I just build a 406..Trying to get it tuned ... its idealing pretty good but under a load it feels very under powered and rough.. Ive been messing with the timing but im think I might have to get it towed out and dyno tuned.. mods in sig if anyone has any ideas???

 

just checked and im putting out about 42lbs of fuel pressure and about 12*BTDC..this is on a 406 with brodix 200IK heads and a comp XE 284 cam

 

Run a compression test. My motor went down on power after breaking the motor in for the first 500 miles, then lost alot of power. After doing a compression test, I notice 2 cylinders like 20 psi or more low. Did a leakdown test and heard the pressure release into the crankcase. Bad rings on those 2 cylinders. Taking motor back out to the shop and have them install new rings. Could be from fuel wash or just defective from the factory. Also make sure the cam is installed correctly straight up and down or advanced/retarded as per your cam manufacturers instructions.