How do I fix a broken valve spring SBC ?

That style of valve spring compressor is pretty inexpensive at most parts houses and many have the "loaner" program if you don't want to keep it. Rope is damned cheap at any hardware store.

Good Going TommyD glad to see that you got it going and got home ok.

 

That works sometimes but the rope keeps the valves right up on the seat and you don't have to fiddlefuck with them because they aren't going to slip down against the piston.

 

I just did a set of valve seals on a SBF with that tool. Put it on compression stroke stuff a couple of feet of soft rope in then bring it up by hand till it stops. Change spring or seal then back off by hand and on to the next valve. Those fancy tools are nice but sometimes you just don't have the room to use them but you can get that bar in there (like my 64 V8 Ranchero).

 

is the broke spring ... from the EX or IN?

 

It is an exhaust spring that is broken.

I thought I could pull the good springs from another cylinder and compare the heights to see if they are the same.

 

<P>I have seen this done. Knock the center out of a sparkplug and tap it with a pipe tap.&nbsp; Then rotate motor till both valves are closed. Install airline fitting into sparkplug piece and then put plug in motor on that cylinder. Apply compressed air via airline connected to fitting in the plug. Then use the tool pictured above to remove the keeper and spring. Reinstall new spring and keepers and then remove airline and reinstall good sparkplug.</P>

 

I do the same thing with my MAC compression tester. It's got 2 separate hoses, 1 on the guage and 1 on the fitting that screws into the plug hole with a Q/D to connect them. Just happens that the Q/D connector is IM style same as the air hoses I use in my shop. Screw the hose into the sparkplug hole & plug in my air hose. Done. Good way to check for bent or leaking valves as well.

 

from the first post in the thread....

 

if you use air make sure the car is not in gear if it's a standard, left in gear the piston can be pushed down by the air rolling the car onto your foot, i had a friend tell me his drama when it happened to him.

 

Technical question: (am I figuring this correctly?)...

The spring install height is 1.700. The exhaust valve lift is .454 and the spring coil bind height is 1.153...added together they are 1.607...Is .993 clearance enough room to avoid coil bind issues?

 

1.700
-1.153
---------------
.547 lift is where it binds
- .454 lift
-----------------
.093 clearance is fine

.050 min on street is rule


Posted using the Full Custom H.A.M.B. App!

 

I bought the new springs. The ones on the heads are dual, the new ones are single. Is that an issue on the street?

 

fitment of the retainer as well as the spring to the spring seat is important.....open and closed(seat) preasure is very important.......wether its dual or single not really.....spring preasure is spring preasure.

A dual spring will run hotter(friction) than a single......

Im not going to read 3 pages of how to change a spring...so....what is the cam ? hyd..solid...hyd roller......Im assuming hyd with that lift

 

Are they really dual springs, or single springs with a flat damper?

 

Should I swap the damper from the old springs into the new spring?

The old springs currently on the heads have a flat damper "inner" spring. I do not know what these old springs are matched too, I assume they are stock GM springs.

The new springs that I purchased are a close match to the specs provided for my cam. They are a single spring without an inner damper.

Will running without the inner damper be less safe? (On the old springs, the damper spring kept the valve from dropping and getting bent when the outer spring broke)

Seat - Cam Matched Spring (114 # 1.7") New purchased spring (105 @ 1.7")
Open - Cam Matched Spring (303 @ 1.270) New purchased Spring (296 @ 1.200)
Bind - Cam Matched Spring (1.153") New purchased Spring (1.153")

 

But they carry spare valve springs?

 

I could be wrong, but, the spring breaks line up with the ends of the inner spring. Inner spring sharp edge could be rubbing a nick on the outer and creating a 'stress raiser causing failure. Linish sharp edges before assembly?

 

You sound like a Stress Engineer to me. We call stress raiser Kt's

 

I made a "Fork tool" to press down the broken spring so I could get the keepers off,
it mounted on the rocker arm bolt and when tightened down pushed the retainer,

Then I had an air tank to pressurize the cylinder.....

It took 10 minutes on the side of the road , and I was lucky the valve head was not damaged ,

 

Kts?.?
No mate im a retired stressed Engineer..LOL.