I spent a year building a 7.4L vortec for my 97 K3500 dually. I worked on the heads for a couple months. I ported and cc matched the ports (flowed 295 cfm on intakes), chambers were cc matched and polished, and the manifold was matched and ported. I put in a comp cams 08-411 cam (212/218 at .050), built my own stainless headers, put in 36 lb/hr Bosch injectors from 5-0 racing, and swapped to a 0411 ecm. I bought the ecm on ebay and had it loaded with the L31 350 van tune for a starting point. I made several posts on this board in the last few years with questions about buying an HP setup and tuning it myself. I decided it was too much to take on from ground zero, so I sent it to Black Bear performance for tuning.
My question has to do with efi wot timing. What is factory timing in the 98-06 gen 3 era? By normal wedge-head engine building, you use 34-36 degrees wot advance, all in by 3500-4000 rpm. And that's with a carb and conventional distributor. The vortec direct port injection will have perfect fuel distribution compared to a carb, plus less spark wander than a conventional distributor. There should be far less tendency for any one cylinder to approach detonation before the others.
When the 0411 first came back from Black Bear, there was only 22 deg at wot. Cruise timing was way low too, mid 20's rather than mid 30's. I sent it back with the data logs and asked for more timing. They did add cruise timing, but wot is still 22.0. For the record there is no trace of knock. I wrote back and asked why they didn't add wot timing, and they say 22 is what it should be. Am I wrong here? Do efi engines need that much less? Won't the knock sensors immediately pull timing if there is knock?
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Originally Posted by Scott-m
