Valve spring/retainer question

[Michael G.]

I've been having some problems with components in the valve train on my L84. The engine was supposedly rebuilt close to stock, with an aftermarket version of the 097 cam. Since I know only enough about the subject to be dangerous, I've been reading up in the archives and elsewhere on line, to try and gain a better idea of what might be causing the problems.

I found two issues I'm concerned about. They might be critical, or, of little importance, I haven't got any idea:

The first, is about the spring retainer: I read that "the retainer must fit tightly into the spring". Mine are very loose. Does that really matter? If so, what problems do ill fitting retainers cause and how do i find proper ones?

The second: The valve springs in my engine are of unknown origin, They are similar in free height, but almost 50% stronger than new Sealed Power VS-677 springs (that are supposedly identical to the originals in the L84 engine) that I had tested.

Can pulled rocker studs (and a broken push-rod after the studs were screwed in) be caused by either of these issues?

Thanks, Mike

[Duke W.]

Re: Valve spring/retainer question

with an aftermarket version of the 097 cam.

They are similar in free height, but almost 50% stronger than new Sealed Power VS-677 springs (that are supposedly identical to the originals in the L84 engine) that I had tested.

TWO RED FLAGS!!!

First there is no such thing as an "aftermarket version" of the 097 cam. It is either an exact OE replacement - built to the GM print -like the Speed Pro CS113R - or it's a different design.

This cam will rev to 7000 with the VS677 springs anywhere near the installed height recommendation. It does not need higher rate springs, but higher rate springs and an aggressive dynamics aftermarket cam is a sure fire formula for pulling rocker studs.

It also sounds like the springs don't even fit the retainers.

It looks like you got screwed by some "engine builder". Welcome to the club. There are hundreds if not thousands of other members.

The only solution is to replace all the aftermarket junk with exact to print OE replacement parts, which are usually also the least expensive parts available. A set of those VS677 springs is about 20 bucks, and the cam is about a hundred. Get some new OE replacement retainers and locks, too. The springs, retainers, and locks are the same as your grandmother's 283 2 bbl.

Thrust me, those mostly long deceased guys who designed and developed the SBC through the sixties were whizzards, and there are damned few people, today, who can outdo them!

Duke

[Joe L.]

Re: Valve spring/retainer question

I've been having some problems with components in the valve train on my L84. The engine was supposedly rebuilt close to stock, with an aftermarket version of the 097 cam. Since I know only enough about the subject to be dangerous, I've been reading up in the archives and elsewhere on line, to try and gain a better idea of what might be causing the problems.

I found two issues I'm concerned about. They might be critical, or, of little importance, I haven't got any idea:

The first, is about the spring retainer: I read that "the retainer must fit tightly into the spring". Mine are very loose. Does that really matter? If so, what problems do ill fitting retainers cause and how do i find proper ones?

The second: The valve springs in my engine are of unknown origin, They are similar in free height, but almost 50% stronger than new Sealed Power VS-677 springs (that are supposedly identical to the originals in the L84 engine) that I had tested.

Can pulled rocker studs (and a broken push-rod after the studs were screwed in) be caused by either of these issues?

Thanks, Mike

Mike-----


You can still obtain the EXACT original valve springs used on your engine. They're GM #3735381 and they carry a GM list of about 10 bucks, each. You should be able to buy them for about 8 bucks, each, though, so a set will only cost about 125 bucks.

The original caps were discontinued a long time ago and replaced by GM #10038209. The latter are virtually identical to the original caps and will work perfectly with the above-referenced springs. These are about 4 bucks, GM list, but you should be able to buy them for about 3 bucks or 48 bucks a set.

Original locks ("keepers") are also discontinued but are replaced by GM #24503856. These are kind of expensive at about $3.50 each.

If it were me. I'd use all of the above GM parts, even though they cost more than aftermarket. I do not think that any of these parts are the same as those available in the aftermarket, even from major brands.

By the way, 1955-66 small block valve springs and retainers are not the same as 67+.

[Graeme B.]

Re: Valve spring/retainer question

Duke, you said 'thrust me', I trust you meant 'trust me'.

[Michael G.]

Re: Valve spring/retainer question

Joe and Duke

Thanks for the input. The up side is that I'm getting really good at disassembling and reassembling 63 Corvette engine compartments.

My primary concern here is to do the job right, with the proper parts, using a machine shop with some recogized expertise in the field. I thought that's what I was doing last time, but, I guess I'm finding out he hard way that "buyer beware" is a adage that never goes out of style.

I'm temped to do do the whole engine again myself now, because I have all the right equipment and I care about the result. Unfortunately, it been 30 years since I messed with the innards of a 327, and I don't want to screw up a 47-year-old engine, so I'll probably have it done by a rebuilder John Hinckley recommended, and re-build another 327 I have, to re-learn the process.

If you guys have any further advice on how to proceed, I'd sure be glad to hear it.

Thanks again, Mike

[John D.]

Re: Valve spring/retainer question

Michael, I believe you told me you have Dukes favorite CS113R cam in your 63. Now that is confusing in itself as old JD thought Dukes favorite cam was the LT1.
I feel bad you are having so much engine issues. My 63 engine was rebuild in Boardman, OH and I have no issues at all. Nice CS113R cam with AT992 lifters.
If GM has the parts and money is no problem then give them a try. Also make sure you do not have a high pressure or hi volume oil pump. The stock oil pump is all you need. Good luck, JD

[Michael G.]

Re: Valve spring/retainer question

John, I think I have an Elgin E-900-P cam. I called Elgin and they told me the grind was an "OEM" grind that matches the CS113R (and the original 097 cam).

I measured the lift while it was in the engine and got .262 intake and .266 exhaust. It was difficult to use the rough surface of the valley casting as a datum, so the last digit is suspect, but I think these are the correct lifts for the 097.

Since the cam seems to be correct, (without measuring ramps or durations) at this point I'm going to try the proper springs and retainers and see what happens. If I break something else, we''ll pull the whole thing out, fill it with Quik-Crete and use it to anchor my boat (not really, we'll just have real pro go through the whole engine thoroughly).

I'm off to find the retainers and stuff. Thanks

Mike

[Duke W.]

Re: Valve spring/retainer question

Mike-----


You can still obtain the EXACT original valve springs used on your engine. They're GM #3735381 and they carry a GM list of about 10 bucks, each. You should be able to buy them for about 8 bucks, each, though, so a set will only cost about 125 bucks.

By the way, 1955-66 small block valve springs and retainers are not the same as 67+.

The VS677 (3911068) that went into production in '67 has a very slightly higher rate than the earlier springs, and I recommend them for all rebuilds, especially when you consider the price of the ...381s. GM sells very few of these I'm sure, and increases the price every year to cover inventory carrying costs.

If you are going to completely rebuilt the engine, get some better connecting rods. If you want "more power" massage the heads and use the LT-1 cam. The archives are your friend.

You can buy virtually any exact to print OE replacement part from NAPA and most other parts chains. They are the same parts sold by GM usually manufactured by Federal Mogul or Dana under the Sealed Power and Clevite brands.

The nominal lobe lifts of the Duntov cam are .2626/.2665", so it does sound like you have an exact OE replacement, but you should research the Elgin part number to get all the specs and compare to the Duntov. All you have to do is order a set of Sealed Power springs, retainers, and locks. You can get the part numbers from napaonline.com either via cross referencing the OE or GM replacement number or searching by make/model year and order them through a local NAPA outlet. There's no need to run all over town looking for parts.

It's incomprehensible that some "enginer builder" would install a set of gorilla aftermarket springs with a Duntov cam, but this kind of moronic thing happens all the time.

If you have "positive" type valve seals you don't need the shields. If the engine only has the OE type O-ring to keep oil from draining down from the retainer, you need the shields.

Duke

[Joe C.]

Re: Valve spring/retainer question

If you have original type o-ring seals, then you only need the shields if you are not using the "umbrella" seals as well as the o-rings.
It is wise to eliminate the metal shields in favor of the "umbrellas" so as to reduce inertial weight on the valve side of the rocker arms. This reduction goes a long way in enhancing valve control (i.e: minimizing valve seat bounce and valve lofting for any given valve spring strength).
Much preferred are the positive type stem seals, which are made of either Teflon or Viton. The downside of these seals, is that their installation requires machining of the valve stem bosses in order to enable retrofitting.

[Joe L.]

Re: Valve spring/retainer question

If you have original type o-ring seals, then you only need the shields if you are not using the "umbrella" seals as well as the o-rings.
It is wise to eliminate the metal shields in favor of the "umbrellas" so as to reduce inertial weight on the valve side of the rocker arms. This reduction goes a long way in enhancing valve control (i.e: minimizing valve seat bounce and valve lofting for any given valve spring strength).
Much preferred are the positive type stem seals, which are made of either Teflon or Viton. The downside of these seals, is that their installation requires machining of the valve stem bosses in order to enable retrofitting.

Joe-----


The Viton type positive seals usually do not require valve guide machining.

[Joe C.]

Re: Valve spring/retainer question

Joe-----


The Viton type positive seals usually do not require valve guide machining.

Almost all of the Teflon as well as Viton positive stop seals that I have seen are either for a .494, .500 or .530 valve stem boss diameter. There may be some that will stretch to fit unmodified, pre-LS series engines which all have .560" diameter stem bosses.

[Joe C.]

Re: Valve spring/retainer question

I've been having some problems with components in the valve train on my L84. The engine was supposedly rebuilt close to stock, with an aftermarket version of the 097 cam. Since I know only enough about the subject to be dangerous, I've been reading up in the archives and elsewhere on line, to try and gain a better idea of what might be causing the problems.

I found two issues I'm concerned about. They might be critical, or, of little importance, I haven't got any idea:

The first, is about the spring retainer: I read that "the retainer must fit tightly into the spring". Mine are very loose. Does that really matter? If so, what problems do ill fitting retainers cause and how do i find proper ones?

The second: The valve springs in my engine are of unknown origin, They are similar in free height, but almost 50% stronger than new Sealed Power VS-677 springs (that are supposedly identical to the originals in the L84 engine) that I had tested.

Can pulled rocker studs (and a broken push-rod after the studs were screwed in) be caused by either of these issues?

Thanks, Mike

The retainers must fit tightly to the springs, and the locks (keys/keepers) must be compatible with the retainers. Generally, for stock or mildly modified (hot street/mild race) 7 degree keys/retainers are used. 10 degree keys/retainers are used with more exotic setups. Finally, both of these items must be matched to the OD of your valve stems, which is 11/32". If you are using stock replacement springs, like VS-677, then they should be installed at 1.7" height (valve closed). There are keepers/retainers available that can allow extra installed height when using a standard length valve stem, without any additional machining of the spring pockets................ I bring up all of this, just to show you how many variations of each component are possible. It is wise that you verify each item, and install only compatible components. Any mismatch is sure fire disaster!

For your application, valve springs need not have any higher rate than stock because the mild, gentle cam you are using does not require it. Of primary concern is to use a light weight spring which provides no more force than is necessary both on the seat or over the nose. Too much seat force causes excessive seat recession, insufficient force causes power robbing seat bounce. Excessive over the nose force causes pulled valve spring studs, worn lifters and cam lobes, insufficient force causes valve lofting. Additionally, excessive spring force causes excessive heat.

Pulled valve spring studs are a very real possibility if you use springs that are less compliant than the original or stock replacements. Spring pressure @ installed height of 1.70" should be about 80 pounds, @ 1.25" it should be about 200 pounds. Spring rate for your springs is 267 pounds/inch with coil bind @ 1.15", which gives you a SAFE max valve lift of .450" (using a .100" safety margin).

Here is a video of a valve spring system at high speed. Now imagine the result of a loose fitting spring retainer:

http://www.youtube.com/watch?v=_REQ1PUM0rY

[Michael G.]

Re: Valve spring/retainer question

Here's where I am with this today:

I bought VS677 springs and had them tested at 1.700 installed height. They only exerted 65 lbs of pressure at that height, plus, my current retainers also fit very loosely into them. I also measured the coil bind on the VS677's, it was at 1.10. Given the low numbers, I decided to get some of the EXPENSIVE 3735381 GM original springs, for comparison purposes, along with EXPENSIVE original retainers, which hopefully will fit better. Those will be in later this week.

The valves themselves seem fine. They currently have positive-type seals, move freely, and seat well.

When the parts arrive, I'll have the OEM springs measured; we'll see if they are closer to 80-90 lbs and if OEM retainers fit well into them. If they are good, maybe it'll be back together next week.

I can't drive the thing in all this snow anyway, so I guess this is a good learning experience. If I'm bored waiting for the parts, next I'll take my new LS9 apart, to see how IT works.

Mike

[Joe L.]

Re: Valve spring/retainer question

Almost all of the Teflon as well as Viton positive stop seals that I have seen are either for a .494, .500 or .530 valve stem boss diameter. There may be some that will stretch to fit unmodified, pre-LS series engines which all have .560" diameter stem bosses.

Joe------


Viton positive seals (GM #460483) were used on all 1981-91 Corvette small blocks and, as far as I know, all other 1981-91+ small blocks. I believe these same seals can be used on pre-81 small blocks without the need for valve guide machining.

[Joe C.]

Re: Valve spring/retainer question

Joe------


Viton positive seals (GM #460483) were used on all 1981-91 Corvette small blocks and, as far as I know, all other 1981-91+ small blocks. I believe these same seals can be used on pre-81 small blocks without the need for valve guide machining.

Thanks Joe.