Made a few pulls today on a 426 wedge. The motor initially made 380 hp a few weeks ago. I thought it should do better so I pulled it down to see how it was setup. The motor started out as a 413 truck block, was bored to 4.25", my friend screwed the motor together with so e-bay parts. low compression max-wedge pistons, comp cam solid .525/.525 lift, 516 heads, torquer intake. After checking I found the compression was 8.44-1, I had a set of 452's I'd milled .100+ and installed them to bring the compression to 9.4-1. No other changes it responded on the first pull by going 412hp&469ftlbs. I then pulled the torque intake and installed a M1 single plane. The M1 picked it up to 417.6hp&480.4ftlbs. I then installed a 2" open spacer and it went 427.1hp&487.5ftlbs. All pulls were using a holley 850 double pumper, no carb tuning was done, A/F ratios were in the high 12's to low 13's. Some hp was probably left on the table as I was still running 100+ octane fuel.
Next up will be a thermoquad.Dave

Pretty healthy numbers considering.I would love to see an rpm intake on it(easy for me to say) for comparison.

Pretty cool Thanks for posting

I did a bit more testing with the mule the last few weeks. I tried a modded up 850 thermoquad and got within 10hp of the 850 holley. The carb did not like the adapter at all. I made up a spreadbore plate to bolt up to a 4500/4150 adapter and it made things even worse dropping the hp down to 405.
Pulled that off and reinstalled the 850 holley with the 2" open spacer. 38 degrees timing REAL 91 octane fuel, 9.4-1, 452 iron heads, M1, .525 comp cams solid,1-3/4" no name headers number shake out as such;
440.2hp@5171rpm
489.8ftlbs@4481rpm
Engine only was using 640cfm at peak hp and pulled 690cfm 500 rpm over peak hp.

The first pulls on the motor as delivered were 380hp and 465ftlbs.At this hp level it was running 12.80's in a 3800 RR bracket car.Dave

Thanks for the very informative update. I actually picked up a 426 Wedge short block with some domed pistons that I was going to do something along your build with maybe a bigger bumpstick.