427SO Blue Thunder motor dyno #'s

[dlampe]

Let me share my build first.
.017 over 68 sideoiler
stock crank, H-beam rods, JE dome pistons 9cc shaped to fit combustion chamber, 13 to 1 comp.
Crane cam solid flat f-252/3574 lift at the valve 629,640 adv dur 288, 292. I think 108 center line.
Holley HP from AED supose to flow 910cfm wet, 88primary, 98 secondary, 5.5 PV
Crane roller rockers
Blue thunder dual plane intake matched to blue thunder yates style heads. std FE size manley valves (2.19x1.8 I think) 5 angle valve job match ported and polished by hand by my builder.

All of our pulls are SAE. This is a dynojet chassis dyno. The first pull was 369HP. I let a tear roll down my face. We were running lean at 3500rpm. Switched to a new holley 110gph mechanical pump and opened it up for 1/2 in. lines (From tank to carb). We finally got the A/F ratio acceptable then ran the timing up and down. The second pull was 396HP. We checked the timing and my initial was only 8degs with 21 in the dizzy for 29 total! So I am thinking thats the problem. We set the intial at 14deg, pulled again, same, same. We finally set timing at 34 total for max torque and 3 less HP to land at 407HP and 428TQ. I think that is really low for what I have. Street motors make more than that on pump gas! What could I have missed to find the rest of the horses?