Whiteknuckle

Hi Bob,
I think the hydraulic roller reference forumla31 and I made was to the crane cam that is in question. You are correct in the 330HP cam is a flat tappet. Give me a call some time.

98itrwhite

the reason for roller cam was to upgrade from what i have and the merlins were bought used and are setup for a roller. so there complete other than rockers. i called crane today and rec. this cam part#139011. also what would it take to convert the merlins to a flat tappet cam?

Pat McPherson

I believe that the valve springs are about the only thing that would be different. Being that you bought used heads, you may want to install new springs that match the new cam you pick anyway.
I agree with the others, if you are limiting the engine to 5000rpm, a roller cam may be a wast of money. I would suggest the Crane/Merc 420 hydraulic flat tappet cam. Lots of guys have had good success upgrading 330s with that cam...

98itrwhite

if there is not much gain for me with the roller i am all ears for the flat tappet cam. does any one have a part number for the merc/420 that was mentioned. i would still have to get valve srings and retainers push rods and lfters if not included with cam. can i use my stock rockers? what kind of valve springs would work with this cam?

Whiteknuckle

98,
Get with RMBuilder and work with him on a cam and accessories. He is the best. Let him put you a package together for what you have.

Pat McPherson

If you know the spring rate and seat pressure of your current springs then you can compare to what is recommended for the new cam.
The push rods in a 330 are kind of wimpy, I would buy the next size up; the guide plates on your new heads are likely for the larger dia push rods anyway.
You will need long slot rockers or you may want to go with roller rockers as that is what was used in the Merc 420.
I don't know the Crane # but you can find in pretty easy on Crane's web page. Or someone may chime in with the part number for you.
Yes, buy new hydraulic lifters, they're only about $60.
If Crane sells a kit for new cam, lifters, springs, retainers, and locks, that may be the best way to go...

formula31

Having had more than my share of issues with pushrods I would suggest going to the one piece 3/8' hardened comp cams pushrods. Personally I like the flat tappet cams Im am running in mine. they are 224, 232, .527 .553 at 114 sep. timed at 110. Could go bigger but I have very close cutouts and need to be very watchful of reversion.

98itrwhite

i have decided to go with the merc 420 cam (crane part#132561) i am useing dana marine flo-torque manifolds with tube style risers do you think i will have reversion probloms?

amer3

500hp cam is # 11-000-5 grind # cb 5447/5209 h 114.0
send my cam from my 500hp to comp cams and that is what it is.

in.576 ex.579
[email protected] in 240 ex 246
lobe sep 114.

Pat McPherson

No, I believe that cam was also used in the 370HP and 400HP with stock cast iron exhaust.
To be safe, set your idle at 700+rpm.