would press in on the locks and you would end up with 2 points of pressure from each lock against the stem.
 
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