I was waiting for someone to ask about the convertor and gearing, cuz you know gearing and stall is paramount to a streeter. And also talk about cylinder pressure.
My opinion is this; the best you can get, reliably, with 63cc heads and zero deck is about 10.8 Scr, and when you switch to aluminum from iron, yur gonna need about an extra full 1.0 Scr just to make the same power that you were making with the iron. I know smarter men than me will argue this, but the dyno ain't the street.
If that is true, then for the aluminum heads to break even on material alone, then your current combo would need to be at least 9.8Scr right now. So if yur still at 8/1 this is a lost cause, and so spending big bucks on aluminum to gain the compression is a waste of money, even if your current Scr was 9.8
Further more
if you did have 9.8 with IRON, and did pump it up to make 10.8 still with IRON, and made no other changes, then you could expect a power increase of just 1.5% or so. Now recall that the power increase comes at high rpm and is over a very narrow rpm range. This reflects nothing on what is going on at sub-peak rpms.
Ok so now lets say, for argument's sake that you currently have about 300 hp and it's peaking at 4800rpm. With 2.94 gears,26" tires,and 5% slip in the TC, this will be ............................. 49mph. You see the problem? The power will begin at about when the torque peaks, so in this case about 3300 .................. at 34 mph. You got a lotta driving to do to get onto the bottom of the powerband, and a lot more to get to the peak.
This makes the engine SEEM weaker than it is.
Next is the current TC which you don't know much about, so let's be generous and call it a 2200 stall. So when you punch it from a stop, the Rs will rev up to 2200. If you imagine your torque curve, you might see 220 ftlbs there. So, to the road, this would be 220x2.45(1st gear)x2.94(rear gear) is 1585 ftlbs into the rear axles which is barely enough to squawk the tires , am I right?
But by 3000 you'd be coming up to the torque peak, so if you had a 3000 TC and if your engine was making 300ftlbs there, and say you had the 3.23s, then
300x2.45x3.23=2374 ftlbs which is 50% more torque into the axles. Fifty per cent more!
Same engine.
I'm guessing at the numbers for illustrative purposes but your results could be similar.
The 3.23s will bring 3300 down to 31 mph (from 34), and down to 45 (from 49). still not really impressive, but what can you do when hiway cruising takes precedence...
As can be seen, the bigger TC makes a huge difference.
and in your case the TC is the first thing I would change.
Say a 2800. This will make a huge difference in the personality of first gear. The 3.23s will make subsequent gears feel 10% stronger, but you will be spinning thru most of first gear now,so the 3.23s might get lost in the tiresmoke.
And my opinion is to not be in a hurry to change the cam. With no other changes, a later-closing intake valve will make less cylinder pressure, and you will feel this as a loss of power in the lower, sub torque-peak rpms .............. exactly what you don't want, with the stock TC and 2.94s. More power at some much higher rpm is probably not what you want.
These are my opinions.
Now, if you really want to wake that engine up, get you something like 3.91s .............. but forget about daily hiway cruising, cuz 65~3300 at zero-slip. There's no free lunch. If 3300 is to much, get you an overdrive. The A500 will get you a .69od gear, reducing 3300 to 2280 in lock-up.
And still same engine.
