mcollinstn

It's not a matter of HP per cubic inch. It's a matter of HP.

You got 60% more horsepower. You got valves that are 50% heavier and have 25% more lift. You gotta have springs strong enough to control the valve, but it's gotta move 25% further with each lift event.

You also got a marine motor where 200 hours will be comprised of 10 hours idling, 100 hours at 3000rpm, 70 hours at 4,200 rpm, and 20 hours at 5,000 rpm. This is far different than a street car application, even one that sees weekend grudge match duty.

A marine engine at 500 hours equates to a street car at 100,000 miles (I can't remember where I read this - and feel free to quote a better comparison). This means (assuming the above comparison is valid) that a 200 hour performance marine cycle is equivalent to a 40,000 mile auto cycle.

Granted, 40,000 miles is not a severe lifespan for a car valvespring (On the flipside, I went thru several GM 2.8 V-6 motors in less than 30,000 miles each: #1@22k, #2@38k, #3@65k, then I sold it).

I, too, am VERY interested in the HP3 valvespring lifespan.

Scott

mcollinstn,

Thanks for the support. I am in a seminar this week in Philadelphia I had to give a presentation yesterday and I'm not even sure what I said (hard to stay focused)
As much as I want to answer your question I can't but can assume they were set at specified heights. The original springs that were way out of whack (no longer offered) were set up by Merc , GM or who ever it was that year! Merc says they build them but I have to wonder just how much they do or if they are built to spec by someone else.
I had decided to have my heads cleaned up and had some exhaust relief done on them so I did not install the new springs. The head guy that I used seems to have a great reputation and I had to put some trust into his work. I would hope they are at spec. I will be checking them this spring and if I find anything strange I'll post it.

later

With all of the spring talk, are you able to replace the springs with the heads still on the motor. or do the heads need to come off for spring pockets to be machined etc when changing to the new springs? ive changed broken springs on cars many times without pulling heads but always installed factory replacement , just filled the cylinders with air and switched the springs, what about retainers? or you swapping retainers also?
later

mcollinstn

Later,

Yeah, unless you got head or valve issues, just air em up and drop new ones on. Can't cut pockets on the motor, since the pocket cutter has a pilot that goes in the valve guide.

shawn

I called Merc last fall and asked about when to do springs and the idiot said to run it until it broke, the worst that would happen is I'd break a cam. Not very impressed with their techs.

Shawn

later

ok so am i getting this correct the comp cam spring is the way to go, correct? is the part number 929 or is there more, two the number, and will my present retainers work i have 98 carb motors.
thanks
Later

mcollinstn

P/N: 929-16

GETTINBYE

Later,

From what I have been told the retainers need to be changed also. They were part of the problem. Have heard Merc. used a GM retainer with the Crane 99895 spring which over stressed the inner spring.

The correct path for the fix is, as stated in other posts, the Comp Cams 929-16 spring @ 1.88" installed hgt. and the Crane 99955 retainer. Valve locks are the same. You could also use the new Crane 99896 spring @ 1.906" installed hgt. however it seems people are prefering the Comp spring.

Mark

bobby daniels

HEY JEFF THEN CHANGE YOUR SPRINGS THIS YEAR !!! LEAK DOWN WILL NOT TELL YOU ANYTHING EXCEPT THEIR WORKING NOW WELL ENOUGH TO HOLD THE VALVE CLOSED ,IT CAN'T TELL YOU'VE RUN THE CHIT OUT OF IT AND ITS BEEN CYCLED TO DEATH
MARK THE 929 COMP IS TOUGH AND A VERY GOOD SPRING I'VE USED FOR YEARS ,IF THEY OFFER A COATED VERSION USE IT IT WILL PAY FOR ITSELF ,

AND ALWAYS USE NEW LOCKS AND RETAINERS IF YOU DON'T IT IS LIKE CHANGING OIL AND NOT THE FILTER ,,,CHEAP ,AND JUST PLAIN WRONG

SCOTT YOUR RIGHT ON TARGET

bobby daniels

JEFF NOT YELLING ,BUD ITS THE WAY I TYPE ,,,, JUST TRYING TO HELP YOU ! ITS CYCLES NOT JUST HRS. ,,YOU SAID YOU RAN ALONG WAY WOT THAT BUILDS HEAT AND KILLS TENISON OF SPRINGS ,
CHECK SPRINGS WITH SPRING TESTER ,,EVEN A MOROSO HAND HELD ONE ,,,WITH THAT ONE JUST CHECK THE DIFFERENCE FROM SPRING TO SPRING TO SPRING IF THERES ALOT CHANGE THEM -----929SPRINGS ,RET.,LOCK, LESS THAN 150..00 NEW MOTOR ??OH MAN !
BUT ITS YOUR MOTOR ENJOY