To recap, 390 in my Merc needed to be cleaned up as years of leaks/spills/etc had it looking pretty ratty. Stumbled on a deal for BBMs and a hydraulic roller that matched my needs so decided to update the motor while I was at it.
Old combo:
Holley 750DP
Performer RPM (untouched)
270H (224/224 .519/.519 110LA in at 102ICA)
1 3/4" Tri Ys
9.1:1 CR
Edelbrocks with bowl and port entry cleanup and good valve job
Engine ran well, plenty of lowend, did 300rwhp with good AFR and 37* timing. Ran "OK" but honestly for the parts involved, never felt it was that strong. I thought maybe there was an issue with the combo, but Barry tested basically this same exact combo and made ~365hp on his dyno which jives pretty well with what mine made in the car so figured there wasn't much more to squeeze out of the combo with tuning or easy parts changes.
New Combo:
Holley 750dp
Performer RPM (plenum entry rolled, port matched, bullnosed the plenum partition)
Survival hydraulic roller 224/230 .563/.563 110LSA 104ICA
1 3/4" Tri Ys
9.2:1 CR
BBMs with 2.09/1.65 and light seat blend
Finally got it in the car and ran it last night. Obviously the cam is similar, but audibly and driving it gently around town, I basically can't tell a difference. It may be a bit crisper down low at part throttle which is impressive as the car always had tons of lowend. Also the valvetrain is quieter, can't say for certain this is cam/lifters as I spent more time setting valve geometry, but it's definitely quieter.
Punch it from a dead stop, better response, not exponentially but it now has traction problems whereas before it would dead hook. Midrange, honestly, feels about the same. 4000rpm and up, definitely pulls harder and seems to easily pull to 6000. Previously it would flatten over 4500, and sort of labor to 5400 or so. It's not a wholesale change, but just pulls cleaner up top now.
Here's the interesting point, I had both sets of heads flowed on the same bench. I'm apprehensive to do this because the numbers are low compared to full database of what I have for similar heads and guys are going to just look at the numbers....all I care about is the difference between the two ON THIS BENCH. It's a Superflow 600 bench, but both heads I had done were down ~15-20cfm in the .400-.600 range compared to other records. The BBMs were done by Brent, my Edelbrocks were done by a very competent builder in PA and this wasn't extensive work on either, and plenty of comparisons for each head so I'm confident that this is just a case of that particular bench being conservative.
My BBM Cyl1 2.09
71 58
148 105
204 141
240 170
258 189
277 208
291 216
AVE 212.7 171.5
My Ebrocks
79 69
148 114
180 155
218 185
248 206
255 211
257 217
197.9 165.3
The Edelbrocks are more extensively ported than the BBMs.
Should be interesting to get it on the chassis dyno and see how the curves compare, I'm guessing about the same until 4000rpm, then the BBM combo maybe 30hp stronger at peak and carrying much better past peak. Need to get it to the track in the Fall and see how it does, hoping low 13s but not sure I'd be confident it will get there.