That could be. The inner springs may not have been the correct length. I was basing my statement on the height of the outer but if the inner was too long, that could happen. I will definitely check the pushrods. Thanks.
Clean and inspect your rocker shafts and rockers. That much initial coil bind would have been hard on them as well.
Just a quick look tells me that one end of the spring was wound closely, presumably to go around the guide. The tops of the springs are wound more loosely. Can't say it was coil bind for sure. I checked 6 pushrods and they are all straight. These inners could have been a little too long. I will pay closer attention as I remove the others. Fortunately, the aluminum rockers and everything else looks ok.
I know the STOCK 350 Buick outer springs have closely wound coils at the bottom and a flat wire dampener inside the outer spring, IIRC the big blocks are the same. It looks from your pictures you have DUAL springs, one inside the other. The flat wire dampener is not considered a spring. Find out what your installed height is, then your cam lift at the valve, and compress the spring in a vice to the open height and see what you have.
Rock, The tight end of the spring goes down for both inner & outer. Spring fatigue from over heating??? Many miles??? Weren't tested beforehand??? Both inner & outer springs have painted yellow strips on original springs. This yellow strip fades to nothing when over heated/run low on oil. Tom T.
There is no yellow on these springs. I dont think the engine has ever overheated since it was rebuilt....possibly before I guess.
I received my new springs from TA and the light bulb came on as I was examining them. The new outer spring is wound CW and the new inner spring is wound CCW. This keeps them from getting tangled up with each other. The old springs were both wound in the same direction, so the could get tangled up and put one into coil bind. I am positive this caused the problem. Also TA does have the correct shims.
Rock, These springs were used on Buicks since the beginning of the "Nail' in '53. They've logged millions/billions of miles without problems. I would attribute the broken springs to fatigue/old age, got too brittle/work hardened from running hotter than normal over a long period of time. Just my thoughts. Tom T.
I don't think they are original springs, Tom. Nevertheless, I have new, qual8ty springs that will be installed correctly now.
After talking to @telriv, he says the original springs are both wound in the same direction. Since the inner spring pilots on the retainer and the guide boss, it makes sense that they couldn't intertwine with each other if installed correctly. So, I guess that puts me back to metallurgy or just old fatigued springs.
Have you confirmed that the cam is not providing more lift then stock? that would surly increase the rate of fatigue. do you have a way to test the spring pressure as you set them up? keep in mind that after the first 4 or 5 4500 rpm blast that they will drop off 8 to 10 psi of seat pressure.
Yes. It's a stock cam. All valve springs are set at spec height + or- .010. Good enough for a cruiser street engine. My valve spring tester won't work with Nailhead rockers.
Running like a top and pulling strong to about 5k, as best as i can tell. No valve float and running smooth! Thanks to Bill Talley and others for the help.
Valve springs still doing ok. Today, I was attempting to modify the vacuum advance when I discovered the diaphragm was dead. New replacement on order. When I get done, this sucker is going to be right.
Wow. What a difference when you get the mechanical advance and the vacuum advance all dialed in! Throttle response and part throttle acceleration were greatly improved and I expect improved gas mileage.
