Why did I break valve springs??

I was at the track last night and the wagon was running slow. Lately, it's been pretty consistent, running 11.80-90's in the heat. Last night, the first pass netted a 12.16 with mph down almost 3 mph at 107. I figured that's fine, usually the first pass is a cleanout pass especially since I had driven the car several times in the last week.

But then on the 2nd pass the car ran a 12.25 at 106 and it felt like someone lowered the rev limiter as the engine had a minor vibration beginning at ~5000rpm. At the top of each it was like the rev limiter was coming on or the valves were floating. Checked the ignition box settings and some of the basic stuff - everything looked fine.

For first round I had the bye - car ran a 12.28 at 106, feeling just as it had the run before. Naturally, I wouldn't have minded losing 1st round because the car was off, but as it always goes, the rounds kept coming as the car kept getting slower and slower. It wasn't making any funny noises or popping or stumbling, had plenty of oil pressure - just the roughness above 5000rpm, well besides being down on power. So, 5 rounds later I'm in the semi-finals, pull through the water and spin the tires, engage the line lock and begin to bring the rev's up to do the burnout. At about 3500rpm the motor just quits. Turn it over again and it spins freely and smoothly, pops a little as if it's going to fire but nothing. Try one more time so I can at least stage it to get my points for the round, but nothing.

Put it on the trailer and take it home. First thing I do is pull the dist. cap and turn the engine over. The rotor spins with the motor - no problem there. Then I pull the plugs - a couple of them look a little dark compared to the rest but nothing really out of the ordinary. So I pull the valve covers to check rockers, pushrods and valvetrain. That's when I discover 3 broken valve springs - 2 intakes, 1 exhaust, all on the driver's side, cylinders #1,3 & 5. All broken near the base on the outer spring (these are dual spring).

The springs are older springs I got from Torque Tech and they were shimmed to give me 125# closed and 300# open. The heads are untouched cast iron stage 1's - I'm using these while I save some money for the aluminum ones.

What would have caused the breakage and why only on the driver's side?? Do you think they were just plain worn out; hence the reason for the shims? Do you think is the only reason the engine was running rough? What else should I look for in terms of other potential damage? I plan to pull the pushrods to check for straightness adn change the springs, but is there anything else I should check? As I said, there are no strange noises coming from the motor, while it was running or as it's just being turned over.

Thanks for any help!!

Paul

 

Are you running a single coil spring?
Or one with an inner spring or harmonic damper?

Looks like everything was set up right as far as coil bind etc. goes.

I broke a couple of springs in a Ford 400-M engine with very mild cam that had never been revved very high. Probably not over 4500 rpm. It was in a 3/4 Ton 4 x 4 and used for towing a sailboat.

I talked to Crower about it and the tech guy said, "if everything was set up right, sometimes springs just break. For no particular reason."
I stuck a set of Crower springs in it and no further problems.

It's been a few years since that little incident, but I'm pretty sure the stock Ford springs were single coil.

At higher rpm levels harmonics enter the picture and springs behave very erraticly.

I'd recommend you go to a double spring setup, an inner and outer coil or with a flat wound damper inside.
Preferably from a Buick oriented speed shop.

I have a set of Kenne Bell springs shimmed to the minimum pressures since my 2400# car doesn't get wound up very high rpm-wise - 4500-5000 rpm the max and not too often at that.

41,000 miles on the KB springs & other parts and still going strong.

 

The springs have the regular outer coil spring with an inner spring or dampener. How long do springs normally last? I probably should have mentioned that these springs are fairly old with maybe 35-40,000 miles and several hundred passes on them. I believe everything was set up correctly - right now I'm going on the theory that they were just old and tired.

Thanks for the comments. Any others?

Paul

 

BUmmer Paul.....we all know how hard you worked to get the wagon done.....hope you find the problem quikly and can continue your weekly points racing

The probability of just general failure causing one spring to break might be a valid conclusion.....

.....but the odds of 3 valve springs failing simultaniously - for no reason but fatigue - are pretty slim.

general Failure analysis and MTBF (mean time between failure) of parts do follow a bell curve (indicating like components have similar lifespans), but considering the number of cycles on those springs.....and for them to fail within such a short time of each other would lead me to look further.

As an example.....

I had my car once blow BOTH headlights simultaniously (of course while driving on a dark deserted road ).

If one headlight had blown, the obvious conclusion is "It just died from end of life failure".

But, the probability of BOTH lights failing at EXACTLY the same time from end of life failure is miniscule.

 

I'll bet one headlight failed first, then the sudden increase in voltage from the reduced load was just enought to push the other headlight over the edge soon (fraction of a second) after.

 

Hey Paul, I've got those valve springs for you. T/A 1125. should put you back in the 11.60's(or better) again. JEFF

 

It might be that you were driving for a while on one or two broken ones, but the third one was when things gave up the ghost.

- Freed

 

Freed, I was almost thinking the same thing. If they went one at a time over the course of several weeks or months, I really hadn't noticed. The only thing I have noticed is that the car hasn't run nearly as quick as it had about a month ago. I kind of blamed the poorer and poorer air but maybe the valve springs are to blame. There was a week where the car was consistently running 11.81's dipping into the 70's and 60's briefly. But the last couple of weeks, it was getting hard to even dip into the high 11.80's and that was pretty rare.

Jeff, thanks, I will be taking those valve springs off your hands! I'll be in touch.

Paul

 

Paul, sorry to hear about the problem....but (not to be the bearer of bad news) I don't see that some broken valve springs would shut the motor off....might not rev but should run. I would say something additional happened........

Bruce

 

Paul,

any update from last week ? Hope you found the trouble.

Tom

 

Here is a portion of a post I made a while back regarding my car in the "Who has a drop top" thread (around page 6)

...My brother on the other hand had his one and only chance to drive it. Borrowed it exactly one week after my purchase to go to a going away party for a friend of his joining the army. I foolishly let him take the car. He normally drove a welded and bondoed 70 Nova SS 350, 4 speed and 4:11 posi that would literarily stand on its a** and peal the hides. He was good at it also, too good as it turns out. The next day I start my car and it has a tapping sound. My father and I are in denial and we drive it to the local gas station to put some "leaded high test" gas in it thinking that was what it needed (lead for the valves? I don't know what we were thinking). About 0.5 miles from home, the tap turns into an all out rap. I keep driving, nursing it the rest of the drive home, park it and literally cry. After two days, I get my courage up and pull the left valve cover. I find a broken valve spring (in three places) that has completely collapsed, the keepers have fallen out, the rocker arm has slid on the shaft and the rapping was the pushrod hitting the valve cover. The valve is sitting right there in the seat. I can't believe my eyes and I can't believe the engine is in one piece. I buy a KD valve compression tool that uses air pressure through the spark plug hole and replace all the valve springs with new Stage 1 springs as well as replaced the bent push rod. The valve cover still has the visible scars. To this day I don't know why it didn't suck that valve into the engine! And to this day, my brother has never driven my car again! A few years later, a friend of his says to me, "you should have seen your brother grab 4 gears of rubber between the length of two telephone poles with your car." hmmmmmmmm, that explains a lot! ...

When I called the previous owner to ask him if he had ever had this problem, he had also replaced a broken valve spring and gave me a second set of heads he had picked up in a junk yard to get by until new springs could be ordered. I suspect I was responsible for the first break while giving a high rev the night before my brother probably gave the second break. These motors are so powerful, I suspect you could have a broken spring or two and not really know. The third break was likely when the loud rap sounded after the keepers fell out of the spring, the rocker arm slide and the push rod started hitting the valve cover.

Maybe your the shut down was caused by the disruption of the vacuum needed to draw the air full mixture through the carb and intake??? Just an optomistic theory!

 

As an update, I'm looking for suggestions now!!

I replaced all of the valve springs tonight and attempted to start it. It popped a couple of times but did not start. I only made one attempt before deciding to look elsewhere to make sure other things were not hurt.

In the course of replacing the valve springs, I had rotated the engine by hand to keep the piston at TDC on the cylinder I was working on. I noticed that as I lined up the #1 cylinder at TDC, I took a look at the position of the rotor in relation to the distributor cap. By eyeball it looked like the rotor was closer to the previous cylinder (#2) than it was to the #1. I'm used to seeing the rotor very close to the #1 terminal - it definitely was not. So I pulled the distributor and I knew something was up because it was difficult to get it out.

What I found was a distributor gear with several teeth practically gone all in one area. 75% of the gear looked good with a great wear pattern, but in one area, 2-3 teeth were knife-edged and worn down to stubs. From what I could tell, the cam gear looked to be in similar shape.

What's going on here??? Did the timing jump either at the cam-distributor gear or possibly at the timing chain? What the heck would cause that to happen? Or did something else occur? Whatever it was gave me no indication - everything has been running great - smooth, quiet, no funny noises. What should I be looking at now???

Paul

 

Paul

possible causes:

hi vol oil pump
pump set up too tight
oil too heavy
revving when oil is not up to temp
too much oil pressure in general (80 max)
incorrect tooth mesh
worn shaft hole on timing cover
improper breakin of cam/dist gears
cam walk
too much end play on dist

Mike Pollock just went thru the same deal with a couple teeth broken
The good news is after he fixed it (new,same type) he picked up ET....was losing cam/dist timing.

Bruce

 

Paul,

I have a nearly complete running 455 Buick Motor at my House,

let me know if you need something from it in a jam.

it will be going into my skylark, but not until next year.

Tom

 

Tom, thanks for the offer but I have a fairly substantial selection of pieces to choose from, stockpiled over many years. We'll talk at the track Wednesday.

Bruce, thanks for the suggestions. I'm trying to dismiss some of them for the simple reason that this motor has been together for almost 2 years now.

Going through the list above: I have never run a high volume pump, looking back thru notes - I set the pump up correctly in terms of clearances, I normally run a blend of 10w-30 & 10w-40 oil (I guess I don't consider that to be heavyweight, right?), I always warm the engine & the rest of the drivetrain up before making a pass, I've got the max. pressure adjusted to ~80-85psi when cold and this gives me roughly 70psi at 5500 when warm, I assumed the gears were meshing correctly because when I had the distributor out this winter the wear pattern on the gears looked really good, I didn't notice any dist. shaft play as I removed it (seemed tighter (2 year old MSD) than the 30 year old dist.), I've always broken my cams in for at least a half hour at rpms above 2-2500 and this was no exception - this one was broken in almost 2 years ago, I haven't taken the timing cover off yet so I don't know if the cam moved, and as for dist. end play, it's really tight being only 2 years old.

This is why I'm stumped - most of these things seem pretty basic to me and should be checked when building/running a motor. And the fact that this occurred a couple of years after it was built confuses me. Cam bearings normally fail early on, dependent on break-in procedures, etc. and I've always kept an eye on oil pressure as I did in my previous motor which lasted 10 years.

I pulled the oil pump apart tonight but didn't find anything unusual. There was some scoring maybe from some of the pieces of the cam/dist. gear, but nothing major. The gears were easily spun and the main one came out of the timing cover smoothly with no noticeable side to side movement. I'll probably pull the intake and the front cover in the next day or so to see what the cam/cam bearings look like.

Bruce, you said Mike went through the same thing. What did he end up putting on the motor? A new timing cover/oil pump?

Thanks for the help.
Paul

 

Were you running a bronze or steel dist. gear ??

Where does that worn metal go ?? all of it down in the pan ??

Paul - reminds me of the time the Csordas's severly bent a few pushrods in Cecil Cty.....no explanation why....slapped some spares in and it ran fine afterwards o No: I dont think John ever figured out why it happened

 

Alan, as you may have guessed, I was running a steel gear and the cam is now junk as well. I've never had an issue with dist. gears before so I didn't think anything of it when I bought and installed the new distributor. Guess I learned my lesson the hard way!

Hey Alan - did you do the deed? You know what I'm talking about! I did! While on the phone with TA getting some replacement parts for this "incident", I bit the bullet and ordered a set of the aluminum stage 1 heads. Now it's your turn - only a few days left...

As I said, I didn't find anything in the oil pump, I drained the oil and it looks pretty good, I'll see what's behind the timing cover next. Maybe the gear has been wearing gradually and finally was worn enough to cause the gears to jump. That would explain not finding any big pieces, which is just the way I like it!

 

I have a that same problem a few weeks ago (do to fact that the oil pump set up to tight)I caught it in time no cam damage my car went slower and slower and had poor idle I check the timing and it was -5 total so it skip one tooth.pull the dis. and the gear was very worn so i pulled he motor out and clean the oil pan but there was not that much metal at all just some very small fine chips. so I would say just put a magnet on the drain plug and change the oil a few times to flush it out. also I'm guessing that the valve spings have been broken and weren't the slowing problem

 

Paul...no Mike just put a new cam in along with a new dist gear.
Too bad the gears aren't replaceable as on the 350! The cam lobes and journals looked perfect.

He was running a mix of 20/50 and 10/30. He may have made a pass withthe oil a bit too cool. He thinks that the motor spins up too fast and the pump just can't keep up....causing drag on the gears. He is switching to the Peterson system....

Good luck////Bruce

 

Paul, I did change the cam, lifters and distributor gear. I also cleaned out some gear teeth from the front of the oil pan and inside the timing cover with a flexible magnet.

I think there could be several factors including running the motor with thick oil that was not heated up enough before the run and the motor spinning up too fast for the pump can keep up. It also could come from "cam walk" since I have not checked the clearence from the cam to the front cover.

My "new" alcohol motor that should be intalled by the BPG Nationals will get a carefull check of the cam to cover clearence and may require a thrust bumper or shim of some sort to keep the teeth aligned.

The first motor this happened to was a few years old (and several hundred runs) before it first appeared as a problem.

Good luck
Mike