Leathl_WS6

Ok I have done a lot of searching and reading on this topic here on OSO but can't find the info I need. I'm building a pair of 502's 9.5:1 RPM or Air Gap intakes. GM Rect Port heads pocket ported and valves have been deshrouded. Exhaust for now is a manifold with riser water dumps outside of the transom so reversion should not be a problem. What I would like to run is a 230 238 on a 110 or 112 LSA but I can not find a grind like that. So these seem to be my best choices. Which would you run.

Comp XM278H
intake 234 564
Exhaust 244 567
LSA 112

or

Comp XM270H
Intake 226 544
Exhaust 236 547
LSA 112

Any other suggestions would be great as well. I want a 110 to 112 LSA for sure.


Thanks Rob

WAGS382

Rob,
I have been reseaching cams for my 502 also and this is close to what you want,
Crane 761 230*in 236*ex .598 .610 112*lsa . I will have some HP500 parts for sale soon , cams, ignition moduals, heads. I know of a set of used 761 cams, new condition, pm me if interested.

Leathl_WS6

Thanks wags but for as cheap as cams are I don't think I'd take a gamble on used ones. I did see that cam the only thing I didn't like was the big lift. Seems like it would wear out springs quick. What kind of results did they get with that cam?

Rob

Griff

Those look like flat tappet lifts. Why not use a Crane 741 roller and make more power???

RLW

I suggest that you contact Bob Madara (aka. RMbuilder) on this board and have him custom spec a cam for your application. I have been fortunate to have spent some time with Bob. This guy is brilliant when it comes to valvetrain selection and setup.
The marine market is very specialized. The component manufacturers are geared to the automotive market. Bob has the knowledge for what it takes to have a successful marine engine.

mcollinstn

why such a tight lobe center? You gonna circle track race it?

Leathl_WS6

I was going to go that route but. I'm running TRS drives with Merc Trannys. So about 500hp is all I want. Roller drivetrain would probably net me over 500 and would cost me about 600 more a motor. Just trying to keep cost down a bit.

Leathl_WS6

I will try to get a hold of him thanks...

Leathl_WS6

Thats funny... Nope no circle track. I have gone from a 114 to 110 before in a 468 lift and duration being similar there was a big difference in power. the 114 is a smoother transition of power. But seems to me overall performance was way better with the tighter lobe sep. Stock mercruiser cams are 114 lsa main reason they run them that wide is chances for reversion with a tighter lobe sep. Dennis Moore actually suggest a 109.

Plus they sound way better than a 114 or higher.

KAAMA

Leathl,

Reed Cams makes a hydraulic roller 232*/238* @.050" lift (284*/290* advertised) .578"/.578" lift all on 112* lobes. In fact I have a pair of these cams right now and they have NOT been used and are made for a Mark-4 block. I paid about $250 each for these cams. I will sell them to you for $230 each if you like. Otherwise, I believe at least one good person to consult would be "rmbuilder" aka Bob Madara concerning cam selection.