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Goto 540 or Tweek out the 489

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Old 05-02-2022, 06:45 AM
  #21  
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I’d guess about 40 hp or so going up 10* and similar lift.
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Old 05-02-2022, 10:44 AM
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Originally Posted by SB
I’d guess about 40 hp or so going up 10* and similar lift.
There were a some custom Bullet roller grinds in the swap not long ago that would be something to consider. If I recall their pretty close to what I’d be looking for with that CI combo.
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Old 05-02-2022, 11:02 PM
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I just read about a thousand post on failed Marine Kinetics cams. Now I am nervous. I did not have a catastrophic failure before my rebuild and it did hold up for several years. But I did have a ton of valve leakage on the leak down test before rebuild. I had 8 rocker arms that needed rebuilt. Not sure if they were exhaust or intake. I was burning at least a quart of oil per day trip at the end. I am now getting regular oil analysis and this should give me a heads up. I had at 4 of them done last year and it was better after I added the oil thermostat. Any advise?
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Old 05-03-2022, 06:58 AM
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More round table talk….

Another note: if you are truly at 10.3:1, the cam you have is too short in duration. The cam you have was trying to achieve more cylinder pressure , which you don’t need nor want now.

Note#2: You where reving 5500rpm. My guess is that was just passed max power. 224 is a tow truck cam for near 500cid.

Somewhere 236-240 at .050” intake duration is where your motor will want to eat. Prob 240
You have an exhaust to handle it?
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Old 05-03-2022, 07:47 AM
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The last 496 builds I had custom comp grinds.

244/248 with dart 310 cc heads. Peaked at 6k. Just a reference….
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Old 05-03-2022, 07:50 AM
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Originally Posted by getrdunn
The last 496 builds I had custom comp grinds.

244/248 with dart 310 cc heads. Peaked at 6k. Just a reference….
What compression ?
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Old 05-03-2022, 10:06 AM
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Originally Posted by SB
More round table talk….

Another note: if you are truly at 10.3:1, the cam you have is too short in duration. The cam you have was trying to achieve more cylinder pressure , which you don’t need nor want now.

Note#2: You where reving 5500rpm. My guess is that was just passed max power. 224 is a tow truck cam for near 500cid.

Somewhere 236-240 at .050” intake duration is where your motor will want to eat. Prob 240
You have an exhaust to handle it?
Ran a 24 pitch prop 5500 RPM with old setup, now using a 25 pitch to the same RPM, going to try a 28p Bravo prop this weekend. I have 113CC heads with a small dome piston, including the gasket thickness I have 10.3 to 1. Eddie Marine exhaust with long wet risers.

Last edited by jeffswav; 05-03-2022 at 10:11 AM.
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Old 05-04-2022, 10:38 PM
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Anyone have experience with this cam?
https://www.cpperformance.com/p-1675...-camshaft.aspx
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Old 05-05-2022, 12:22 PM
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Originally Posted by SB
What compression ?
Aluminum heads 10.5
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Old 05-05-2022, 12:26 PM
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Originally Posted by jeffswav
Anyone have experience with this cam?
https://www.cpperformance.com/p-1675...-camshaft.aspx
No but I like it. Very similar to mine with a little less lift but not much… like .013 less + -
This would be a little easier on VT

623 hp at 6k on my 496’s - same duration!
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