Was very interesting, turns out we were having some detonation problems on higher loads at low-mid revs. We put the timing back from 34° all in to about 25° all in which reduced it but didn't cure it entirely. Either the air/fuel mixture is incredibly lean or the TDC mark on the harmonic balancer is in the wrong place. We looked at the mixture first and changed the standard rods (0.113 main jet and 071x047 rod) to stage 1 rich +4% - calibration point 10 for edelbrock #1407 carb (0.116 main jet and 073x047 rod).
This helped a lot but still didn't entirely eliminate the problem but sadly we ran out of time. We learned an awful lot though. The road was set up to hold 80mph which is about 3800 in 4th and we then observed what was happening throughout the full throttle range. In the end we had it running nicely up to about 2/3 throttle as the secondaries start to come on then it detonates. Not perfect but a lot better than it was. I thought I had a rattle in the exhaust where I put some screws in to hold the collector on but it turns out it was pinking! Whoops!
Next jobs are to check the timing mark is actually at TDC as it was a bit odd we had to back the timing off so much. Then after that we'll change the standard orange rod spring for the stiffer pink spring from the carb calibration kit to keep the rod up and get more fuel in (assuming its a lean problem).
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