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xm 270 grind reversion? SBC

Old 02-05-2021, 05:28 AM
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Default xm 270 grind reversion? SBC

I have 4" EMI RISERS(and mans) currently. They look like stock shorties like photo. I have a SBC 350 cid. X 2- w/ 64 cc heads and thru transom exhaust. I need to to know if I can run the 270 grind with out reversion?


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Old 02-08-2021, 12:29 AM
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Comp said it would work on a bbc , give them a call
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Old 02-08-2021, 05:39 AM
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Originally Posted by carnutsx2 View Post
Comp said it would work on a bbc , give them a call
thats what I plan on. Thanks for the response.
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Old 02-08-2021, 10:21 PM
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I have done alot of research on that cam. I will be running it in my Formula 272 with vortec heads. It can be run with no reversion on stock exhausts.
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Old 02-08-2021, 10:24 PM
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Fww I ordered one, if its a fail we will all be in the same boat.
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Old 02-09-2021, 05:45 AM
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Originally Posted by 79formula View Post
I have done alot of research on that cam. I will be running it in my Formula 272 with vortec heads. It can be run with no reversion on stock exhausts.
I have 217 casting heads with 64 cc chambers stock. thanks for response.
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Old 02-10-2021, 09:03 AM
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Originally Posted by oconnor marine View Post
I have 4" EMI RISERS(and mans) currently. They look like stock shorties like photo. I have a SBC 350 cid. X 2- w/ 64 cc heads and thru transom exhaust. I need to to know if I can run the 270 grind with out reversion?
You will be fine with that cam grind.
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Old 02-10-2021, 02:40 PM
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Originally Posted by 94sylvan View Post
You will be fine with that cam grind.

these are the units ill be installing when the weather gets better. Jeggs copy of tthe edelbrock high rise without the air gap and 750cfm, marine square bore carbs. the stock heads are unique 217 castings with high compression 64cc chambers. mercury performance 87 o 89 320 efi factory units with center bolt covers(GM made 2 versions. parimeter and centerbolts.) these intakes come with the center intake notched which is the power bump in this design. no airgap which is kinda a gimmic. airgaps when flowing at higher rpm offer no advantage over non airgap notched intakes, I also gasket matched them and will be matching the heads intake openings.

Last edited by oconnor marine; 02-11-2021 at 06:11 AM.
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Old 02-14-2021, 02:00 PM
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The roller cam 270 is biggest for sterndrive. Ie. won't revert with normal exhaust. The flat tappet 270 cam recommends "needs better exhaust"
I think people get a little hung up on the roller vs flat cam.

Also if roller, and you do the Comp Cams CS 268XFI HR13, you get about the same duration and a degree more lobe separation with 10% more lift.

(
Valve Lift .570” Intake .565” Exhaust, Duration at .050 lift, 218 Intake 224 Exhaust, Advertised duration intake 268, exhaust 276, 113 Degree Lobe Separation Angle.)

Runs fine in my boat and SB's


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