540 build cam selection with gil exhaust
#22
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Those heads are way to little. I ran them on a 439, and they were an awesome head. On a 540, it would be one of the last heads I would pick, and no way you're going to make power to 5800. Those heads are hard to find used and you could sell them at a premium due to that. Why not sell them and get the proper head? 265 for a 540 IS NOT the correct head.
#25
Charter Member#568
Charter Member
They're quite a few lengthy threads here about optimal heads / carbs for a 540. Whether or not to even use AFR is likely to be a lengthy discussion.
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Straight bottoms and flat decks
Straight bottoms and flat decks
#26
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The 290 and 300 ovals, 305 and 315 rectangles are all great heads. I'm not an engine builder, so I'm not suggesting anything other than the 265 is just a little head, and it was designed for a 454. A 540 is WAY bigger than a 454. Say it cost you an extra $900 or less to do it right, then I would do it the right way. IMO you are leaving a lot of power on the table with that tiny head. If I was building my 509's from scratch I would be running either the 290 or 300 ovals.
#29
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I agree with the above. 265 , with a 2.19 valve, is gonna limit power. You'll make some big low rpm torque, and lack upper end power. It will allow you to run a really tall pitch prop, add some extra stress on your outdrive, and probably accelerate like crap, since it will be like running a 3.08 rear end, vs a 4.10 rear end. Theres a reason nobodys really running diesels in FAST offshore boats.