So, some more updates.
I've been fighting tuning issues with the TBI system on the 440 for a few months now. Issues that prevent me from even getting to the standard TBI "first step" tuning stuff. After completely going over the fueling system and nailing down some electrical gremlins, the truck was starting to run better and better each time I wrenched on it. What I couldn't get rid of this time was a ping/lack of power under load. I had tried removing spark, but it was getting to the point where I was crippling the engine's performance to try and eliminate the pinging. I sat down with a racecar buddy of mine and we did some math and realized that even if my engine is making a conservative 300 HP at the crank, the TBI unit injectors are far undersized. 148lb/hr total from the two 74lb/hr injectors running at 13 PSI. This proved to be a problem, as most people agree that the most adjustment you can get out of a stock TBI regulator is about 15 PSI and that isn't quite enough. So we went on a hunt to find a higher PSI spring for the TBI regulator to get us closer to 200~210 lb/hr. After checking the local junkyards for a 94-95 BBC TBI truck or a 95+ TBI van and coming up dry, I found a guy on Amazon who sells TBI parts and has the springs in stock. Hamilton Fuel Injection also stocks different PSI springs. I ordered a 28 PSI '95 model year style spring for my early 90's 454 TBI. While that was shipping I also ordered an adapter for the TBI fuel fittings to get a fuel pressure gauge on the input line for easy tuning.
For anyone who finds this thread, I also have some advice about the rear fuel tank. The 93 blazer tank worked great, my #1 suggestion is to get the higher PSI fuel pump. I didn't, I got the TBI pump which maxes out at 15 PSI. Luckily it is really easy to swap in the CPI pump which supports 60~ PSI and it's not expensive. Save yourself the time, get the 60 PSI pump off the bat.
Anyway, fast forward to this week and the new higher pressure spring was in the TBI unit and now we are pulling a solid 32 PSI of fuel pressure
That was a little more than I anticipated, but so long as it is steady and your math is good for the new injector constant the 7427 PCM seems to be dealing with the extra fuel just fine.
Now I was fighting the same problem with different causes, I still had no power/bogging but it was because we had enough fuel and no spark from messing around with the lower PSI. So I said screw it, blanked out the spark tables, and started over. I disabled everything in the .bin file that would play around with the spark curve and got to work.
This is the spark graph for a stock 454 .BIN file:
It doesn't look very pretty, does it? My 440 did not like this timing table one bit, so I zeroed it all out and started off with a very basic "mechanical" style timing curve. I am very new to the RB mopar crowd, so I had to do some googling to figure out what your average 440 likes in terms of timing. The general consensus was 16* initial with 36* of total advance all in by around 3000 RPM. I would later learn that this didn't entirely apply to my build, but I am new at this. This is what Version 1 looked like, very simple right?
That doesn't look too bad, and the truck would sort of run with this. From here, I selected the whole table and would add/subtract to all of the values at once to represent advancing/retarding a distributor. I got to the point where the truck would fire up real nice and pulled steady 23 inhg of vacuum. 22* of initial timing seems to be where it is happiest. Once I got that, I started playing with when peak spark came into play. My engine's cam tops out at 4500 RPM and makes peak power off idle and to about 2000 RPM. I accelerated the timing curve so peak spark was achieved by 2500 RPM and increased total spark from 36* to 40* at peak. Now we are getting somewhere! The engine really liked this, and for the first time I could lay on it down the street and have it take off like I felt it should. There was some minimal hesitation, but overall it was a huge improvement over previous attempts. I sat back down at the computer and added some "vacuum advance" to the finalized "mechanical" timing curve, and then smoothed everything over with Tunerpro's smooth tool. I ended up with this:
You can see that at WOT the timing curve looks exactly like the mechanical curve V1, thats because a normal distributor vacuum advance is doing nothing at WOT and you are relying on the mechanical advance for all the oompf. The engine *really* likes this timing curve. There is still a very slight hesitation, but I think that can be solved with a little more advance across the entire table. There is no sign of the pinging I was suffering from earlier.
At this point, I think I have the timing pretty dialed in and I am getting ready to move into the VE tuning via datalogging and watching the BLM's. From my preliminary datalogs, most of my BLMs are in the 110-120 area so the engine is running slightly rich but that isn't terribly far off from the "Ideal" 128.
Now I need to really nail down two final issues for this project. First, my transmission TV cable is getting on my last nerve. I can never seem to get it adjusted properly/keep it adjusted. The truck sometimes starts off in second gear, sometimes does't want to manually downshift to first, sometimes does't want to go into third. I am willing to say that my frankentrans handiwork could be the culprit but playing with the TV cable typically results in good shifts...temporarily. Not sure what I'm going to do there, I am tempted to rip the TV cable out and install a manual valve body. I drive a 5 speed F350 every day, a "semi-auto" Wagoneer would be cake comparatively. Issue #2 is a bouncing volt gauge. The interior lights/volt gauge bounce wildly at anything under 1k RPM. I've checked the grounds on the voltage regulator and everything there seems fine. I have to do some more digging on the mopar forums, but if any electrical gurus here have any ideas I am all ears.