I order the AFR heads with 74cc chamber size to get a 10.39:1 compression

Now the new question graemlins/clonk.gif ,

the cam I was planning to install it got to much lift for the springs I order with the heads ,and another thing it needs 10.5:1-12.0:1 so I need to choose a new cam FOR THE NEW COMPRESSION 10.3:1
The solid xs274 501/510 lift, this cam will be a good choise for a 406 with 10.3:1 ?
the heads are 195cc AFR ,I got a Victor JR intake ,Please help me with this combo

Try either Pat Kelley's great "Effective Eompression Ratio Calculator" site that you get to by his sig. or "Boost Calculator", the second one down on yahoo search page..

AND please read Pat's GREAT site at least 4 or 5 times until it makes since AND I bet you can figure out what cam will be pretty darn close for your application even if it is a program.

Then come back and ask the guys here about what you picked out..

pdq67

After checking THE GREAT Pat Kelly's site here are my #s

8.43 dynamic compression

overlap 57 ,total cam adv 4
quench 44
distance of piston from BDC .7734
SOLID cam is a CC XS 274s-10
274/280
opens close
in 31 63
ex 74 26

8.4 dynamic compression it is ok or is to hight ??

EA3.0 comes up with an effective CR of 7.72, cranking compression of 195, and 10.8" vac at idle. Your compression will be closer to 10.5 if you keep a tight quench. I run my iron head 406 with 74cc chambers, 10.3:1 compression and a 224° cam on 91 octane gas.

I forgot to tell about the .005 piston to deck ,0.39 head gasket ,flat top 5 pistons valve relieve,74cc heads,may be this is the difference in DR ,THANKS ONOVAKIND67 ,all the help you and other can give me will be very helpful .

I can call AFR and may be ask them for a upgrade in the springs to install a xs282 ,244/252
.520/.540 lift

open close .@.015
35 67
79 31
but I am not sure about the powre rpm of this cam and a stock 400 crank
this cvam gives a DC OF 8.1 DYNAMIC COMPRESSION

I ran 8.4 Dynamic on an iron headed 350 with 36deg timing WOT by 3000, 3750lb car, knock sensor picked up no knock with 92 octane fuel.

Being on the high side of the pump gad DCR, its more important to have a good fuel mixture as to not develope hot spots and get pre ignition!

i have red alot on the xe cam line and for some reason all xe grinds are murder on valve train.. not a cam expert but id look towards an isky crower or schnider

Originally posted by rcatala:
I forgot to tell about the .005 piston to deck ,0.39 head gasket ,flat top 5 pistons valve relieve,74cc heads,may be this is the difference in DR ,THANKS ONOVAKIND67 ,all the help you and other can give me will be very helpful .

I can call AFR and may be ask them for a upgrade in the springs to install a xs282 ,244/252
.520/.540 lift

open close .@.015
35 67
79 31
but I am not sure about the powre rpm of this cam and a stock 400 crank
this cvam gives a DC OF 8.1 DYNAMIC COMPRESSION If you look at the cam card, you will find that the advertised duration for the Comp XE solids is measured at .015" tappet lift. At .015" tappet lift and .016" lash the valve is already open, so using the 274 number to determine the valve closing point is misleading.

ONOVAKIND67 you are correct the advertised duration for this cam is .015 tapped lift .that means the cam is at a lower Dynamic compression ??
I am confuse now ,should I ask Pat Kelly for HELP ?? graemlins/clonk.gif

DCR will be slightly lower(how much is impossible to know without knowing the exact cam profile and doing a bunch of complicated math) cause at .016 lash(and i have a xs268-it likes `.014 lash better) the valves are already slightly open before the .015 spec that is given for the adv. #s.

Its all on Kelly's site- http://members.uia.net/pkelley2/DynamicCR.html

6th paragraphy from top.

Wasn't there recently a large pissing match about DCR? In my opinion, it's an interesting thing to know but shouldn't be the driving force behind the parts selection. There are a whole lot of other things to consider about the effects of the compression ratio on the engine build that have to do with resistance to detonation, like quench, swirl, burn rate, cooling efficiency, scavenging, wave tuning, timing, octane, coatings, etc.

The XS274S cam should work just fine in your car.