After a 20 minute drive the other day, we stopped for 15 minutes or so and then pulling out onto the road, I noticed a loud ticking noise that followed the speed of the motor. Higher r's, faster tick. It idled a little rough so I babied it home about 2 miles, staying below 1500 rpm's. After pulling the valve cover, I found a broken exhaust spring on cyl 2.

I pulled the rockers on both exhaust and intake- valves are sitting high and don't look bent and the push rod is still straight. It's looking like I got lucky and only have a broken spring, no other damage. I was planning to pull the exhaust and intake spring, have my speed shop measure the spring and then get a comparable replacement. The motor has <5k miles on it and I don't drive it hard at all, no drag racing, etc. It's really a weekend toy that gets driven once per month or so. Based on the low mileage and minimal usage, I was planning to replace only the 1 spring. What are the risks in this vs. swapping all 16 springs? Also, is there anything critical in the cam specs I need to swap the springs and remove/replace rockers? I had one shop suggest tearing the motor down, pulling the cam and getting a serial number to find specs about it. For simply swapping springs, I couldn't see going through this trouble. What do you guys think?

I'm running a 383 stroker with an auto tranny. Unfortunately, I don't have any specs on the motor or cam- it was built by a guy 3 owners back from me. I talked to the prior owner and the one before him and neither have any specs or contact info for the builder.

Here's a close up of the damage:

 

Just hope it didn't drop that valve in the cylinder, then your getting into a whole other ball game... Looks like it has 918 springs in it..

 

Hmm... it looks like the 918's have a round wire inner spring, mine have a flat inner spring. looks more like the inner spring is metal ribbon than wire. Does that give any clues? I dropped my broken exhaust spring and good intake spring at a local speed/machine shop yesterday and waiting to see what the come back with.

Thanks

 

Those are not 918's as they are not beehives, those are dual springs. Maybe 921's or whatever comp duals are. They dont appear to be patriots, i would guess comp or PAC.

I would say being a dual is the only reason you didnt drop a valve.

 

Here's what mine look like, with the flat inner spring. I haven't seen much of this style in my searches:

 

Yes I just noticed that.. Couldn't see it from my phone..

 

Is it just me or is that inner spring busted up too?

 

I broke an exhaust spring on a 306 a few years back the same way. Drove about 25 miles stopped to get gas, and when I started it back to leave the engine was missing terribly. The springs had 10k miles on them.

Replaced the one spring and never had another problem.

 

Typical old school small block chevy stuff here, it's just a single spring with a dampner.
Measure your total valve lift off of the top of one of the good retainers, (I doubt it'll be much more than about .500" lift), and get a complete new set of springs, retainers, locks, and seals good for a little more... say .550". It's always better and cheaper to do it right the first time than do it over the second, and maybe cost you an engine in the meantime.
I would doubt that the rockers would would be hurt, but I'd look'em over real close. You could also have a machine shop check the pressure on your old springs to help you get more in the ballpark, but unless you've got a billy-bad-azz radical cam it doesn't take much of a spring to spin a sbc to 6K or better.
Hope this helps.

 

the engine in that pic is definitely an old school sbc...