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Rocker contacting top of retainer on vortec heads

32K views 74 replies 11 participants last post by  flyingputz 
#1 ·
I don't mean to beat a dead horse, but here's my dilemma. I thought I had this ALL figured out. I've got the #906 vortec heads, Comp 26918 springs(recommended installed height 1.80") 787 retainers and +.050 locks. This gave me my necessary height and retainer to seal clearance, with NO machining. I don't like the idea of taking away that much material from the guides and seat, especially since the guide is ALSO the spring locator. I don't even know if ANY material can be taken away from seat to increase installed height? Now my rockers are contacting on many of the retainers. If I put the standard locks in place plenty of valve tip is available, however, that takes away my retainer to seal clearance AND increases my seat pressure to approx. 144 lbs. I feel my only option is +.100 longer valves. I will take up any extra height with -.050 locks OR shims. I know I'll have to keep the geometry correct at final assembly via pushrods. BTW, cam is 222-230 dur. .509/.528 lift @ .050 with 1.5 rockers. I'll be using Comp 1.52 rollers(self aligning). Screw in studs are already in place. As stated, I already have ALL these parts. Any thoughts or suggestions greatly appreciated.
 
#47 ·
With rocker centered over valve tip it contacts lock, but if rocker is slid across tip 'til the rail stops its lateral movement the opposite rail WILL contact the retainer. I've got Comp #787 7* retainers for the beehive springs. I trimmed down the tops of a set of the +.050 locks to see if I could skate by, but no go. MOST of the locks are FLUSH with the retainer. On the few where the lock actually sat higher than the retainer this theoretically might have worked. However, trimming ANY material away from such critical components is probably not a good idea. I'd rather spend a bit more money and play it safe than gamble catastophic failure. My initial objective was to upgrade these heads without doing ANY machining (other than screw in studs). Easier said than done! There are a LOT of misleading articles out there on vortec head upgrades which supposedly require no machine work.
 
#48 · (Edited)
I don't recall, what rockers are you using? Agree on misleading info. But there's something that is somehow different about your set up that is causing the problem; there are a lot of guys using everything from stock retainers to the same set up you have to going back to the early-style valves and retainers (less damper) that all work w/SA rockers. So my theory is there is (at this point, anyway) the rocker arm might be the fly in the peanut butter.
 
#50 ·
My c/n 062 heads have plenty of clearance and the tips are not 0.290- which is supposed to be only on the exhaust, anyway. I suspect the valves were resurfaced and this caused the tip lengths to be shorter than 0.260" intake/0.290" exhaust. The rockers clear them just fine. So the tip length is not ordinarily a problem.

If this was a universal problem, there would be thousands of reports of this being a problem. But there aren't- because it isn't a universal problem. There's something peculiar about HIS set up that is causing the problem, I believe it's the rockers he's using, or the geometry of the valvetrain (which hasn't been addressed AFAIK).
 
#51 ·
The O-ring groove was eliminated on the 1996-2000 062 and 906 Vortec valves and a different retainer without a shield was used.

The 906 Vortec heads were equipped with hardened exhaust seat inserts which resulted in a increased valve seat margin compared to the intake seats. The increased exhaust valve margin made the exhaust valve sit lower in the head. It was corrected by making exhaust valves with longer tip lengths. The keeper groove was the same distance from the valve seats.

In order to maintain equal valve stem heights , the O-ring groove, O-ring seals and oil shields were eliminated on the Vortec valve stems and the retainer lock grooves were relocated. The tip lengths were changed from .250" intake and exhaust to .289" on the exhaust valves and .260" on the intake valves. The valve face and seat angles should be ground in order to establish the valve margins at .050" intake and .080" exhaust to allow for the difference in valve tip lengths.
 
#53 ·
Thanks for the info, I have not seen this tip/seat info here previously. If it can be verified (not doubting you; got any links?) I will include it in the wiki.

My heads are 062 w/induction hardened exhaust seats. It may be that standard Vortec tip valves were used in non hardened insert Vortec applications; there's no sense in using a too-long tip to correct for a problem that doesn't exist on non hardened insert-equipped heads- this would be as bad as using a too-short tip on an insert-equipped head.

However I believe discontinuing the O-ring/metal shield was unrelated to going to a single groove stem; the O-ring/metal shield simply isn't needed when using the Vortec valve stem seals. I believe they opted for the better seals for emissions and cost savings as much as anything, secondarily for any other reasons.
 
#52 ·
I have to admit that after 4 pages of this I'm getting lost.

So if you still have the problem let me state my understanding, or lack, of it.

I take that you have self guided roller rockers and the self guiding guides that are like washers located to either side of the roller which contacts the valve stem are themselves touching the spring retainer. Is this correct?

The other choice open to interpretation is that the body of the rocker contacts the spring retainer. Is this what's happening?

Neither situation is desirable, nor acceptable, but the causes and solutions of each are different.

Neither of these problems have much to do with the installed height of the valve, not that this can be ruled out but for the valve to be sitting deep in the seat from an exuberance of seat grinding to the head or valve, or both, would have to be very extreme to have such a huge effect on the angle of how the rocker address the valve stem as to put parts of the rocker into contact with the spring retainer or the locks. Sinking the valve seats (head and valve) forces the stem to ride higher in the guide. This moves the lock position (thus the retainer) further from the spring seat resulting in the installed length of the spring to be longer than specification which in turn relaxes the spring reducing the forces it will generate toward keeping the valve train following the cam lobe and holding the valve in the closed position. Typical flat rate shop work for this situation would be to shim the spring between the spring pocket and spring is the usual solution toward making the effective length of the spring shorter so the correct spring length is established between the bottom of the retainer and the top of the shim. The valve tip is often ground to restore the installed height of the stem to the valve spring pocket to restore the rocker angle and position to the stem tip. But this shortens the clearance distance between the lock grooves and stem tip; thus also ,where the retainer positions from the stem tip, this can get you into clearance problems between the retainer and rocker or in the case of self guided rockers the lesser distance could put the guiding bosses or washers into contact with the retainer. As an aside this is a common problem with older Ford SBs where rocker tip and stem tip wear closed the clearance till the rocker guides rubbed on the retainer, which risks pushing the retainer low enough to allow the locks to pop out dropping the valve into the cylinder.

Obviously trying to avoid shortening the Vortec's tall guide boss to provide additional lift clearance between the assemblage of the retainer, stem seal, and stem guide by sinking the valve deeper in its seat is not the way to solve this clearance problem as it gets you into the problems I describe above. When I read your comments through this; I get the feeling that this approach could be involved. Did you do this?

It is always possible that the lock angle of 10 degrees or 7 degrees does not agree with the interfacing angle of the retainer. This would cause the retainer to sit improperly as a position to the stem tip and affect spring installed length. Did you check these parts to be sure they have matching angles?

Roller rockers especially cast ones tend to be fatter than stampings; it is not unusual to have to grind a clearance into their body to clear the retainer especially where oversized springs are used.

The angle the rocker makes with respect to the retainer can also be an issue; if the studs are too short there usually isn’t enough bite for the stud’s threads into the retaining nut which can result in thread failure. Solution is a longer stud which for sure will force a longer pushrod. Or if the pushrod is too short because the valve stem sits higher than designed then the rocker sits at a low position with a sharp angle between the push rod and stem tip that can get it into contact with the retainer. The solution is a longer push rod.

If everything is dimensionally correct and the witness marks on the stem show the roller to be properly positioned on the stem sweep but the guide washers are riding on the retainer then one can consider several possibilities are causing the stem clearance distance to be incorrect:

- This can be a result of the lock's location of the tang being other than what you expect; there are locks that move the tang up or down .050 inch being typical from the OEM position. These are often relieved for lash caps which will allow their use with roller tipped rockers. You also need to be sure the locks are the proper diameter for the valve stem. Between .310, 8mm (.3150), .3437, .375 inches there's getting to be things that are close but not necessarily correct for what you're using, so you've got the check stuff before using it.

- The distance between the lock groove and the stem tip is insufficient. Typically the SBC valves come in a .225, .250, or .290 inch clearance. Don't go by what documentation says should be there use what provides the needed clearance. Often the overall length is held at a constant and this clearance is moved by relocating the lock groove, this is done to play with spring length as a means of adjusting pressure between the weight differences of intake and exhaust valves. More engineering refinement than is probably necessary for anything short of a race engine. Use this to get the rocker correctly positioned. Keep in mind that longer valves does not mean the relationship between the lock groove and stem tip changed but is just moved further from the valve head and seat. Some heads are .1 or .2 inch taller between the seat and the spring pocket and need an overall longer stem to restore the spring length to retainer relationship. This doesn’t change the groove to stem clearance aside from placing that relationship further from the valve head. This will require longer pushrods because it changes the rocker’s position from the head deck (makes the engine taller is at were) but does not necessarily change the dimensions between the bottom of the spring retainer and the top of the spring pocket, I mean it can, but doesn’t have to. The production Vortec head should require this kind of messing around unless you’re trying to get space for more lift without grinding down the guide. In that case you get into a lot of problems not unlike where you’re at. Did you do this?

- The guide washers are too large, given the quality issues I see almost everywhere anymore it could be that the guide washers are bigger than needed, I guess I could say grind them down, but I wouldn't do that except as a last resort after checking and adjusting everything else first.
I know it’s hard to believe, but I’m out of words and will be out for the weekend. So good luck with this.

By the way, a hydraulic lifter will chase any gap that opens up in the valve train parts till the plunger runs into it retainer (bail or clip). This is what a pumped up lifter is all about. A space appears between the parts for any reason, the lifter closes it. If it was adjusted properly there's about a .020 to .030 gap between where it's running position is and its retainer. When it closes that space the next time the valve goes to close it can't, it's hanging .020 to .030 off its seat till the lifter bleeds down and returns to its normal preload clearance.

Bogie
 
#54 ·
Well, after much thought heres what I've decided to do. I'm gonna ditch the +.050 locks in favor of standard locks. This gives me plenty of valve tip to work with. I'll machine the guides down a bit to give me the necessary retainer to guide clearance, and live with the slightly increased seat pressure( up from 130# @ 1.80" installed height to 145# @ 1.75" installed height). I'll still be safe from coil bind and my open pressure will be in line(342# @ 1.20") A guide cutter and new seals is a helluve lot cheaper than the new valve order I cancelled. That and I had just gotten a valve job done on them a month or so ago. The proverbial "fly in the ointment" was the +.050 locks. They just won't work with .25" valve tips and self aligning rocker arms. Dare I ask, anyone see issues with this or does it seem the logical thing to do?

BTW Cobalt, the stamped rockers were contacting locks/ retainers also
 
#55 · (Edited)
The +.050" locks will shorten the effective valve tip length.

If you do not want to go to the expense of purchasing valves with .290" tips, use locks designed with a recess for lash caps...... but do not use the lash caps. The lash cap recess will proved a little more clearance for the self aligning full roller rocker rails. I ran those type locks for about 4,000 miles with Scorpion narrow body, self aligning, full roller rocker arms before I installed better heads with Manley SS valves that had .290" tips. I inspected the locks and rocker arms regularly because I realized that was not the best way to solve the problem. Unfortunately, lash cap locks will not help if you are using stock self aligning rocker arms. The alignment nubs on the stock self aligning rocker arms are too large.

I would probably have still been using the Comp Cams 10* Super locks designed for lash cap locks if I had not installed the better heads I had prepared with Manley valves. I replaced the 10* lash cap locks with standard 10* Super Locks and have .035" clearance between the rocker rails and the locks. .
 
#58 ·
The Comp Cams 1317 rocker arms have the alignment tabs on the rocker arms rather than on the roller tips. That makes them about .020" wider between the alignment tabs. That will cause the rocker arm alignment tabs to contact 7* retainers rather than the locks. The alignment tab location and not being narrow body for center bolt valve covers were the reasons they were taken out of production. They are rebuildable but apparently that was not a good selling point.

If you use 10* locks with a lash cap recess (and 10* retainers), the 1317 alignment tabs would fit inside the lash cap recess and may offer a bit more clearance. That is not the best way to get more clearance but it is cheaper than buying a set of Manley SS valves with .290" tips or buying a new set of aluminum, narrow body, self alignment rocker arms.

I used Scorpion 1073BL full roller, self alignment, narrow body, aluminum rocker arms. Those rockers have the alignment rails on the roller tips. They measure 0.350" between the alignment rails and better fit SB Chevy 0.343" (11/32") valve stems with negligible (0.0035") side to side movement. I am using Manley valves with .290" tips. The rocker arm alignment rails have .035" clearance from the 10* locks.
 
#61 ·
Through all of this thread, and it is a thread and a half, I've gathered that inorder to eliminate the clearance issues between the rocker and locks and rocker and retainer for a stock Vortec head with .500 to .525 lift the solution is valves with .290" stem height above the the lock - is that correct? And this should eliminate the need to machine the guides for retainer clearance and spring pressure will be relatively easily adjusted with shims, correct? And from there I will have to get the correct stud and push rod lengths.

From what you guys have posted, this will work with several different brands of self aligning roller rockers and ratios.


I ask, as I am planning on a Vortec head install with a set of 062's that I already have.

FYI - I don't want to hijack the thread, but this will help me from finding myself in flyingputz's situation (and you guys from answering the same questions again in 4-5 months).
 
#62 · (Edited)
If you choose springs and retainers that will give the correct pressure and installed height using standard locks, there will very rarely be a clearance issue. A couple examples (there are others) are Crane p/n 10309-1 (good to 0.550" lift) if you can deal w/the ~$250 cost. These are $100, good to 0.550" lift but I know nothing about them other than his reviews on eBay.

The problem that's been encountered here is the exception, not the rule. flyingputz had a problem because he used locks that added 0.050" to the installed spring height because the springs he used had a little too much seat pressure without the added height. The added installed height the locks provided also reduced the clearance between the locks/retainer and rocker arm.

Ideally, the 26918 springs (130 lb @ 1.8" installed height) would be used w/+0.100" valves. Another way around this would have been to use guideplates and ditch the self aligning rockers or use guideplates w/the rockers he has now, after removing the alignment 'rails' from his rockers (shown below). Then the +0.050" locks would clear.

If the rockers were the type that used the thin "washers" on either side of the roller for aligning on the valve tip, this might not have been an option. I thought this was what he had after it was mentioned by someone but it turns out they're the cast-in rails that could be removed. After seeing his rockers and thinking it over, that's what I would do, along w/using the +0.050" locks. It would be time consuming, but using care it can be done. I'd use a dremel and run several turns of mashing tape over the rollers to help protect them. Obviously this would require guide plates, different studs and the boss cut down, but I believe that would be the least expensive way to go about it, other than to just go ahead and run a little extra spring pressure.

 
#66 ·
I don't think that added height above the lock groove is of any help with clearance between the guide top and bottom of the spring retainer.

There are several situations going on each needs to be understood differently.

- The first is the distance between the valve's head and the lock groove on the stem. This can be independent of the total length of the stem as measured from the head to stem tip. So this is a value you need to know as it doesn't have to change just because the valve is longer. But it could so you cannot make an assumption; you've got to have the measurement. Many valves are sold at .1 sometimes .25 inch longer than stock. These usually but not always are intended for aftermarket and OEM over the counter performance heads that raise the port which also raises the spring pocket. These valves often raise the lock groove a like amount to the stem length increase so as to retain the production part installed spring length. They might retain the production distance between the lock groove and the stem tip.

- The second is the distance between the lock groove and the stem tip. This is independent of the valve length but may be married with a longer valve.

There are problems encountered when trying to avoid shortening the guide height on Vortec heads by using a longer stem and shimming the spring:

- A thick shim needs to be placed under the spring and a separate spring locating pad will have to be included in the stack up.

- Longer stem lengths are more unstable they bend especially with increased spring pressures.

- The rocker studs usually prove to be too short because the longer valve forces raising the rocker. You will have to obtain longer studs. At this point longer studs become unstable with high spring pressures you may well find that you must use a 3/8ths stud and maybe even girdles to keep even a street engine from having problems busting studs.

- You will have to also use a longer push rod to keep the geometry of the rocker at the valve stem tip correct. This probably can't be ascertained until after engine assembly so all the dimensions can be accounted for in the tip sweep.

So as you can see a lot of elements come into this when you try to get around grinding down the guides.

Over many decades I developed a deep understanding Murphy's Laws of engineering and mechanics and added a few corollaries of my own, one of which is:

- The easy way out of a problem always leads back in and at greater expense.

Frankly, I'm rather of the opinion that if you're planning .5 inch lift or more the production L31 Vortec is not the head to be using. There are many aftermarket heads that just don't require so much messing around with for about the same price.

Bogie
 
#67 ·
So as you can see a lot of elements come into this when you try to get around grinding down the guides.

Over many decades I developed a deep understanding Murphy's Laws of engineering and mechanics and added a few corollaries of my own, one of which is:

- The easy way out of a problem always leads back in and at greater expense.

Frankly, I'm rather of the opinion that if you're planning .5 inch lift or more the production L31 Vortec is not the head to be using. There are many aftermarket heads that just don't require so much messing around with for about the same price.

Bogie
I'm not opposed to machining the guides, even though it sounded like I was. It was just the way it came out. Machining the guides isn't expensive and it solves a lot of issues from what has been mentioned in this thread.

I agree that the easy way is usually not the best way and also usually ends up with me reworking the original problem. I'm sure that you have been bitten by the 'take the easy way out' snake a time or two.

In terms of going more than .500" on a stock Vortec head, I always have to remind myself of what I'm after - 350 to 400 hp street machine. I'm not a drag racer, I'm more of tire burner. Presently, repeat presently, I believe the cheapest route to my HP desires are through a Vortec head. I have to admit that I would love to have a 500+ HP motor in a daily driver, but I am aware of the problems it creates. Personally I find more satisfaction in cheap HP. I know that alot of people on this forum aren't after what I'm after, but 'to each his own'.

Lastly, 'corollaries'? You made me use the dictionary!:D

cor·ol·lar·y (kôr-l r, k r-) n. pl. cor·ol·lar·ies. 1. A proposition that follows with little or no proof required from one already proven.

Thanks greatly for the advise:)
 
#68 ·
I'm not opposed to machining the guides, even though it sounded like I was. It was just the way it came out. Machining the guides isn't expensive and it solves a lot of issues from what has been mentioned in this thread.

I agree that the easy way is usually not the best way and also usually ends up with me reworking the original problem. I'm sure that you have been bitten by the 'take the easy way out' snake a time or two.

In terms of going more than .500" on a stock Vortec head, I always have to remind myself of what I'm after - 350 to 400 hp street machine. I'm not a drag racer, I'm more of tire burner. Presently, repeat presently, I believe the cheapest route to my HP desires are through a Vortec head. I have to admit that I would love to have a 500+ HP motor in a daily driver, but I am aware of the problems it creates. Personally I find more satisfaction in cheap HP. I know that alot of people on this forum aren't after what I'm after, but 'to each his own'.

Lastly, 'corollaries'? You made me use the dictionary!:D

cor·ol·lar·y (kôr-l r, k r-) n. pl. cor·ol·lar·ies. 1. A proposition that follows with little or no proof required from one already proven.

Thanks greatly for the advise:)
Going through having taken the easy way out last May, it's back biting me in the tail this week. Wish I took my own advice.

Bogie
 
#65 ·
The Manley valves with .290" tips will work with aluminum self aligning rocker arms. You will have about .035" - .040" clearance between the rocker rails and valve locks. We used Comp Cams 795 retainers Comp Cams 613 locks. That is 10* equipment. The 10* locks are wider than 7* locks which gives additional clearance between the retainer I.D. and the rocker alignment rails.

The push rod length and rocker arms stud height are different issues. You will need to determine the correct push rod length after the camshaft is installed. There are several different 3/8"-24 rocker arm studs that have a different effective heights in order to get the correct adjustment length for the poly-locks. We used ARP 134-7104 rocker studs which is the most common suds used for full roller rocker arms and poly-locks. .

The push rods we used were Comp Cams High Tech #7940 (7.200" ) but the length must be determined for your heads using your lifters and camshaft.
 
#70 · (Edited)
64nailhead or anyone else interested in Comp seat & guide cutters with 11/32" arbor? Used on just ONE set of vortecs. Worked like a charm! I'm finally back on track with this build. Cobalt, what determines whether or not distributor needs to be recurved? I've got GMPP (AC Delco) dist #93440806.

P.S. Just read your 'recurve' link.
Answered my question. Thanks!
 
#72 ·
I thought this thread was done, but guess what? I figured I'd buy some Comp hardened, machined #648 STANDARD locks, rather than reuse the FACTORY standard locks. Upon reassembly, these Comp locks actually give me 1.80" installed height, while giving me .025+ inch rocker rail to retainer/ lock clearance! The FACTORY vortec locks were giving me a 1.755" installed height! SO many variables in cylinder head rebuilding. Needless to say,after the unnecessary guide machining I now I have WELL over .620" retainer to seal clearance. Thought this info may be helpful to others.
 
#73 ·
I overlooked the fact that you were using FACTORY locks and retainers. Factory locks and retainers are designed for stock valves that have 8mm stems. If you use stock retainers and locks with aftermarket valves that have 11/32" stems, the locks will not fit correctly and will likely fail. That is the reason the stock valve locks and retainers sit higher on the aftermarket 11/32" valve stems. The ends of the locks were in contact with each other and did not provide the necessary clamping force on the valve stem. The ends of the locks should never be in contact with each other.

The combination of CCA-787 (7 degree) retainers and CCA-648 (7 degree) locks are designed for aftermarket SS valves with 11/32" valve stems and will fit properly.

I am using CCA-795 (10 degree) retainers, CCA-613 (10 degree) locks, CCA-26918 beehive valve springs, Scorpion 1.5 full roller rocker arms and Manley Race Master SS valves with .290" tips. That combination provides .035" to .040" clearance between the rocker roller tip alignment rails and the locks.
 
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