Anyone using Big Chiefs?

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03-05-2009 | 08:56 AM

#21

Panther

Frank's Marine Service

Joined: Sep 2002

Posts: 11,959

Likes: 142

From: Elkton, MD

Quote:

Originally Posted by KYElimEagle

Frank,
How did they run? What RPM's were they turning. Kurt says use the heads, with newer cam profiles he has had good performance and longevity. Cam was solid roller .714, 266 intake and 270 on exhaust, crane 13519-16. Not much ramping very rapid open and close.

They were pretty stout engines. Pretty sure they idled between 1000-1200 rpms. They pushed the boat, 87' Flat-Deck Top Gun, to 80+ mph. If memory serves me correctly they were turning 6000-6500 rpms WOT.

With your size motor I've seen a lot of guys running the Crane 139651 which is fairly mild. As I stated earlier, I'm running a solid roller cam in my 580" blower motors. I'd have to double check my cam card but I think I'm running the Crane 138641. I adjust the lash once a year and I'm also running .016 lash instead of the .020 lash they call for. They Idle about 950-1000 rpms, never stall even if it's a quick shift.

I'm not sure if those cams will work with your heads but they're cams that have decent ramp speeds without crazy lift.

Frank

Last edited by Panther; 03-05-2009 at 09:06 AM.

03-05-2009 | 09:01 AM

#22

BenPerfected

Platinum Member

Joined: Dec 2002

Posts: 2,195

Likes: 2

From: Dallas, TX

idanc1,
I would be interested in more info on the the combination where the 520 CI NA motors made 1100+ HP.
Ben

03-05-2009 | 11:55 AM

#23

vtec

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Joined: Mar 2002

Posts: 369

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From: Sterling Heights MI

Is this how you make BC's last.

Jesel

http://www.hotrod.com/techarticles/e.../photo_11.html

03-06-2009 | 09:01 AM

#24

40FlatDeck

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Joined: Dec 2006

Posts: 495

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From: Tucson, AZ

Quote:

Originally Posted by vtec

Is this how you make BC's last.

Jesel

http://www.hotrod.com/techarticles/e.../photo_11.html

Hmmmmm, very nice. Ti valves-check, Bryant Billet-check, Jesel valve train-check............

03-06-2009 | 11:10 AM

#25

PatriYacht

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Joined: Jul 2002

Posts: 2,867

Likes: 3

From: Waterford,MI

I hear the way to make them last is to change the valve springs every 50 hrs. if your cam is in the .700 lift area. More often if the lift is higher. Much more often. Also the offset rockers have to be inspected regularly. The geometry puts a lot of stress on them. Not worth the trouble to most people.

03-06-2009 | 05:26 PM

#26

GPM

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Joined: Mar 2004

Posts: 2,697

Likes: 93

From: Pa

So how much power do you lose going from a solid roller to a hydraulic roller keeping the same duration at .050 . What's the RPM range of a hydraulic roller?

Last edited by GPM; 03-06-2009 at 08:10 PM.

03-06-2009 | 06:41 PM

#27

RunninHotRacing163.1

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Joined: Sep 2007

Posts: 12,849

Likes: 3

From: Frankfort,ill

[QUOTE=PatriYacht;2815515]I hear the way to make them last is to change the valve springs every 50 hrs. if your cam is in the .700 lift area. More often if the lift is higher. Much more often. Also the offset rockers have to be inspected regularly. The geometry puts a lot of stress on them.

So ya think so ???? mmmmmmmmmmmmm

03-06-2009 | 07:19 PM

#28

SkiDoc

Thread Starter

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Joined: Oct 2002

Posts: 2,059

Likes: 96

From: Bowling Green, Kentucky

Bill,
What kind of set up are you doing with your Chiefs?????

GPM,
Jim Valako told me that the weight of the valve train is heavy and one hydraulic motor that he did started to float the valves at 6000 rpm. which would be right when the large ports start to become the most efficient.