Mercruiser SBC350 Camshaft

[LiquidAssets72]

Hey all, I am looking for some advice on camshaft choice for an engine I am building. This engine will be used in a 21' open bow Arriva. Engine is a reman 70'-79' Chevrolet 350, built using all OEM spec marine parts. Will be running stock spec perimeter bolt heads. I am looking to slap a cam in it before installing the engine and was hoping for some advice or input. Will I need to worry about new springs, lifters, or anything else?

Cam I am looking at is the Comp SKU 12-236-3

Adv. Duration Int/Exh: 262/268
Duration @ .050" Int/Exh: 218/224
Intake Valve Lift: .462"
Exhaust Valve Lift: .477"
Lobe Sep: 112

 

[Scott Danforth]

what are "good OEM spec marine parts"?

you mean the marine stuff bolted to the outside, or the stock GM truck parts that make up the long block? the stock flat top pistons with the 4 reliefs?

the XM268H is a good cam, however not needed with stock drive, stock wet exhaust. what drive and exhaust are you planning on running? Alpha drives dont like much over 5000 RPM

I ran the XM262H on the Rogue (see first post of link in sig, from there is post with cam and head change)

Venturing into performance upgrades for an AQ271C

Have an 88 AQ271C with a DP290 drive. now the quest for more power. going to take this in phases: update stock, simple bolt-on mods, then ??? plan is to get the boat to 50+ starting to stock-pile a few parts. first things - simple carb go-thru. new power valve, gaskets, and maybe play...

forums.iboats.com

yes, you need new springs and any flat tappet cam requires new lifters (all flat tappet cam lobes and lifters are mated for life)

so if you didnt mark which lob the lifters were on, you throw away the old cam and lifter anyway.

suggest vortec heads over the stock 70-79 heads. you still need to modify the seals for anything over 0.420" lift on the vortec heads

 

[LiquidAssets72]

what are "good OEM spec marine parts"?

you mean the marine stuff bolted to the outside, or the stock GM truck parts that make up the long block? the stock flat top pistons with the 4 reliefs?

the XM268H is a good cam, however not needed with stock drive, stock wet exhaust. what drive and exhaust are you planning on running? Alpha drives dont like much over 5000 RPM

I ran the XM262H on the Rogue (see first post of link in sig, from there is post with cam and head change)

Venturing into performance upgrades for an AQ271C

Have an 88 AQ271C with a DP290 drive. now the quest for more power. going to take this in phases: update stock, simple bolt-on mods, then ??? plan is to get the boat to 50+ starting to stock-pile a few parts. first things - simple carb go-thru. new power valve, gaskets, and maybe play...

forums.iboats.com

yes, you need new springs and any flat tappet cam requires new lifters (all flat tappet cam lobes and lifters are mated for life)

so if you didnt mark which lob the lifters were on, you throw away the old cam and lifter anyway.

suggest vortec heads over the stock 70-79 heads. you still need to modify the seals for anything over 0.420" lift on the vortec heads

I'm not entirely sure. It is a stock spec marine 350 from a local marine engine rebuilder.I bought the boat, and discovered that it had an older 350 with later 305HO heads in place of the 89' Mercruiser 5.0. So I ordered an older 350 with stock heads, rather than deal with the high compression of the HO small chamber heads etc. Trying to be able to bolt up as much of my accessories as possible and not have to buy a lot of new parts. I was just curious if it would be worth installing something like this cam or better of keeping whatever they send it with in it.

Exhaust is a stock wet-riser set up for now, considering installing a captains call with side-exit thru-hull tips however behind that.

Will probably stay stock on the cam unless anyone has a great reason not to. If I'm not gonna see much power gain without head work, or something like that then ill leave it alone. Even with a stock 350, I'm sure I'll be putting down significantly more power than the original 5.0 was.

Currently has a quadrajet on it, and an automotive performance products polished intake which I am going to more than likely change for something marine intended or at least not polished because it sticks out like a sore thumb between the black engine and black carb. Lol. Any recommendations on intake manifold for spread-bore quadrajet and older gen 350?