with a problem. Truck starts and runs fine in the first three gears. EGTs at 1100 and 26lbs of boost at WOT. But once locked up in overdrive it feels like an anchor is behind me some where it still runs good, no missing, no smoke. Rpms take forever to come up and can only get about 17lbs of boost. The difference between 3rd locked and overdrive locked is night and day. Looking for suggestions. Thanks for replies.

 

The fueling profile of the injection pump has a great influence on where your power band begins and ends. Part of that profile is the internal fuel lead in the pump, another is the maximum fueling set by the fuel plate, and the one that most guys find the greatest impact with is the static pump timing.

I would suspect your static timing needs to be set up to somewhere around 16 degrees (unless you have had the pump's internal fuel timing set up, then you will want to settle on around 13.5 or 14.5 degrees).

Be a bit cautious, because the revised timing will make a lot more low end torque, and you can potentially fry your transmission if you just go out and floor it.

Automatic transmission engined injection pumps are set up with smaller delivery valves and lower initial fueling lead than found with standard transmission versions. This keeps from frying the transmission from too much torque. From your signature, you appear to have taken a fuel plate from a 5 speed and installed it in the automatic pump. I really do not recommend that approach, as it does not really gain enough fueling at the top end to compensate for the original pump settings, so your power would be only around 185-190 horses with proper timing. You would be much better off with TST's #6 plate with the factory injection pump settings and delivery valves.

Another thing with the 12 valve engine is that the nut on the injection pump timing gear is not tight enough from the factory. So, if you have not had it retimed and the nut set at the revised torque, your timing is probably somewhere down around 9 degrees or so. That will whack your power pretty severely and result in the power band being closer to 2,500 RPM's, so you lose low end pulling ability and run out of snort when in overdrive.