So my Wife, our 3 little ones and I were given a Blazer for free. The engine was blown and the trans we are told is good. I pulled the engine out today and have a rebuilt 4.3 coming from AutoZone this Wednesday. I will be replacing everything. Water pump, Radiator, a/c system, thermostat, and oil cooler lines. It has the new style spider injector on it. Is there anything that I can do to add a little power to the engine or make it more bullet prof? Money is very tight. I think I will have maybe $300 extra to put in it.
Any and all input is welcome.

 

After the install, a crankshaft position sensor relearn must be done. Camshaft retard needs to be checked, and adjusted if necessary, as well. Both require a capable scan tool, (AZ can't do it). These two things will allow the PCM to make accurate adjustments, and provide the best possible performance, without spending a ton of money.

 

You can definitely feel the difference in power as an engine breaks in properly.

You need to prime the engine oiling system before start-up, rotating the engine 90° between maybe 1 minute priming segments - so get a small block Chevy priming tool from some place like Jegs. (You want it to start and oil immediately so don't crank it to build up the oil pressure). Break it in properly using true 10W30 or 5W30 break-in oil (not break in additives, not diesel oil - I used Comp Cams 10W30 in past because of price, but Joe Gibbs has 5W30 bereak in oil) for 1-2 hours or so, varying engine speed and not idling much (take it for a drive around town) - then change oil and filter to regular non-synthetic all-dino 5W30 of your choice for the first 1000 miles. Be sure to cut the oil filter open and look for metal particles after initial break in. For the first 1000 miles, romp on the throttle up to 4000RPM occasionally when going down the road (make it pull hard through the gears for a little while once in a while without over revving) to hasten the rings seating and keep the cylinder walls from glazing before the rings are fully seated. Then change oil and filter again with regular non-synthetic all-dino 5W30 through the 4000 mile mark. Expect the SES light to come on until you have the crank relearn done (this should happen during the 1-2 hour initial portion of the break in - know that engine will be taken above 4000rpm to do the relearn, so I wouldn't do it immediately). The CMP retard setting should also be set to zero (Make sure distributor gear is not worn and put a new Delco Cap/Rotor on it) to avoid crossfiring within the cap (troublesome with Blazer Vortec V6s). Doing this the engine should be fully broken in by 4000 miles if machine shop did the correct prep of the cylinders for the type of rings used. After that you can switch to semi-synthetic or full synthetic oil if you like, but always run 5W30 in your Blazer. I prefer to use non-synthetic and change oil/filter at 3000 miles. Use a premium oil filter such as a Wix in all cases (O'Reiley's).

If you want to invest in something that will give you something back, you could invest in HPTuners software or the like so you can do your own crank sensor relearn + monitor CMP Retard and diagnose a lot of other stuff later. HP Tuners VCM Scanner STD (for Windows) is $349 and comes with a proprietary bidirectional USB interface. Please be aware that no inexpensive software does both things, but Car Gauge Pro will monitor CMP Retard for $8.95 if you have an Android and a $25 BAFX Bluetooth adapter. Otherwise take it to the dealer or shop with high class scanner and pay $$$$

I'm sure others can come up with comparable software that will do crank relearn, CMP retard, injector balance tests, and control of different solenoids in trans and TCC as well as many other things. HP Tuners is just what I have used. I believe Autoenginuity is another, as well as EFI Live. Not sure on their pricing.