Cam selection... I need help
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
CardoO, You have no problem throwing personal insults around. What qualification do you have to give advice beside reading a couple books? The OP has a lot of options with a 3.70 gear and 4 speed. With an automatic 3.08 he would be much more limited. 
Last edited by 63mako; Nov 19, 2007 at 08:51 AM.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Just for information, my old motor ran with 15" of vacuum. Unfortunatly i have no idea what cam configuration it had. But it was still pulling past 6000 so i assume that it was pretty long. Everything on vacuum was working pretty well on that 15". If i recall correctly it had a pressure on the compression stroke of 165...
It would only run well with 12° static advance. Vacuum would drop fast with reduced static advance.
Fuel was what we call lead replacement 98 octane, but it is rated differently than in the US. I believe it is similar to your 93.
To come back to the DCR theorie. I aimed my motor to be at 8/1 just to be on the safe side with the 10/1 static. I believe that DCR has its value. For example I use a cam with a major intensity of 32° (roller) which means it is very agressive. It produces both good idle, low and midrange caracteristics together with high rpm capability. It was a custom grind i used. Originally i used a cam with 278/288° of advertised duration (224/236 @.05 = to small for +6500 rpm use) now i have a cam with the same advertised duration but with 246/256 @.05 Look at it like this : on a compression stroke you keep losing pressure untill the valve is completly seated. Thus the .05 figures don't really matter. However it (.05 figure) does proof to be important on the intake stroke : thus the use for an agressive cam, which provides the above mentioned caracteristics.
Detonation has all got to do with to much pressure on the compression stroke. If you want to be safe you should have a max of 200 psi. Mine has 180. I think it is safe to assume that a dcr of 8.5 would produce somewhere around 200, but it would indeed be borderline.
It would only run well with 12° static advance. Vacuum would drop fast with reduced static advance.
Fuel was what we call lead replacement 98 octane, but it is rated differently than in the US. I believe it is similar to your 93.
To come back to the DCR theorie. I aimed my motor to be at 8/1 just to be on the safe side with the 10/1 static. I believe that DCR has its value. For example I use a cam with a major intensity of 32° (roller) which means it is very agressive. It produces both good idle, low and midrange caracteristics together with high rpm capability. It was a custom grind i used. Originally i used a cam with 278/288° of advertised duration (224/236 @.05 = to small for +6500 rpm use) now i have a cam with the same advertised duration but with 246/256 @.05 Look at it like this : on a compression stroke you keep losing pressure untill the valve is completly seated. Thus the .05 figures don't really matter. However it (.05 figure) does proof to be important on the intake stroke : thus the use for an agressive cam, which provides the above mentioned caracteristics.
Detonation has all got to do with to much pressure on the compression stroke. If you want to be safe you should have a max of 200 psi. Mine has 180. I think it is safe to assume that a dcr of 8.5 would produce somewhere around 200, but it would indeed be borderline.
Last edited by Belgian1979vette; Nov 20, 2007 at 02:44 PM.
