The ported Mummert aluminum heads have now been dyno tested on the 375” EMC engine and after the noise abated, was rewarded with a 52HP increase over the ported iron 113 heads that were used in last years EMC competition.  Both sets of heads were tested on the same day to keep weather variables out of the mix.  There’s still a bunch of tuning yet to do but this was a nice improvement for just a head swap and minimal tuneup work.  Total timing for the iron heads was 39° while the timing for the aluminum heads is 32°.  Distributor curve is currently the same for both heads but in looking at the data, the aluminum heads look to prefer something different in how the curve is applied.  This will be worked out when testing starts back up.  Shop temperatures were in excess of 100°F so consider this race day tuneup stuff.  And remember this is still a street engine that’s running on 91 octane gasoline.

In the mean time, here are a pair of graphs which do more in telling the whole story in lieu of just typing out a bunch of numbers.

Looks like you bumped the Y block to over 500hp By a bit A big bit

Congratulations on achieving the goal of making a 500hp Y block. 

PS: when your done testing the heads, now that they are "used", can I have them!