Adding another Vortec V8 to the fleet

[Fast355]

Update- This poor 305 sat in the Vette before getting dropped into a 1980 Camaro to sit then finally found its way into a 1999 Tahoe. Have the Tahoe up and running. It fought the whole way. Previous owner had wired in a replacement crank sensor pigtail and although he matched like colors, two of the wires were swapped in the connector. Once I found that and replaced the fried sensor got it running, adjusted the valves and broke in the cam. This little 305 would have been fun in that Astro. Runs good in the Tahoe. Working on tuning the Black box for it now. LOVES Timing and I had to up the MAF and VE tables 10-15% in places to keep it from being lean. Pulls about like a stock L31 350 in the low-midrange and pulls signifigantly better from 3,500-5,200. Stock poppets are running 80% DC at 5,000 rpm to hold a 12:1 afr on E10. Timing is 32° BTDC at 5,000. We kept the stock torque converter and the Tahoe has a 3.73 G80 rear-end with heavy aftermarket 17" wheels and 31.5 tires on it I managed to break them loose a little but for the most part it just takes off and goes

[Fast355]

I thought I would chime back in on this. I added some parameters and history tables to my HP Tuners datalogging software to help tune the 305. I was fighting a start and stall issue at random times as well as a stall shifting into gear. I first doubled the normal idle air volume that I see in Park/Neutral and programmed it into the startup airflow table, then upped the decay time to 6 seconds, cold started the engine, dropped it right into gear (no stall) and used to software to average the idle airflow against the coolant temp values in the In-Gear Idle Airflow vs Coolant table to program those values. With the engine fully warmed up, I put the shifter into Park and observed the MAF sensor drop about 1.5 gms/sec. I offset the Neutral Idle Airflow vs Coolant table down 1.5 gms/sec. I then set the Distributor CMR to the factory specified 0*. I unplugged the MAF sensor to run the engine on the VE tables. Then observed the sensor readings while my brother drove the truck in mixed driving conditions around town and on the highway for about an hour. With a good amount of data, I used the fuel trim history tables to calibrate the VE tables. I then plugged the MAF back in and tweaked the MAF tables. I had previously put a performance oriented timing advance table into the PCM and adjusted the speedo and shift tables with BlueCat trans tuning software. I cleaned up the command shift time table and gave it a good line pressure table from a previous L31 Suburban I had tuned. Nice quick shifts without being too neck snapping. Much better than the lag in the stock shifts. In about 2 hours I was able to clean the tune up to the point the Tahoe fires right up, idles well, does not stall, transitions to off-idle and wide open throttle without bogging and feels nearly as refined as if it had come stock. Not bad for a 268 cammed (110* LSA) 305 in my opinon. I need to pickup the correct 305 knock sensor and knock module for the truck. The 350 sensor in the 305 block is picking up ALOT of false knock. I was seeing 4-8* of knock retard from 50 KPA and 1,200 rpm and beyond. Almost as soon as the throttle was open it was reading knock. I put a factory 305 timing table back in the PCM and saw the same exact result, except the engine was very gutless. I ended up looking at the maximium knock retard table and as soon as the PCM turns the knock sensor on it is reads maximum retard. Not sure if its a bad sensor from the 125K 350 or just because it is the wrong sensor. Either way I turned the knock sensor off (because I really don't like them either) and put the performance oriented timing map in it. It immediately woke up even more without the 4-8* of constant retard. Cruising down the highway it has no problem holding lockup in overdrive at 2,000 rpm @ 70 mph even uphill. When it downshifts though it comes to life and easily accelerates. At wide open throttle I am having to feed it enough fuel at 5,000 rpm to make about 285 hp at a brake specific fuel consumption of 0.5 lb/hr/hp. When it accidentally rev'd to 5,200 rpm I was feeding nearly 300 HP worth of fuel to it. We did discover that we need to pull a valve covers back off and play with the valve lash adjustment one more time on the driver bank. We have a single lifter that taps on startup, cold or hot for about 15-60 seconds before going away.* Starts right up, idle sits at about 1,200 rpm for about 6 seconds and then starts to decay down to the Idle speed target. Warmed up it idles nicely at about 750 in Park and 625 in Drive.

[Fast355]

So I am going to say the little 305 broke in well and still runs great. Has a small oil leak at the rear main and the 4L60E is starting to slip a bit. Will address the rear main when the 4L60E comes out and an 80E goes into its place. A few months aggo the truck got parked when a few issues popped up. The steering box and pump started leaking at about the same time. The OE fuel spider started acting up too. A few days later a rear wheel came off the truck at 75 mph after a trip to Discount tire a few days earlier. All 5 lugs were sheared flat with the axle flange when it happened. Picked up a 3.73 G80 rear-end from a lower mileage K1500 Suburban and replaced the front rotors with ones for a light duty 2500 Express van. Added a set of 04 Titan 17" offroad wheels. Changed the pump and steering box. Finally I took 2 different spiders, resealed the injector o-rings after testing and cleaning the best 8 poppets and replaced the regulator. After cleaning they all had a nice spray pattern. Truck is running better than ever. After replacing the spider with the cleaned and resealed one the truck is running a bit rich and needs some retuning work but plan on going with an 0411 soon. Also one of the cats went out and the cats were both changed to 2.5" Thunderbolt high flows and a magnaflow muffler put in place of the stock one. Still running the stock tubing before the cats but 2.5" after and running the stock tailpipe. Needs a donut gasket replaced on the passenger side one day whenever we get around to it. Also found the correct knock module and changed it and the knock sensor. False knock is also now gone.

http://www.youtube.com/watch?v=mqs1Q1eabek