Broken Exhaust Valve Spring

[rbuckin111]

I recently installed a rebuilt 230 engine in my 64 GMC. The other day it was running perfectly and just quit. When I tried to start it up again, it ran very poorly like it was missing on about 4 cylinders. Upon investigation, I found the exhaust valve spring in the number 2 cylinder broken. Anyone have a thought on how one would break a valve spring? Should I be looking further for the cause of this spring breaking? As serious as this is, I would have thought this would have only affected one cylinder and that the engine should have run pretty well with only one miss. Have I only discovered the tip of the ice berg? Thanks for taking a minute to give me your input and ideas.

[1963c-10]

Im no expert on this subject, but heres my two cents worth. Could be misalignment between valve guide and seat or even a defected valve. I read an article in chevy high performance a while back that said as many as 1 in 5 valves have defects. Could also be an oiling problem on that valve spring or just a defected valve spring. Were the springs new on rebuild or reused? Also...stock cam or high performance cam? Normally a high performance came will put more pressure on springs due to the higher lift on the lobes. I would recheck timinig also just to make sure that timing hasn't moved. I would tend to agree with you that the problem should be in one cylinder only, but might not be a bad idea to drop the pan for a bottom end check. The 230's run off gears and not a chain, so I wouldn't think that its in the front of the engine, but this is all my two cents worth. I dont think that Id try and turn her over again w/o a good look at the bottom and top end and checking timing set at TDC.

The only other thing I would check is the fuel system to make sure that you dont have a fuel issue that caused it to run rough also. Dirt or rust in the tank if it sat during the engine swap, filters..etc.

[rbuckin111]

Just thought I would give an update. Replaced the one exhaust valve spring and everything is back to normal, running smooth and great. I am amazed at the amount of difference one little spring can make, going from almost not running to running well. Hopefully this will be the last one of these I have a problem with. Still have no idea how a properly adjusted valve spring could just break like that. Thanks for your input 1963c-10!

[1963c-10]

Have no idea either. Best guess is it was just a defective spring. Glad you got it running though. The 230 is a great engine. I still have the original factory built 230 in my 63 and it still runs strong, doesn't blow any smoke and does ever job that Ive required of it.

[Alan's Classic]

Moved to engine and drivetrain

[clinebarger]

Most rebuilds dont get new valve springs, Worn USED one's are often shimmed to desired seat pressure

[crazy longhorn]

Originally Posted by clinebarger

Most rebuilds dont get new valve springs, Worn USED one's are often shimmed to desired seat pressure

2nd that, & will add....an old set of valve springs, can "spoil" the sweetest overhaul crazyl