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-   -   Why don't my valve seals fit? (http://www.hotrodders.com/forum/why-dont-my-valve-seals-fit-150772.html)

maxpower_454 01-04-2009 07:02 PM

Why don't my valve seals fit?
 
I am rebuilding a set of 461 double hump chevy heads and bought umbrella valve seals to put on. I went to install them and it turns out that they fit the valves but hit then the valve springs will not fit over them. They hit the damper. Any idea why? Did i get the wrong ones? These are for a 327 and I think that is the engine these originally came on.

enginejr 01-04-2009 09:16 PM

Are you using aftermarket springs? I would think so, the id of the spring will most likely be too small for stock seals. Umbrella seals are kinda crappy anyways. If they are black and rubbery they may be a universial taiwan design, worse comes to worse buy a good set, if they dont fit you have to run the o rings or have them machined for positive seals.

4 Jaw Chuck 01-04-2009 11:08 PM

Toss the dampeners, they are next to useless and needlessly heat the oil.

maxpower_454 01-05-2009 08:57 AM

Can I take the dampers out of the springs I bought or do I need to buy new springs without dampers?

Jmark 01-05-2009 09:18 AM

Quote:

Originally Posted by 4 Jaw Chuck
Toss the dampeners, they are next to useless and needlessly heat the oil.

I think that answers your question.

maxpower_454 01-05-2009 01:33 PM

Quote:

Originally Posted by Jmark
I think that answers your question.

Not really........ Can I take them out or do I need different springs? Either way, i am 'tossing the dampers'.

oldbogie 01-05-2009 04:21 PM

Quote:

Originally Posted by maxpower_454
I am rebuilding a set of 461 double hump chevy heads and bought umbrella valve seals to put on. I went to install them and it turns out that they fit the valves but hit then the valve springs will not fit over them. They hit the damper. Any idea why? Did i get the wrong ones? These are for a 327 and I think that is the engine these originally came on.

Not an unusual problem, I'd keep the dampers they do a decent job of calming the spring's harmonics. The usual process is to trim the umbrella seal till it fits inside the spring assembly. They aren't really seals in the sense of Perfect Circle Teflon seals in that they never prevent oil from entering the stem to guide clearance. All an umbrella seal ever does is to redirect oil off the stem so that the stem/guide interface isn't swimming in oil. Many Chevy engines just use an O ring that rides on the stem, how's that for a minimalist approach.

The biggest oiling problem is on the intakes since the bottom of the stem/guide is in the intake and is subjected to manifold vacuum which tends to pull oil down the guide. So keeping the intakes dryer is the problem.

You should have really put positive seals on there which requires machining the top of the guide for installation. They are really the only effective way of controlling oil in the stem/guide interface, umbrella seals and O rings are not all that effective, they just meet the production requirement of cheap and generally last long enough to get the engine to the end of the warranty period.

Bogie

4 Jaw Chuck 01-05-2009 11:37 PM

Quote:

Originally Posted by maxpower_454
Can I take the dampers out of the springs I bought or do I need to buy new springs without dampers?

They just pull out, they might be tight since they are a spring...and new.

I never cared for them since they are not that effective and unless you are at valve float harmonic speeds don't really add life to the spring in my experience. I know the factory put them in but how many new engines do you see with them now?

None.

Spring wire technology has come a long way from the old days and the new steels they use to make springs don't have the problems the old steels did with handling harmonic vibration. However they do heat the oil a lot and shed metal particles into the oil which is never good, I think they cause more harm than good IMO.

I've always thrown them away. ;)

maxpower_454 01-06-2009 06:58 AM

I've thought about machining the guides for positive seals since it looked like it can be accomplished with a special tool and a drill by looking at the crane cams directions but I cannot find a cutter or anyone who has actually done this. Is it easy or is it machine shop worthy? If i can do it, i may buy a tool, otherwise i think i'm sticking with the crappy umbrella seals.

jimfulco 01-06-2009 08:32 PM

I strongly suspect that if the dampers were not necessary, the manufacturers would not have spent millions of dollars putting them on virtually every engine they produced for I don't know how many years.

oldbogie 01-06-2009 09:06 PM

Quote:

Originally Posted by jimfulco
I strongly suspect that if the dampers were not necessary, the manufacturers would not have spent millions of dollars putting them on virtually every engine they produced for I don't know how many years.

I concur, if anyone had any idea how cheap Detroit is, they'd know for certain that if an engineering device is included, its been tested for effectiveness and is found to be necessary.

The fact that people take a modified engine beyond where such devices are designed to go and then make pronouncements that these things aren't effective are missing the point that inside the design requirements established by the manufacturer, they do what they're intended to or else the Finance and Design to Cost people would make double dam sure they weren't there.

The subject of new spring materials has also come up. Well if you're using ovate section wire made from un-obtainium, wound in the beehive pattern and with differential rates of coil spacing, then they don't necessarily need gadgets to reduce rate harmonics. But if the thing is using round wire sections made from tool steel, with constant rate diameters and coil spacing, then this ain't the rocket science stuff and you've got to fall back on the old tried and true methods to dampen rate harmonics out of the spring.

The originator of this thread needs to realize that if he goes where the spring can't control it's harmonic reactions, the cost liability when a piston meets a bouncing or trailing valve is going to far exceed the cost of sucking a little oil down the guide.

Bogie

4 Jaw Chuck 01-06-2009 11:09 PM

Crane Cams Article-Valve Spring Resonance: What it is and how it can be controlled!

Best description I could find that describes the function and application of the valve spring coil dampener. Here is the only advantage of the flat wound spring dampener as described in the article;

"One real plus of a damper used with a (single) coil spring is that if the spring should break, the damper acts as a safety to keep pressure on the retainer/lock package to prevent dropping the valve into the cylinder."

Kind of explains why they started using them on very early engines with poor quality spring wire, they would occasionally break and this was a safety device. Most engines today (except for heavy duty diesels) don't use them as the engine speed is never constant and loads on the engine isn't high enough which could cause spring surge situations.

techinspector1 01-06-2009 11:16 PM

Interesting arguments from both sides. Thank you.

oldbogie 01-07-2009 10:28 AM

Quote:

Originally Posted by 4 Jaw Chuck
Crane Cams Article-Valve Spring Resonance: What it is and how it can be controlled!

Best description I could find that describes the function and application of the valve spring coil dampener. Here is the only advantage of the flat wound spring dampener as described in the article;

"One real plus of a damper used with a (single) coil spring is that if the spring should break, the damper acts as a safety to keep pressure on the retainer/lock package to prevent dropping the valve into the cylinder."

Kind of explains why they started using them on very early engines with poor quality spring wire, they would occasionally break and this was a safety device. Most engines today (except for heavy duty diesels) don't use them as the engine speed is never constant and loads on the engine isn't high enough which could cause spring surge situations.

People give lots of goofy reasons why engineers do things, in this case the flat wound damper is there for one purpose as its name implies.

It is a damper, it uses friction between itself and the spring, which is why it always has physical contact with the spring wire. It works in exactly the same way as friction shock absorber did back when they were used on suspension systems rather than contemporary hydraulic tubes. The friction between the elements disrupts the harmonic response of the spring which has nothing to do with being made from poorer or better materials. All springs have a harmonic response or beat frequency. For the valve train the beat frequency or some resonant of it would be hit when the actuation rate based on engine speed happens to coincide the springs natural frequency. The damper coil is put there to change the springs natural frequency, which was usually found by test but today more commonly by digital analysis, to be within the operating range of the engine. Such frequency responses in the spring are simply the result of high RPM operation of the engine, these frequencies and their resonant responses can occur anywhere within an engine's operating RPM range. The masses of the valve, keeper, locks, rocker, pushrod, and lifter also affect the harmonic response of the spring. So does the dynamics of the cam lobe, its shape, timing, and lift.

So the flat wound damper is a simple device that changes the spring's natural frequency so that it doesn't develop harmonic responses within the anticipated operating range of the engine's valve train. Changes to the afore mentioned components and the engine's operating RPM range will change the installed springs harmonic response.

For the average engine builder, this extent of engineering analysis required to understand spring harmonic response is simply beyond their capabilities, if they even understand this stuff exists. We, therefore, are dependent upon the cam manufacturer's recommendations as to which springs to use. Unfortunately, many people choose this as a place to save money when buying a cam which often gets them into a lot of trouble. Needless to say the professional race engine builders spend a lot of time on this as the average solution used for street and occasional race engines of stiffer and stiffer springs is an insufficient solution for guys who earn their living racing.

I suppose dampers could be a last ditch device to prevent a valve from dropping too far if a spring broke, but usually when a coil breaks the valve only drops the distance of the coil to coil clearance of one coil, which usually is not far enough into the cylinder to interfere with the piston. Although I'll give it that in really high strung engine's I've seen springs practically disintegrate, but on the street or with the occasional racer such incidents are rather rare.

Bogie

techron 01-07-2009 11:19 AM

i agree with every one of bogie's posts. the damper spring is called a damper for one reason--it dampens the harmonics of the spring!!! uncontrolled harmonics can kill a springs life. as far as the damper being there to keep from dropping a valve, i don't buy that. as bogie said--i have replaced broken springs over the years (usually on BBCs) and in every case it's one break where the upper coil just rests on the next lower coil, BUT the spring is still rests solidly aginst the head and still holds the valve shut sitting solidly aginst the retainer. the damper spring is there to dampen harmonics of the spring, the damper is an inteference fit inside the spring and rubs aginst the spring-dampening it (check the fit of a spring and damper off the engine)

maxpower, i have had one of those guide cutter tools in my box for decades. yes, they can be used with just a drill. the guide goes in the valve stem hole and keeps the cutter centered, it works great, i have used it many times... :thumbup:


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