81C3Owner

So I'm in the valve train of my new2me '80 L48. I found my spark plugs were oil fouled, so I've been replacing the o-rings.

Second to the last cylinder, I found a completely missing valve stem seal.

In additon to the o-rings, this is what seems to be in use now:


My questions:
1.) why are the umbrellas needed in addition to the o-rings?
2.) just so I'm sure I know what I'm doing, the replacable o-rings are to be mounted in the grove directly below the valve spring keeper.
3.) should I upgrade to positive type seal?



Second problem:
In that same cylinder, the inner valve spring was broken. It is broken pretty low. I actually believe it became weakened and the break only actually occurred as I was removing it. I do NOT believe the valve stem itself is bent.

My questions:
1.) I believe the best thing for me to do is to replace all the valve springs, do you agree?
2.) I don't know what cam is in the engine, so how do I choose the new springs? The engine has a compression test of 180psi +/- 2 on all cylinders... so it could be hopped up a bit but I don't know where.

justinkscott

Ttt -- this is my thread btw; I posted with my wife's account on accident.

Tim81

A lot of builders use umbrella seals along with the standard O-ring seal so I don't believe thats a problem. Others may say something else, using the positive type seals are very good. Yes the O-ring goes in the groove below the valve spring keeper. Make sure the spring is compressed before installing the O-ring.

Tim

oldalaskaman

someone had oil fouling issues prior to you, maybe time to consider a valve job instead of a valve fix. guides maybe loose

justinkscott

Nothing to suggest the previous owner had these problems. All the seals are hard and brittle.



Anyone have any thoughts on the springs? Can I just roll into napa and buy the cheapest springs?

lowes-yellow77

Anyone have any thoughts on the springs? Can I just roll into napa and buy the cheapest springs?[/QUOTE]


if i were you i would take one of the springs to a machine shop they will tell you if they are stock or upgraded with a spring pressure test and also the height open and closed. with this http://www.jegs.com/i/Proform/778/66775/10002/-1

You could always go one step better than stock but remember that springs can kill a cam in a hurry if they are to strong.
If there are shims under the springs that will be a little more work but not too bad just simple math. with this http://www.cranecams.com/product/car...detail&p=25311


lowes-yellow77

oldalaskaman

I think you should buy the cheapest available, try rockauto

azza2u

Upgrading to a positive type seal may involve machining the head to suit. Just went through the same process as you and ended up just putting umbrella seals only in it with new stock valve springs. If you want to see how lightly you got off check out this shot if what used to be in mine.

oldalaskaman

thats a mess, to tne op, I dont remember chevy installing umbrellas

azza2u

And no those aren't orings they are whats left of the old hardened umbrella seals. The rest is missing in action.

I also don't know what cam is in the thing so figured I'd go with the stock springs for now. The ones i pulled seemed stronger but the new one have been ok so far. Test will be if theres valve float when i get it revving past 4k next i guess.

azza2u

Stock was just orings seals. Umbrellas seemed to come about after people started messing with springs and retainers and removing the stock umbrella shaped ones which also acted as a splash shield. Viton pc seals are the evolution of those and also allow for tighter internal clearance when used with actual double springs and not just the normal obesity with the inner dampener.

Reason i chose only umbrella and not to combine with orings was due to reading online about it potentially starving the guide of enough oil to normally lube it. Not saying its right but it seemed logical to me.

azza2u

Damn autoconplete. That should have read "normal ones"

oldalaskaman

good tech. many thanks, bob

justinkscott

This makes the most sense to me. Stock springs won't hurt the cam, upgraded or not and the only thing I have to worry about is valve float... Which should be easier to notice than HP loss from tough springs and/or cam wear.

I mean let's face it... I don't know if bubba upgraded the springs because he needed to or because he wanted to.



Umbrellas:
So do I need both orings & umbrellas? Will it hurt to have both on at the same time? Should I just buy new springs & scrap all the umbrellas?

oldalaskaman

I install o-rings and positive stop 's on all valves, but its a personal choice, if a po installed the umbrellas , might be good to re-install fresh ones,