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4 Cam Profile

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ironwigwam

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Posts: 124

Joined: Sat Nov 20, 2004 1:01 am

Location: Glenmoore, Pa. USA

Post Mon Dec 31, 2007 6:21 am

4 Cam Profile

Everyone knows that exhaust cam lobes ususally have a longer duration in cars than the intake. Converting this info to Indians, I am having the exhaust cam lobes for a 4 cam set up being made with a longer duration than intake, Just how much, 4 degrees, six degrees? is my question. I have CAD drawings using 6 degrees to help in scavenging the gases out of cylinder.
Does anyone know different?
Rocky
1957S/VG
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ironwigwam

User avatar

Posts: 124

Joined: Sat Nov 20, 2004 1:01 am

Location: Glenmoore, Pa. USA

Post Wed Jan 02, 2008 5:51 pm

Re: 4 Cam Profile

Ok, it is a moderate Hi Rpm so it stays at 6 degrees, just as I thought
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101 Fan

Posts: 10

Joined: Sun Aug 21, 2005 3:58 am

Post Fri Jan 04, 2008 8:13 pm

Re: 4 Cam Profile

What about compare with other flathead engines as in Go-Karts and tractor pulling engines and see what you find? I'll bet they are up to the tuning state and revs your aiming at. There sure are some interesting sites about that. Otherwise there is only the seriously racing road racing FH HD's I can think of that are a starting point to go from?!What did Bert do? Oh I almost forgot he went OHV and Methanol ;-/. Do you have any cam charts from him? Would be a thrill to see his shelfs in Invercargill!
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ironwigwam

User avatar

Posts: 124

Joined: Sat Nov 20, 2004 1:01 am

Location: Glenmoore, Pa. USA

Post Sun Jan 06, 2008 6:09 am

Re: 4 Cam Profile

Burt and others used the same lobe as on the intake side and never got a more defined lobe center angle. I am going to try to increase the effect of the ehaust gases scavenging nore intake charge thru a faster velocity in the ports using the gas charge.
Here is one of burt's 4 cam lobes, a modified bonneville profile. You can see the seperation is the same and I beleive could be improved, not sure, might be wrong?
http://img.villagephotos.com/p/2005-11/ ... set-up.jpg[imghttp://img.villagephotos.com/p/2005-11/1109362/4camset-up.jpg][/img]
Not sure the photos are showing upo, better read the instructions
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panic

Post Wed Jan 16, 2008 11:42 am

Re: 4 Cam Profile

I can see I'm making everyone uncomfortable.

There, that's much better.

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