Help on 408 build
So this wouldn’t be a good idea unless I can get another 5ccs of of the chamber? Or it would and I wouldn’t be happy with the end result? Only reason I want to go this way is to stay away from touching the short block.
As you say, it can be made to work, but the operation will be something like what I outlined above and is a setup that you may or may not enjoy. Getting down close to 10:1 static CR is the max CR you would want to be for a cam for 'smoother' street performance, pump fuel, etc.
The heads you show are really to achieve mid to high RPM flow and are more for high performance so great for making more high RPM HP on the drag strip. But you may be just as happy with smaller flowing heads for street use if you never get to the high RPM's much. Smaller heads are A-OK with me as I am more interested in good street operation and a smooth, wide torque curve than raw peak HP; I am not a drag racer.
Since the smaller heads have the same chamber sizes, the high static CR problem you have still does not change. Options to lower the CR:
- Different pistons as discussed
- Bigger head chambers, which none of the AL heads achieves. I am not aware of any AL heads with chambers larger than 65 cc.
So you either go with iron heads with bigger chambers or use some AL heads and have the chambers opened up. Some would cringe at taking a new AL head and having them hogged out! I'd want to get something like
at least 8 cc's out of the chambers here and more like 10 cc's; I have taken 8.5 cc's out of open chamber iron heads for exactly this purpose (lowering SCR). Whether that can be done on closed chambers like on the current crop of AL heads, I can't answer; I'd be a bit hesitant to try.
Another choice to get larger chambers is to go with stock iron heads. Yours have been milled heavily and that is the main source of the small chambers and the high CR problem. Get some stock iron heads and have the chambers set to around 74-75 cc's (And you could go even bigger) and you are most of the way to managing this. You still need a slightly larger cam, but not a big cam change like for the AL heads so engine performance can be kept closer to street.. if that is what you want.
Not sure if this helps you or not!