I am going through a good running 455 that I tore down to fix a few things - cam change (back to stock), oil pan replacement (changing from deep Moroso pan back to stock), and replacing torque converter (changing from high stall back to stock).

Previous owner has double valve springs and white Teflon positive valve seals on machined .495 guides. I think I'll ditch the double springs, don't think a big motor that never sees 4000 rpm needs them? And going back to umbrella seals - good idea? I've heard the positive seals don't let enough oil to the stems, opinions?

 

PC style seals work just fine.
And you really need to check spring pressure before you change them out. I’ve seen double springs have LESS pressure than some singles.

 

My engine has what look like “double springs” but are really factory rate single springs with a damper.

 

Further checking - my spring pockets are 1.500 and the installed height is 1.880". Are those numbers the same as big block Chevy? I'm having trouble finding single BBO valve springs online

 

I can supply springs, but are you sure about that installed height?

 

Yes, exactly 1.880". PO had a single .010 shim under each but measuring without the shim I get 1.880 - why do you ask - is this an unusual number? I could have non std valve lengths or sunken seats

 

Could be the retainers also. A lot of aftermarket retainers give you more installed hgt than factory. Nd like Mark said before you waste money on springs I would take yours to someone who can check the seat and open pressures. They might be just fine the way they are.

 

Further checking - I have some specs on the double springs and a set of BBC springs I have

Double spring on the heads now
120 lbs seat pressure @ 1.880" installed ht
280 lbs open pressure @ 1.380"

Single BBC spring
80 lbs seat pressure @ 1.880" installed ht
250 lbs open pressure @ 1.380"

Which set would you run?

 

if you’re going back to a stock cam/lift you won’t have either of those open pressures. what’s the cam specs and lift?

are the valve guides replacement bronze or stock iron?

 

Cam is Mondello 20-22 with .496"/.520"
guides are stock and have been cut down for pc seals

 

Then you’ll see in or about those spring pressures. But you need to know where bind is as well. If they’re ok on bind then I’d use the 120/280 spring package.

 

that’s what you meant you you said you’re going back to stock?

then go with the higher poundage springs

 

Oops I grabbed the wrong cam specs - will have to research a bit

 

Either way, 80# on the seat is to little.