98itrwhite

the merc 420 cam is what i am going to use this year on my 330hp. along with merlin ovals and a 800 holly (not by choice but it will work) stay with the 750 though if you already have it ,much more friendly on these small hp motors. good luck summer is coming

PatriYacht

The 420 cam and kit and a set of roller rockers is the next logical step to take. It will make a noticable difference. The carb won't.

mtocrs1

Do you know the part #for the 420 cam kit. Does the 420 stand for 420HP?

98itrwhite

it means it came in the merc 420hp 454. i wish by droping it in it would give 420 horsepower........lol, but i heard it works well in the 330hp 454. if your looking for the flat tappet cam i have the part# at work and i will post it up tommorow if no one posts before me.

Pat McPherson

Go to the Crane Cams web page and look under BBC marine camshafts and you'll find it easily.
Yes, 420 means 420HP; for a 420HP 454. The cam was also use in the Merc 525SC.
I've got a stock set of GM L-29 large oval vortec heads that will out flow those peanut port heads and raise the compression with flat tops from 8:1 to 9:1.
$300 plus shipping...

Payton

The Crane 241 is the flat tappet cam that is very close to the one in the 420.

98itrwhite

the part # for the crane/merc 420 cam is crane part#132561. thats for the flat tappet version not roller.

Payton

You are right.
http://www.cranecams.com/?show=brows...61&lvl=2&prt=5

KAAMA

iTrader: (1)

A good aftermarket exhaust system will be a big improvement over the Merc cast iron stock exhaust. Once you have done that, the better your engine will respond with any mods.

Also, a good set of roller rocker arms would really be an added benifit over the stock stamped steel rocker arms. Good advice is given by Patriyacht and Pat Mc---I agree with there suggestions. Have fun.

NightHawk

http://www.powerboatmagazine.com/tea...2006/01_06.php

Some info in the second response.