Engine/Transmission (1994 - 1998) HELP exhaust valve spring info needed (engine guys)

[JMauro]

maybe i'm being over cautious but after installing a pacbrake (with hole plugged) i ordered springs from PDR. now i build race engines and this truck is used to tow my dragster trailer so i'm no stranger to engine mods. i pulled one of the springs and checked it on my Intercomp digital spring tester (checked calibration before using) and it read 88#'s @ 1. 928" which is the rough installed height i measured. the new spring checked 151#'s @ 1. 928". imho that's one heck of an increase in seat pressure... probably more than necessary. heck that's as much seat pressure as we run on some good sized solid cams that spin up to 7500 RPM. my concern is that much pressure is gonna be hard on the exhaust valve train. the open pressure wasn't a lot more considering the seat pressure but i don't know the valve lift so i couldn't get an accurate feel for the open pressure. i thought i had read a post (or more) about possible valve train issues.



any help would be appreciated.

 

[Bob4x4]

I have had my springs on for over 100k... ... ..... no issues,no worrys



Bob

 

[Joseph Donnelly]

Cummins wouldn't use them if they gave problems. Your mushroom tappets are well over 1" diameter on the feet, and open pressure is what really hurts--as you noted, it isn't too much with these springs. More seat pressure keeps the valves from blowing open, or in racers, from bouncing off the seats. "Everyone" runs at least 120 lb on the seats anymore, at least for the last 30 years--even with wimpy chevy lifters of . 842" diameter.

 

[JMauro]

thanks guys, guess i just needed a little peace of mind. it just seemed like a big jump in seat pressure even though the open wasn't nearly as stiff. i had considered all the points mentioned (everyone uses them, lifter face diameter ect. ) just didn't really think it would require that much more pressure. having said that better stiff springs than pieces of valve wandering around in one (or more) of the holes.