SBC Marine Cam Specs

[Riley]

I've been doing a ton of research for my 350 Magnum rebuild project, and I'm down to picking out a new cam. I'm 90% convinced I want to go with a Comp Cams Extreme Marine cam, but I don't know which one. Obviously I'd like to get the most power possible, but I don't want to sacrifice the ability to idle along for 15 minutes at a time.

I'm leaning toward the 262 grind, which Jegs lists as having 218/224 duration, and lifts at .462/.477. They also say this is the maximum suggested cam for I/O use, with good mid-range, excellent response, and a noticable idle. 1300-5500 rpm operating range.

Would this be a practical cam for family boating as well as performance boating, or should I go with the 256 grind (212/218 duration, .447/.462 lift)?

The rest of my package includes vortec heads, Performer Intake, and stock marine Quadrajet. I'm leaving the possibility open to upgrading to a Performer RPM, with an Edelbrock 750 cfm square bore marine carb, and GLM exhausts manifolds.

Any thoughts or suggestions would be appreciated!

[BUIZILLA]

I would go with the 256 grind and 1.6 roller rockers.... or the 262 with stock rockers.

J :shades:

[Rootsy]

Sam pilato runs the 262 in his 350.. has a noticable idle but has zero issue with idling at lower rpm and no loading up.

[Riley]

Thanks for the info! The 262 is getting ordered on Friday.

Jamie, you'd think I'd know by now to just contact you directly on any SBC questions I might have. There doesn't seem to be much you don't know in regards to the SBC in marine applications.

Can you tell me what else Sam is running in his combo? Is he happy with the performance of the Comp Cams 262? Any H.P. guestamates?

[jr]

I've got the 262 in a pair of 409's. The power is great, and the idle is good. You won't be unhappy.

[Rootsy]

Chris,

there is PLENTY i don't know about sbc's... PLENTY... Trust me... i am just dangerous :D

Sam runs a stock rotating assembly roughly 9:1 calculated compression, with edelbrock performer heads, the 262, perf eps intake and an edelbrock (Carter) carb... along with a TBolt IV ignition and SM exhaust... guestimates would be in the 350 - 360 hp range at the crank...

PBM also makes a very similar hydraulic, at least on duration figures but lower on lift, that makes some good ooomph... mr allard is running it in his, AHEM, "stock" 350 in the neighborhood of 400 ponies... or at least that is the cam card i saw once... :cards: but he has some serious cylinder head and intake to help it along...

224 degrees of duration @ .050 is about as much as you want to push the envelope if you are running stock exhaust AND IF you EVER run thru-prop with that exhaust.. straight thru-hulls are a wee bit more forgiving in the reversion department... but not much... anything more than this rough guideline and you best be dumping the water further back in the riser...

also, if you ever plan to swap to 1.6 ratio rockers on the vortec or other stock cylinder head pay close attention to pushrod to cylinder head clearance where the pushrod passes through the head... you generally need to open them up some... i can speak from experience on this one...

NOW if you wanted to go roller cam i have an XM264HR all sealed up taking a nap... just ready to be awakened again ;)

[Riley]

Darn it, Jamie! I think I've got my mind all made up, and then you have to throw that roller cam option at me. As tempting as that sounds, I think I'll stick with the regular hydraulic cam for the time being. Simpler and cheaper, all the way around.

What's the difference between the standard Performer and the Performer EPS? Isn't it plenum height?

If I could get 350 cshp out of my new combo, I'd be very happy. I'm sure the limiting factors will be the Performer/Quadrajet and the stock exhausts. However, by stock exhausts have the 3" riser between the manifold and the elbow, so that should help a bit. Plus it's a straight shot out the back, with no mufflers.

[MOP]

Jamie finally got the cam specs ferreted out, its a Comp Hyd roller, I am going to use the 1.5 rockers for now and leave the 1.6's on the shelf. Would you set this at the recommend 108 or pull it back a few degrees?

Lobe number 3109
Lobe lift 341
Rated duration 176
.050 @ 220
.200 @ 137
Rocker arm to ratio lift
1.5 .510
1.6 .544
1.7 .578

[Cuda]

I tried to look up what cam I used. I saved the crane webpage, but they must have changed it, and now I can't remember what it was. I think I used the same one as Forrest.