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What's the difference between marine vs street cams?

30K views 5 replies 5 participants last post by  jtm60 
#1 ·
I have noticed cams for BBC that have great specs that are labelled for marine use. For example Comp cams Extreme Energy 11-236-4, 270/286, 226/236@0.050, .544/.547 lift, 112 LS. It would seem to fall between a XE268 and XE274 for street use. In computer simulations the latter cam makes good power and torque. It's usage is designated as for Jet boat with "A" impeller. Is there some aspect in the design of these cams that makes them unsuitable for street use? Has anyone ever tried the latter marine cam in a street vehicle?
 
#2 ·
Caplin,

Actually, it's the other way around.....
Most 'street' cams aren't suitable for marine use.
Because of low-speed docking needs and the problem with water entering the exhaust in low-vacuum engines, most marine cams are on 114 or 112 LSA. These work just fine on the street if you want a smoother idle and more vacuum, as well as a flatter torque curve. Many street racers don't, they want the lumpy idle and tremendous mid-range torque, and they use 110 LSAs, and even 108 LSAs.
The old UD BB288/296H10 was designed for Mercury Marine, they bought about a 1000 or so, until the 502 cam out. It was on a 110 LSA, and was at the limit for docking. Going 8° larger at .050 meant that you had to use Rhoades lifters to be able to dock. Vacuum was no problem because the engine did not use an underwater outlet.
Many of my marine cams are made on 114 LSA....

UDHarold
 
#3 ·
Some info that I picked up - Marine cams use gentler lobes for longevity. IE - a 454 or 502 big block set up in a boat might run at 4500 RPM for hours at a time. That's equivalent to taking your 4.10 geared big block Chevelle down the highway at about 90 MPH without stopping.

For what it's worth, I personally like the Marine cams for street use. Just aggressive enough to make good power without all the extra wear.
 
#4 ·
I know guys who have run marine engines on the street and they run sweet. The Bozo who decides he is going to a killer engine, like he built for the street in his boat has problems. Marine engines need to run at idle for extended periods of time and NOT stall or foul plugs. Some areas may have a No Wake Zone that requires 1 hr at or above idle. Boats regulate engine RPM by prop size or jet size. Larger the prop or pump lower the RPM will normally be. A good stock combo will stay under 5000 rpm at wot. And for how hard they run try 90mph towing a trailer uphill is the equivelent.
 
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