Exhaust exhaust manifold leak

LILCBRA said:

1) Yes, it is possible to swap valve springs while the head is still on the engine. You will need adapters to connect compressed air to the spark plug hole of the cylinder you're working on. That allows the valve to stay in place when you remove/replace the spring.

Click to expand...

I saw this done once with a piece of paracord fed into the spark plug hole and the engine turned by hand to hold valve with wad of rope.
It made me nervous but he pulled the tail he left hanging out after turning engine back a few degrees and all was good.

Enzio said:

Found a broken piece of a rocker on the passenger side when I took the rocker cover off. I

Click to expand...

WTF!?!

A broken piece from a rocker arm??? That doesn't sound too good....

Them small blocks are tough as hell
Once My buddy says his engine 'went away and was missing a little'

3 weeks of daily driving later and we figured out a ex. valve had broken off and speared a piston but it still ran.

I'll readily admit that I don't have all of the answers, but here's my take with what I think mixed with a little knowledge.

I'm pretty sure springs aren't made to an exact pressure, but a range of pressures that are acceptable. Let's say +/- 10%. In testing Windsor components and operation, engineers most likely discovered that in order for the valves not to float they had to use a specifically rated spring - not so strong that it wiped the cam lobes, but strong enough to close the valves under prescribed conditions. The length of that spring had to be strong enough to close the valve while having enough clearance between the coils to be able to fully open. So, in terms of keeping parts uniform, they come up with what they found to be an acceptable length of a specific spring and had to give manufacturing tolerances to ensure that when mass produced and factory installed, every spring met the requirements of every engine every time. So that comes down to where you are now, installing factory acceptable parts using factory prescribed methods and specifications. Chances are they would work fine without shims, but you would likely have valve float and possible valvetrain and or piston damage at higher RPM. And, as I'm sure you already know, spring pressures are variable depending on how much they are compressed. If a spring had little to no preload, the valve may or may not fully close either, which is no bueno!

Upon searching for more info to share I come across this article from Comp Cams. I hit the pressure tolerance on the head!
It also says that your installed lengths are good to go if they are all within +/-.020, so your springs are good as a set. The free length isn't as important as the installed length as long as there is no coil bind and the pressure isn't too great. I'd say that the lengths of your new springs are probably good. About the best way to check is to measure between the coils as best you can when the spring is installed and make sure that your overall cam lift is smaller than that number. So let's say your cam has .500 valve lift, you should have AT MINIMUM .500 or more between the coils when the spring is installed.

And the .500 between the coils that I'm talking about means added up between all of the coils, so if you had 5 coil spaces, they should all be at least .100 apart. Just wanted to be sure that I was clear about that....

Yes, .500 when the valve is closed.

One thing that I'm curious about is your new springs. I looked them up a few minutes ago and Summit says that their free height is 1.97. You say they are all actually 2.05. I think that it would be critical to double check for coil bind when you install them. These might have been engineered to be installed without the shim? It's hard telling..... But from the info you've given vs what's advertised, your new springs may not be correct....