Ya they will but look at the ramp rate of roller cams they open and close the valve very quickly to little pressure roller looses contact over the nose to great of pressure the lifter will out accelerate the plunger effective changing the cam profile. The name of the game with valvetrain is getting everything to react to the cam lobe instantly.

joe,it,s guys like this newbie that make me not want to post anymore.for the record the seat pressure on my 1200 hp 588,s is 210 lbs with hyd roller cam,s,but what do i know?

What lifters are you using

morel 5045.

Crane did a reliability / performance test about 10yrs ago with their hr lifters...I posted actual article here on OSO somewhere. They went all the way up to like 250 seat / 500 something open and 7k rpm. They incrementally upped rpm and spring psi's to see where they'd run into issues, which they didn't.

edit in: yes, this was a BBC with it's heavy azz valvetrain and 1.7 rocker ratio

Remember the teague hr lifter vs synthetic oil skid article about HP500's ? Well, we all knew it was from too low of spring pressure. Not the oil. He mentioned the same (springs) finally years later.

There is always exceptions. If you look at the original post to the thread it's a production engine. 135 seat would work I didn't have a manual to see they spec'd something diffrent. And would you put stock lifters up to 250 pounds seat pressure. Let's compare apples to apples and oranges to oranges.

The HP500 didn't use a "stock" GM lifter from a 454 dually.

Also, really not a "production engine" considering they were hand assembled at mercury racings facility using Crane and other various vendors parts. (crane, dart, holley, etc)

looks like you have all the answers.so tell us what engine you have in your offshore boat and what the boat is.

It was a durability and performance test toshow everyone not to be afraid of running some more psi than the old myth that became a 'standard' of 135lbs/350lbs with their lifters.

You'll destroy a lifter/valvetrain/engine much easier running a little too low spring psi on a marine BBC than you will running a little too high, if there is such a thing. And yes, I know all about lifter plunger bleed down and etc issues with BBC's...very well.

These Crane HR's used in the blue motors don't have the mildest of lobes.