[Jon]

On the way home this weekend I broke a valve spring. No racing, took it to 5000 RPM's maybe once or twice. It has happened before and I have several spares but am thinking about replacing them all.

Could there be a coil bid problem or do they just get old. These are 20 year old Sig Erson or Isky (can't remember which) but a second set from the originals for sure.

The more research I do to find a set, the more questions come to mind. Dual spring, seat pressure, coil bind height, spring rate. The cam is a MP 284/.484 lift so extreme spring rates are not necessary or desired given the old aluminum retainers. (I may replace those also, it's no fun ending a nice day on a sore note).

Anyone have information on this subject. Oh, small block 340, with factory iron heads.

Thanks

[dave-r]

I have an old hydraulic lifter I made solid so I could check for things like coil bind on the engine.

But you can also check the installed height and then duplicate that off the engine in a vice and compress further to equal the valve lift.

I have seen rockers break for one reason or another but have never personally come across a spring breaking. Although I have heard of it happening before.

Make sure your valve spring has only the required amount of seat and open pressures.
Any less and the valve will float. Any more and you are putting undue pressure on the valve-train and head.

Look at quality as well. You can normally use price as a guide to how good they are.

[Jon]

Why didnt I think of that?

Here's a pic of the same spring (a spare) with installed height minus .484- ish compression. Also the broken one in place. The inner spring is just a damper, not to be considered a dual valve spring correct?

Thanks again Dave.

[dave-r]

Yes the inner is just a damper. But you have to check that as well because if it breaks it can get between the coils of the valve spring.

Usually if the valve spring is rated right for the cam you don't need the damper.