liquidlounge

iTrader: (1)

Appx. 140# seat pressure / appx. 370 spring rate. The better Morels require 150# minimum on the seat IIRC. I'm wanting to keep a 509 build at no more than 500hp for several reasons; 1- I don't want ANY drive concerns and I know the drive will be hammered on. 2- I want to retain the silent choice. 3- Safety (a few family members will be allowed to use it), its a pretty speedy hull already; a somewhat light 24' vented cat hull. I was thinking of getting a single pattern cam cut with a symmetrical, somewhat low intensity lobe. Backing off on the duration for silent choice, I'm just afraid that the torque will just hit too fast and hard for the drive with a more modern, higher lift lobe that's on the short side duration wise.(I already have upgraded heads with higher compression and sub 300cc intakes) So are the GM lifters the best thing going for a mild cam?

Black Baja

iTrader: (2)

There is a new lifter out that sounds very promising. Bob M. @ Marine Kinetics has all the specs on the new lifter. From what I'm told it stands up against other lifters very well.

liquidlounge

iTrader: (1)

And this will work good with lower spring pressures? Thanks for the reply. I probably can't reply back until Monday.

Griff

GM lifters are only good to so much lift. Not sure of the exact max lift, but I think its in the .550 range.

SB

iTrader: (1)

Lower spring psi's typically don't matter. It's a matter of how high of spring psi's (+lobe intensity/jerk/acceleration/and other lobe things I don't have a total handle on) the lifter can deal with.

MILD THUNDER

iTrader: (3)

The morels seemed to have a good reputation for a while . the machine shop I use has used Johnson lifters for some time now with good results as well.

What about the Johnsons did they do that left the morels "in the dust"? When did Johnson develop this new lifter ?

I've been running morels for a few years now because I was told they were the best here on oso. I did have one collapse on me, but was told it was more than likely a fluke.

I don't know about the Johnsons, but morels 5045 called for higher spring pressures than the 4603's. I am on the light side of spring pressure with a 4603 lifter, well, actually what john Callie's recommends for them , with 165/450ish . pulled to 6300 on the dyno, and been run around 5700-5900 in the boat , never any signs of valve float .

liquidlounge

iTrader: (1)

I'll have to check the part# then on the Morels I have. I know they have the .750 wheel and iirc they had a 150# minimum seat pressure spec. I really want to run silent choice, which is going to require me to shorten up the duration. Short duration, high lift and high compression = high cylinder pressure, correct? Even if detonation isn't an issue, and I don't think it will be, I think this set up will be a drive shredder. The cam that I have now is a 229/229 -.600 lift, 114 lsa . I have 17.5" of dry pipe to the wet elbow and diverter to the y pipe. I'm pretty sure this set up will be in the 550+ range with my heads. I've decided I would be happier in the sub 500hp range for what I want to do, which can be done with a pretty mild cam with my heads...this means I don't need a lobe that requires 150#+ seat pressure, which means I don't have an ideal lifter in the Morels I have. So, is the GM roller the best option for me? I re-read my post #1 and I must have been off my game that day.

abones

the GM roller lifter with the dog bone retainer set up will be just fine for your application, it can and will handle 600 lift. and will run your pressures with no problem. In my humble opinion.

MILD THUNDER

iTrader: (3)

Something else to ponder. Changing wheel diameter on the lifter, can also affect the valve timing events. Minimal, but .............

rmbuilder

LL
The force, or spring rate, that’s required for your valve train is a byproduct a very simple equation.
F= M*A

At sub 5200 RPM, on a lobe with a modest acceleration derivative that element is in check.
The mass of the BBC valves on both sides are some of the highest values found in engine design, particularly if you utilize an Inconel exhaust valve. The rate of your spring should ideally be ~ 420-440 to prevent premature spring fatigue and seat erosion at those mass levels.

If, for example, you utilize an Isky 8005 Plus, with a rate of 433#/in, set at
1.850” your seat force will come in at 151 LBS, with an open force of 411 Lbs. at .600” lift at the valve. That would allow you to utilize the assets your current Morels bring to the table while making for a very stable package.

Bob