Loose Valve guides

[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.