mr303

While replacing my valve stem seals a month ago I found that one of the damper springs was broken. This is a stock L48 with 115,000 miles on it, runs perfectly.
Should I replace all the valve springs and dampers with a stock rated set?
What are the stock pressures, seated and opening?
Would replacing the springs cause any added wear to the cam and lifters?
I was intending to do this with the heads in place.

REELAV8R

I guess if it were mine I would probably just replace what is broken. That being said I would also take one more step and take a few springs off and get them tested to see if they still met the open and closed specs for the engine and to check the condition of some of the other dampners.

According to my manual for the 77 L-48 the spring pressure is;
75-84 lbs @ 1.70" intake and 1.61" exhaust.
194-206 lbs open which is @ 1.25" intake and 1.16" exhaust.

Hard part is taking the springs off. I can say using this style valve spring compressor is a real hassle, but I see you've already done this if you just replaced the valve sem seals;
http://www.summitracing.com/parts/otc-4573/overview/

After my last valve spring job I got this style instead and it is much better.
http://www.summitracing.com/parts/mor-62371/overview/
Although that price is a bit much. Shop around and you can do better.

Tom454

Also.... if do decide to replace the springs, if you can, test them. I have been getting new springs that are off spec. and un-useable from well known vendors and manufacturers.

mr303

Thanks for the replies, I think the original springs will be pretty tired, my thoughts were that while replacing the broken damper I might just as well replace all the springs and dampers. I have been looking at the Edelbrock 5802 springs, 80lbs seated 200lbs open.
My main concern was placing a bit more pressure on the cam and lifters might create problems.

jb78L-82

I had a OEM valve spring break in the 80's on my L-82…Replaced that one spring and drove that valve train until Spring 2014 when I completely rebuild the motor with roller cam and AFR heads…FWIW

Tom454

I have this tester:
http://www.cylinderheadsupply.com/kl1469.html

I used this calibration spring to calibrate the tester:
http://www.compperformancegroupstore...Category_Code=

I purchased these:
http://www.compperformancegroupstore...Category_Code=

They were off more than the allowable variance.
I called them up, had them grab a set off the shelf, had them measure them and those were also out of spec.

Other brands & manufacturers had the same issue.
No quality control anymore.

AirBusPilot

Always replace every spring.

REELAV8R

I found that you can get your springs tested at some machine shops and most engine shops.
The springs you are looking at sound good if those specs are accurate. For $30 I guess I'd replace them all too.
You can get a couple checked to see if they meet the advertised spec. I don't think 10lbs one way or the other is going to matter much on a stock L-48.
Too little pressure valve control could become an issue.

Solid LT1

Find an auto machine shop in your area.....they should be able to set you up with a set of USA made Melling valve springs for under $60 for the set.

63mako

Those specs are exact stock replacement pressures.
Always replace all the springs. The stockers are 40 years old. have 115,000 miles on them and fatigued if one broke.

PAmotorman

this type fits over the rocker stud and is easy to use, just use a nut to wind it down and compress the spring. I bought this in 1955 and I don't know if they are still avaiable

mr303

Once again thanks for all the advice, it seems that replacing them all is the best thing to do.
I have been using a pretty cheap little compressor to do the stem seals but will upgrade this to one of the tools suggested and make my life a little easier.