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

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

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!

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

I can see I'm making everyone uncomfortable.

There, that's much better.