Loose Valve guides

[B_man_Al]

Has any one ever seen the valve guides coming loose on an 8BA engine before? The engine has less than 10 hrs (none on the road, except around the neighborhood) and two of the exhaust valves have come loose ( 7 & 4). I thought it was sticking valves at first, but looking at it closer, the entire assembly is moving up and down ( valve, spring and guide). I haven't taken off the intake yet but I can see them moving through the fuel pump hole.

I can't imagine the C clips coming loose, considering how difficult they are to get in in the first place.

Anything that can go wrong does!

Al

[billwill]

That thataii that could happen

[rotorwrench]

The valve springs usually hold sufficient pressure on the clip to keep it from coming out. I have seen the cast iron guides crack and chip bits of the groove edge that holds the horse shoe clip in place though. Maybe the edge broke off of them for some reason. Maybe they got accidentaly dropped and hit there causing cracks that gave way. Sh!t does happen.

[B_man_Al]

It turns out that the problem is indeed stuck valves in the guides on both. While it looked like the C clips had come loose, after taking the intake off, they hadn't. They are still holding the valves, springs and keepers together, but because the springs are compressed and jammed there, the guide is now free to move up and down in the block, appearing as though the whole thing had come apart. Good news as far as fixing, but now to find out how to prevent more of them from seizing on the valve stems. Some kind of top lube I guess until they get a little wear on the guides.

[Mart]

I have one motor where the horseshoe clips were inserted between the end of the spring and the guide. Heaven knows what would have happened if it had been fired and ran.

Mart.

[Ol' Ron]

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More than once I thought I had the horseshoe clip in place, but had it under over the spring and not in the grove..

[rotorwrench]

Stainless steel stem valves sometimes gall in the cast iron causing problems. If it's just carbon, the guides can be polished. If the valves are all stainless and galled, a phosphor bronze sleeve in the guides would keep any further galling from happening. So many of the new repro parts are stainless now but I don't know if the stems are or not. A magnet would tell for sure.

Could still just be the clip not properly in the groove.

[jimTN]

Sounds like defective guides!

[Ross6860]

Originally Posted by rotorwrench

Stainless steel stem valves sometimes gall in the cast iron causing problems. If it's just carbon, the guides can be polished. If the valves are all stainless and galled, a phosphor bronze sleeve in the guides would keep any further galling from happening. So many of the new repro parts are stainless now but I don't know if the stems are or not. A magnet would tell for sure.

Could still just be the clip not properly in the groove.

Not all stainless is non-magnetic. No idea exactly who is using what grade to make valves.

Anyone know?

As far as helping the valves out. Marvel Mystery Oil and SeaFoam.

[rotorwrench]

This is true but the ones that are are generally the type that have to have some cold work done on them to get the magnetic properties back slightly like cold rolled types 301, 302, & 304 but all are non magnetic in their annealed states.

[oldford2]

It turns out that the problem is indeed stuck valves in the guides on both. While it looked like the C clips had come loose, after taking the intake off, they hadn't. They are still holding the valves, springs and keepers together, but because the springs are compressed and jammed there, the guide is now free to move up and down in the block, appearing as though the whole thing had come apart. Good news as far as fixing, but now to find out how to prevent more of them from seizing on the valve stems. Some kind of top lube I guess until they get a little wear on the guides

So what happened to the horseshoe clips??

[rotorwrench]

The only way it can come loose in the bore is if it shears edges of the clips out. If it did, that would be preferable to a broken camshaft or a messed up hollow cam follower. I've seen the valve stems go right through the OEM non-adjustable followers before. The valve guide bores might be a bit loose now. Might have to glue them in.

[Karl Wolf]

I knurl new guides, then clean them out real well with solvent and a brush on a drill motor.
Knurling puts a threaded-like finish on the inside of the guide. Makes it a lot less likely to seize. This also resizes the guide to fit the valve stem.
Years ago I bought some copper plated (on the outside) guides from Reds Headers. This was to make up for a loose fit guide to block. If you decide to use a glue like product, be aware that one of the things exhaust guides need to do- transfer heat. And, I would put in the valve assembly with the guide to make sure that the valve is centering the guide where it needs to so the valve will seat.
Karl

[GEOFFNZ]

I had an engine where two valves froze in the guides and broke the bottom out of the retainer slot in the guide the bits of which were in the bottom of the valley. The C clips were still in place but the guide was going up and down with the valve. Must have been big stress on timing gears etc.

[B_man_Al]

Oldfor2 ...

The C clips are still there, but can be easily removed by hand as the guide and valve assembly is now "shorter" since the spring is seized in the compressed state.

Rotorwrench ...

Similarly,as the springs and valves are stuck compressed, the guide is free to move up and down in the bore.

This raises an interesting point, though, about measuring the gap. In order to get an accurate gap setting, the guide must be fully pushed up against the C clip and recessed in the block. When the cam pushes the assembly upwards, the guide will bottom on the clip, but if it is loose in the guide bore, it could slide down by the amount of the gap when the cam is rotated by 180 degrees from the max lift position, appearing as though there is no gap. Under this condition, the C clips will be loose, but cannot come out because of the recess in the block.

[GOSFAST]

Let me put this up here again, it won't help "already-built" units but it may help on future builds.

Install bronze liners in the guides, we started this program/procedure many years ago and to this day haven't had one single "stuck" valve!!

There are numerous reasons for this happening, the valves hanging, but most times it is moisture inside that doesn't "burn" off. It accumulates in the system especially after driving short trips and shutting down. Having owned numerous Flatheads over the years and driven miminal numbers daily (under 1 mile to the shop) this was always an issue with the exhaust systems also. Constantly replaced pipes and mufflers.

For the cost of the bronze installation, which initially may be somewhere around 8.00/9.00 per guide, it's really good insurance in the long run, just in the price of gaskets alone, not mentioning the labor involved. If your original guides are OK you just "line" and reuse them.

While knurling guides is OK, it doesn't "change" the materials involved. There is more "resistance" with the bronze liners to moisture collecting on the stems than with the cast iron guides/steel valves. You can also run slightly tighter valve-to-guide clearance in there. We do not "ream" bronze liners, they are ball-broached for sizing. Some get finished with a Sunnen valve guide hone also, not to be confused with the silicon ball-type hones, it uses actual stones and guides get I.D. measured with a bore gauge. About 99% are fine with the ball-broach setup.

Thanks, Gary in N.Y.

P.S. We would never reuse the original guide retainers (horseshoe clips) anymore, always use new pieces. I would also use some Viton stem-seals on the guides.

[B_man_Al]

Just to clarify my stuck valve problem, 2 pictures showing the movement in the valve assembly with the stuck spring. Note how far out of thebore the guide will come in the down position.

[Binx]

Since this is a new build is it possible the valves hit the head, bent the stems and jammed in the guides?

Lonnie

[B_man_Al]

Binx ...

I hope not but I don't think so as the exhaust valve would have hit the plug before the head I think. The plugs are OK

[Mart]

I suppose this is an odd situation because the engine is low miles. From my experience, this would not happen on an older motor because the guide is tight enough in the bore to not move. Most of my problems have been from guides not wanting to move in the bore. I've never had them moving when I didn't want them to!

If you can free them off and use something to add lube to the fuel as you say it will probably be all right once it gets some miles on it.

Mart.

[rotorwrench]

Originally Posted by B_man_Al

Just to clarify my stuck valve problem, 2 pictures showing the movement in the valve assembly with the stuck spring. Note how far out of thebore the guide will come in the down position.

Now I see what you are relating. Generally I'm dealing with motors that have not had an overhaul in many years so the guides are pretty well frozen in their bores but since yours is a recent overhaul, the guides can still easily move in their bores. I've generally noted that guides aren't all that close a clearance with the valves stems even with new parts. The phosphor bronze sleeves may be the best choice as Gofast mentioned. They are softer material for one and will not corrode for the other. When I was a kid up in Kansas, we had no problems with sticking valves but it was more than a few miles we generally had to drive and the relitive humidity average on the high plains is about 25% so it wasn't a problem there. Only the old folks that drove to church on Sunday & the post office every day had gunked up engines. They never even got warmed up. On the farm, they got warmed to peak temps every time we drove them.

If the valve to head clearance was checked during overhaul, I doubt if they hit the head unless there was a carbon build up or something

[B_man_Al]

I don't know if this is coincidence or not, but the two exhaust valves (7 & 4) which seized are on the same barrel of the carb . I wonder if one barrel is running too lean and causing excessive heat. The car is however overall running very cool, with lots of vac advance ... approx 15 degrees at idle with a modified GM distributor connected to manifold vacuum.

[Mike51Merc]

Kind of strange for a valve to bind up in a guide like that, especially on a fresh rebuild.

Oil starvation? Tolerance too tight? Bent valves? I can't imagine they're gummed up or carbonized already.

Let us know what you find when you disassemble valves.

[ThomasN]

I hope you used new gas. I have a friend that runs a cylinder head shop and some of his repair work is due to using old ethonol fuel and freezing up the valve guides and actually bending push rods in oh engines.

[JWL]

I am left wondering how much spring pressure there is when the valves are on seat? Those look like good LZ type springs which should be relatively easy to set at 50 lbs. Not enough spring pressure can contribute to the problem you are dealing with. Idling at low speeds before the engine is "broken in" can also be a factor.

[ford3]

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put 4 to 6 oz of marvel mystery oil in every 10 gallons of gas, its an exlnt intake valve lubricant, with this new alcohol fuel i would use the 6 oz ratio

[B_man_Al]

JWL ...

What do you mean "set the pressure at 50 lbs"? You get what you get don't you?

I got #4 free this afternoon by making a 3/4x 3/8 x 2 1/2" hardwood stick to put between the handle of the C clip and the lifter boss to hold it up while tapping on the valve through the plug hole. After a few trys, and some penetrating oil, it is no longer sticking. I can see either rust or carbon on the valve stem below the guide where it was stuck.

I suspect the 2nd one will be the same.

Looks like a lack of lubrication. The valves were put in by the machine shop back in 2006, but I'm only just getting it running this year!

[Karl Wolf]

I use valve spring shims. They go between the guide and the spring... With this, one can determine the size of the space the spring is held in- in the closed position, and thereby the seat pressure.
Karl

[B_man_Al]

Karl/JWL ...

Your replies have me thinking about my other valves, and if they are also stuck, or if there is something else wrong. The reason is that the C clips on several valves are not tight, and although you can't get them out, they do not have much, if any spring pressure on them, holding the valve closed on the seat.

So the question then becomes, with a fully assembled valve, spring and guide inserted into the block, how far into the bore is the c clip groove beyond the face of the bore?

To put it another way, typically how much does the spring need to be compressed to allow the guide to move down enough, in the bore, to get the C clip in.

Also , are the springs for the rotator assemblies the same lengths as the fixed ones? Maybe I have springs which are too short?

[JWL]

With a valve closed, and clearance at the tappet, precisely measure the length of a spring. Something in 2 to 2 1/16" range should be about right if the springs are good.

Yes there are different length springs for the rotators but based on my interpretation of your pictures the springs are correct type.

[B_man_Al]

Looks like the springs are OK. They measure about 2 1/16 to 2 3/16 in the closed position. I checked an old uncompressed spring .... it measures 2 7/16 so the installed ones are compressed at least 1/4" .

[JWL]

There can be a significant variance in seat pressure between 2" and 2 3/16". It is "normal" to set spring lengths to within .015 or less depending on the application. In many examples each spring is measured at the desired level of pressure and custom shim installations are made to maintain that pressure without regard for equal heights. I don't feel such discrimination is necessary for a daily driver but I do think each spring should be checked and verified to provide reasonably close pressure at a given height.

[GOSFAST]

Just to add to the above info, one area to watch closely for when "shimming" valve springs is the height of the "register" where the spring rests.

There isn't really enough room to get too many shims down there and have enough register left to keep the spring stable. That area would most likely be "used-up" by a single .030" and a single .060" combined, and not have enough register remaining for the spring.

When you lay-out the program on the new build it's nice to use a spring that will work with minimum shims.

(Add) If working with a "progressive-wound" spring make certain the "stacked" ends rest directly against the guide or the shim. (See the photo below)

(Add-2) I would be very reluctant to reuse the guide retainers (horseshoe-clips), new are not all that expensive. Most old ones I've had in here are in "sad" shape for the most part.

Thanks, Gary in N.Y.

P.S. Every .030" decrease in the installed spring height would raise the pressure roughly 5#. If you have 50# on the seat and were to add a single .030" shim you will see 55#. A single .060" would equal a 10# increase.

[Karl Wolf]

Put a bathroom scale under your drill press, or use a c-clamp, or any other creative combination of things...
Put a valve spring on the scale and make it go to 50lb- my favorite seat pressure. Measure the spring height, and reproduce this measurement in your valve installation.

Keeping in mind Gosfast's advice. About the place on the guide that centers the spring.
And, like JWL, I like the springs installed height to be almost identical.

I like the Lincoln Zephyr-like springs I've bought from Reds Headers, along with
one(per) .060 Hastings valve spring shim seems to have worked for me...

In a 59AB, Chev exhaust valves, Schneider regrind cam.
Karl

[B_man_Al]

In the end the stuck valve turned out just to be either carbon or rust build up in the guide. I got a .342 and a .343 reamer to clean them out (intake and exhaust respectively). Any ideas on the best pre lube to put on the stems and guides during assembly? Its likely to sit again for prolonged periods of time.

OPtions:

engine oil
MMO
STP
graphite
hi temp brake grease

The valve spring pressures were measured at 3 points 2.125, 2.0, and 1.83. Averages came out at 37.5,

[B_man_Al]

Hit the send button too fast.

The valve spring pressures were measured at 3 points 2.125, 2.0, and 1.83. Averages came out at 37.5, 51, and 69 respectively. Variation was 36 to 40 at 2.125.