Broken valve spring

[jimynick]

Excuse my ignorance.......all new to me.....So that is the distance between coils when the valve is completely open or when it is being compressed open?

So just making sure there is clearance around the spring where it seats , yes?   I can say that the broken spring rotates around really easily (all of the spring parts, not just half, etc)

I did a compression check on all cylinders.....all around what they were when I did the last couple checks over the years as I recall...I had posted the results here on the forum, gonna see if I can find those numbers.......


This reading --

cyl       reading

1           133
 2          127
3            dead
4            140
5            138
6             141
7            130
8            144

Yes, it's the distance between the coils when the valve is completely open and the other is the distance from the bottom edge of the retainer to the top of the valve guide. Check the comp on that cylinder when you get your new set of springs in, as, if the valve dinged a piston, it may have bent enough to lose it's seal.

[Chryco Psycho]

I used a lot of Comp due to accessability but there are better available , often bought kits with cam lifters & springs all matched

[shadango]

I like the Valve spring tool from Mancini , use air pressure or nylon rope in the cylinder to hold the valve closed & bolt the tool to the rocker pedestals & it levers down on the top of the retainer , easy to use . With a dial indicator you can measure the cam lift & maybe determine what cam you have , I would use a slightly overkill spring than something marginal for spring pressure , Lunati cams have a fast ramp & require more pressure even for the same lift to keep the valve train stable , it is possible that the spring hit a harmonic or could not keep the valve train tight & bounced causing the failure .

Thanks !   I have the tool to use air pressure....what pressure do you suggest? I read elsewhere about 40 psi?  I have a tool that is supposed to do the job on the spring.....it has two sets of "forks" and a star wheel at the other end that as you turn expands or contracts....



For measuring cam lift , I guess set up the dial indicator on the top surface of a rocker and rotate the engine thru a cycle?  Could I measure using the push-rod after the rocker arms are off (they are off now)......?  I guess I could just as easily pull the passenger side rocker cover and measure there once I get a dial indicator.  I do not have a dial indicator yet....gonna try and see if I can pick one up at harbor freight.

When I go to put the rockers back on I assume it is best to have the engine at a point where all the valves are more or less closed so I am not having to fight the valves, right?

My plan is to pull the broken exhaust spring to check for any numbers etc. first..... Then maybe the exhaust valve of a neighboring cylinder to measure for uncompressed height.

As an aside, I have another tool I am wondering "WTF is it?"

[Chryco Psycho]

I have used full compressor pressure so 120 psi , the cylinder will make that much anyway . I have often measured cam lift off the end of a pushrod using a small 1/4 inch drive socket to keep the gauge lined up , you will alwys have 1-3 valve open when the rockers go back on , I use a piece of rod like a coat hanger along the rocker pedestals to hold the pushrods up as I tighten down the rockers . the other tool also looks like a compressor tool from the side though must have a specific application

[tommyg29]

Seen that tool to work a different ohv setup. You wont need it.
Now, is it necessary to use compressed air (or rope) if you know a piston is at TDC.
The valve wont fall far
Too bad theres not an easier way or tool to hold it from the top, but obviously no way to grasp the stem while actually sliding the spring off.
I think I would invent a slightly different keep system.
Make the hole in the retainer slightly bigger, and make the keeper fatter/wider to cover the larger hole, so that when you remove the keeper, you could put another smaller clip of some kind onto the stem that would fit through the bigger hole and prevent the stem from sliding all the way down. Of course, the compressor tool would also have to have something to clamp onto the very top of the stem to hold it up while you are switching keepers.
I bet someone has a tool like that already.
By the way, are you planning on swapping your seals and your "aluminum" retainers.

PS
I read somewhere that you can also hold up the stems with a wood clothespin if you have to step away for any length of time in the middle of a job, so it might be a good idea to keep one of them or maybe soft jaw vice grips. Never know

[Strawdawg]

I used a lot of Comp due to accessability but there are better available , often bought kits with cam lifters & springs all matched

I asked because I have noticed a lot of the ligher Comp springs seem to vary quite a bit when I checked the open height pressures in the past few years.

I installed a Lunati Voodoo a couple of years ago when replacing a purple Mopar but did not do the springs as the car was not being driven at the time...getting close to that now so this thread made me think about springs.  I see the Lunati 74820's appear to be a beehive design and thought I might try them (for a 440)

[shadango]

My dad-in-law came over and we got the spring off. Not hard, but the keeper was in there good!   A little tapping and we were Ok.

Doing some measurements, seems like they are the mopar P4120249 springs, so going to order a set of those.

The plan is to install the one spring and then check for compression.......the valve seems fine, and spins freely in the seat, but you can hear some air getting through somewhere in there.....and the air leaks down if not kept pumped up. My dad says that it is probably because the air pressure isnt enough to really close the valve 100%, that the spring would have much more closing force than the air....praying it isnt a cracked/broken piston, but I will know for sure after installing the spring.

In the meantime, we used a piece of hose on the end of the valve stem to keep it held up, as well as a vice grip with jaws wrapped with duct tape just gently holding as well.

The valve seal (black cup looking thing)  came off with the spring......it is not "brittle" but is is harder/less flexible than I figured it would be........should I change out the seals while I am there? Wasn't burning oil before but, for $17 at summit, they are cheap insurance I guess.....

The retainers appear to be the titanium ones that Mopar Performance sells.....they sell two types --- CrMo and titanium. No aluminum ones.  So I think I am safe with what I have.  i also noticed a shim under the spring when I took it off....I am leaving those as is I think.   Installed height on the neighboring valve I checked appeared right (1.70).....wire diameter seems the same (.206)....

[burdar]

The MP springs in my 360 look just like yours...red single spring with damper.

[brads70]

When I've changed valve springs I insert a chunk of nylon rope in the spark plug hole and wind the cylinder to the top just in case it were to fall down it wouldn't go far. 

[jimynick]

That strange looking tool IS a valve spring compressor, BUT the one I have, was used by my old man on the side valve flat Dodge 6's of the 40's and 50's. I think you could also use it on flat Fords. There, that's your piece of useless trivia for the day. Good luck with the valve. There are a variety of viewing devices (glorified bore scopes) that will fit in the plug hole and have their own lights in the end and you can actually turn them to look  all around if you suspect piston damage. This can be done w/o removing the head. 

[shadango]

I do have a borescope of sorts.....long flexible shaft with video camera at end, but the head is too large for spark plug holes.....   

I am going to try and see if I can find a rental somewhere, maybe.

[tommyg29]

the cheapo USB connection borescopes can be used to look through the plug hole but like yours mine doesnt fit either. All you can see is maybe a very small portion of the piston. Cool to play with though and can be very useful. For $30 they are handy to have around.
Saved me one time from having to pull the top of my stealth motor since I was able to confirm I did NOT drop a nut down one of the runners

[Chryco Psycho]

even using a light in the cylinder & looking into the exhaust & intake port you may have a clue if the valve is bent , I assume it has to be bent as even with the broken spring it should have closed the valve enough to get some compression

[shadango]

even using a light in the cylinder & looking into the exhaust & intake port you may have a clue if the valve is bent , I assume it has to be bent as even with the broken spring it should have closed the valve enough to get some compression

Just to clarify -- with the (broken) spring in place and the air compressor on it, I do get some 'compression'.....it seals up enough to create enough pressure where you have to push fairly hard on the valve to release it.

What happens is that when I turn off the compressor it leaks down without the spring on it.  I used a piece of rubber hose on the end of the stem to hold it in place......and a pair of vice grips with tape wrapped around the jaws GENTLY adding some hold to it as well.

When I manually moved the valve up and down it seemed fine.....it would be tight if it were bent, wouldnt it?  It also could be turned smoothly with the valve seated......

I ordered new springs and seals, going to do the one spring and do a compression test.

I can see down into the bore thru the plug hole some and my video scope shows me a little of the piston and what I can see looks OK......praying for the best.

[Chryco Psycho]

A bent valve will bend below the stem so it will still slide up& down Ok but yes the compressed air will leak past the gaps in the rings & bleed out so you should be Ok