Mercruiser 420hp roller cam upgrade
 

I'm going through my mercruisers 454 420hp and I'm wanting to upgrade to roller cams. Has anyone had any luck finding a good roller cam setup that works good for them? If not I could use some help from someone who has more knowledge in roller cams than I do, to find a good match.

I would love to get as much hp that I can while still running pump gas, would also like to squeeze more rpm out of them. Right now they are still running carburetors, but will probably be putting on some holley snipers efi "the ones rated to 500hp" unless I find a better setup.


I believe the stock cams are

420 Flat Tappet Hydraulic 298*/306/ @ .005"228*/236* @ .050".312"/.324" Lobe Lift.530"/.551" Lift Valve114* +5*

What else are you going to do to them??
731 or similar will prob be the best all around. Very close to the 500efi cam specs as well.
741 or similar will prob make a little more power in the 5000-5500rpm.

Crane 731 copy Teague Custom Marine | BBC Mark IV Billet Camshaft - Stage 1
Crane 741 copy Teague Custom Marine | BBC Mark IV Billet Camshaft - Stage 2

I just did a lot of research and found quite a few options. As Griff just posted I went with Teagues 741 copy and had them match all the components. They use things that typically work well and work well together.

You are running a cam like the 741? How do you like them? Is there still ok low end take of power, and what's your red line? The engines are out of a chris craft stinger 390x

just changing cams is not going to yield much improvement in hp........heads and cams together will and the efi will help

I am aware, I just don't want to lose hp just because i decided to change over to a roller setup. Im not to familiar with a roller cam setup so was looking for help from someone who works with them more.

[QUOTE=Griff;4923883]What else are you going to do to them??
731 or similar will prob be the best all around. Very close to the 500efi cam specs as well.
741 or similar will prob make a little more power in the 5000-5500rpm.

I'm not doing to much to them besides a freshing. I already have aftermarket exhaust, and was planning on converting over to roller and matching them with some new valve springs, then efi and ignition later on.
the boats a project and I'm not dumping a lot into it until I get them engines running good and getting all the bugs worked out of the rest of the boat.

Things will add up pretty quick, cams, lifters, push rods, valve springs, rockers........possibly retainers and clips depending on what heads you have......good luck

I don’t really know how I like it as it hasn’t been run. I’m going to start it on the stand tomorrow.

The 741 is a little too much in a 454 without head work and increases in compression.

A copy of the 621 500 EFI cam is what I’d go with (or something close to it). It’ll keep the power band about where you’ll need it for that Chris Craft. I think the duration on the cam is almost identical to the 420 cam, too.

Whatever you go with, get it on a Gen VI core (Crane 621 is a Gen VI cam). You’ll be able to use a Gen VI timing set with the retainer that it uses to keep the cam from walking versus having to run a cam button and all that.

Definitely run as far away as you can from flat tappets. They’re engine killers at this point.