The DCR number is strictly a reference number we use to determine the 300 sixes tendency towards detonation and it also has relevance to the cranking compression.
We developed a DCR range for the 300 six based on engine build history using the .006" intake lobe closing point.
Any other lobe lift point is meaningless as far as detonation is concerned for the 300 six.
The Cam card I posted shows a .006" (advertised) duration of 268 degrees and a 114 degree LSA.
The .050" intake opening at -5 degrees and closing at 35 indicates the cam is to be installed 4 degrees advanced with the intake lobe center at 110 degrees ATDC.
That puts the .006" closing point at 268/2 + 110 -180 or 64 degrees ABDC.
All timing events are on the card using a little math.
So you would use 64 in the calculator to figure DCR.
The DCR should calculate as 6.6
The Felpro 1024 head gasket has a bore of 4.18 and a .039 compressed thickness.
Got it, this is based on historical data. That makes a lot more sense.
Also I don't have much experience in this realm, so I didn't know that advertised duration was equivalent to "duration at 0.006 lift". Thanks for clarifying that.
As it turns out, the GFM calculator might have an error in a formula somewhere. Putting in all the above values with a valve close at 64° and piston volume of 30cc, it turned back a DCR of 5.85 and not 6.6. This is a good lesson in putting trust in online calculators when you can't see the math working. After going through all the hand calcs, I arrived at the same 6.6 DCR
The two numbers I calculated was 18.9 CC to get a DCR of 7.25, and 30.8 to get a DCR of 6.6. Pmuller, you are saying 6.6 would end up being a good way to go on this build? I can calculate theoretical bests, but I'll trust your empirical recommendations.