another head, cam suggestion, post

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01-03-2006 | 12:37 AM

#21

JJONES

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Joined: Nov 2002

Posts: 708

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From: SOUTHERN CALIFORNIA

Re: another head, cam suggestion, post

Sorry about my last post,I must have some setting anabled that changes all the letters! Sorry it was so hard to read!

01-03-2006 | 12:28 PM

#22

KAAMA

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Joined: Oct 2000

Posts: 4,541

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From: Western Michigan

Re: another head, cam suggestion, post

Rookie, the Stainless Marine exhausts are fine....and about the same with the GILS as far as performance goes. And like I said, that's money you DON'T have to spend! By the way, I would have to say that adding an additional 125hp per engine should push your 30' Scarab faster---how much faster remains to be seen, but it's always harder, and takes more HP to go faster in a boat anyway. Of course it's always worth hearing experiences from others, but you're ultimately the one who has to decide it's worth doing.

01-04-2006 | 12:05 AM

#23

formula31

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Joined: Mar 2001

Posts: 2,558

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From: ohio

Re: another head, cam suggestion, post

Quote:

Originally Posted by Rookie

I have Weiand stealth dual plane intakes and was thinking of upgrading. I have no issues with low and midrange twins in a relative light boat. but at 5000 rpms it hits a wall, it takes forever to get that extra 200rpm's.

Dont discount those Weiand Stealths so easily. They are way underrated. I ran a pair of real healthy 560 hp engines with them up to 6000 rpm and they did fine. Actually did better than the dart single plane up to 5400 (and idled at 600 rpm, the dart wouldnt).

01-04-2006 | 08:20 AM

#24

cstraub

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Joined: Jan 2005

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From: Tri-Cities, TN

Re: another head, cam suggestion, post

Quote:

Originally Posted by Rookie

Thanks Chris, that is what I wanted to hear about the heads. Do you believe that stroking these engines, with a cam change, and the existing large rectangle bowl ported heads chevy heads will be over the 500-525hp range? you still haven't brought up a cam selection that you would feel would work for these mills, the 731 does sound like a good choice. would I have to worry about piston clearance? I know my heads are 118cc, but they have been milled down to 114.5cc. the compression is high 175lbs on one engine, and 185-190 on the other..

The OEM heads vary on the castings with core shift quite a bit and this effects flow. So I don't know what your heads are doing. General rule of thumb though out of the box you need about a 10 to 12 degree split crutching the exhaust. BBC are very forgiving as far as Piston to Valve clearance so PV should not be an issue.

Intake on your mill I would go an air gap.

02-05-2007 | 12:16 AM

#25

turbo94gto

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Joined: May 2006

Posts: 187

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From: Scottsdale AZ

Re: another head, cam suggestion, post

I am doing the same setup on my boat right now. With the same heads. But I am putting reflashed 502 mpi injection setups and stellings headers. did every decide that the 731 cam was the ticket?