PDA

View Full Version : camshaft question



smokediver
07-23-2006, 09:12 AM
I am in the process of pulling the motor out of my boat:mad: I have a newer 5.7 merc motor with vortec heads . i am having the heads cleaned up and replacing a couple of bent valves . a little machine work needs to be done for new springs . I was wondering what a good camshaft upgrade would be , making power in the 5000-5200 rpm range . it is a roller cam now and i think i will stick to that .... unless there is a better flat tappet option .... i would like to also keep my tbolt v ignition ....

Cuda
07-23-2006, 10:26 AM
Just the other day I found the build sheets to the engine that currently sits in the Minx. It has Vortec heads, and ran great in my Formula 20 Sc.

Cuda
07-23-2006, 10:28 AM
Did you ever find how the water got in there?

slacker
07-23-2006, 10:53 AM
gm uses a vortec headed motor(part#ends in 602) in their circle track crate motor program....the springs are definately the weak link, they recommend replacing every 10 or so races which doesn't translate into too many hours of hard use.....
do yourself a favor & have the guides & spring pockets machined to accept larger dia springs....you will be much happier in the long run.......
car craft mag recently did a budget blower build w/vortec heads that sounded like it would be perfect for a marine application.....a outfit in texas sells heads that already have the mods if yours need lots of work(scoggin dickey methinks?)
I hear that the vortec heads flow better out of the box than some of the older performance stuff, but haven't done much research on the topic....
so how much hp to you have to add to the stock 250hp rating to make a minx run a true 70?
if my minx doesn't sell this summer(I hope it doesn't), I may hafta work something up this winter
l8r,
slacker

gcarter
07-23-2006, 12:34 PM
so how much hp to you have to add to the stock 250hp rating to make a minx run a true 70?
slacker
I'd like to know the same thing.
Actually I'd like to be able to run an honest 65 on any given hot muggy day. I really don't have far to go to do it.

smokediver
07-23-2006, 01:53 PM
Did you ever find how the water got in there?
I think you were right about the back of the boat being higher than the front when i flushed it . i am thinking that an exhaust valve wasn't seating right . anyway , there was very little water in there but that's all it takes ! I think i am going to start draining the manifolds afterwards .

need for speed
07-23-2006, 02:07 PM
water ...not gooood.... hey if you need any help let me know.

BUIZILLA
07-23-2006, 03:20 PM
what head casting numbers do you have??

then go here> www.sallee-chevrolet.com

then to > heads

read ALL of the literature, read the valve spring info twice... Crane makes a spring and retainer hit for .520/.530 lift with no machining necessary, if your casting number apply's.

I like the GM LT-4 Hot Cam or a 272ish HMV Comp roller

JH

smokediver
07-24-2006, 06:02 PM
Thanks for the info Jim , i am thinking about the hot cam as well . Charles , i hope to have it running in 3 weeks ! i hope i don't have to bum a ride in 'sota !

BUIZILLA
07-24-2006, 06:17 PM
Smoke, somewhere is a little blurb about using the LT4 cam and maybe needing a cam nose snubber or something like that, on a non LT1 specific setup, since the front cover is different on a non optispark engine, check it out.

JH

need for speed
07-24-2006, 07:19 PM
I hope so tooo.:crossfing . ya always got a ride if needed!!! :wink: