This is a donor 350 engine out of a 1990 4X4 suburban
The engine is now at rest in a 1997 CK1500 4x4(it had a 305 I believe)
The engine ran strong and without any knocks before it got transfered.

The engine mapping in the controller must be compatible with the engine cams and characterestics of the transmission. I think you may have a 1997 controller on a 1990 engine and the two may not mix. It has to be checked out. And you need to get the temperature gage working. Are you sure the electric fan control is working?

Unfortunatley, this may not be the source of your knock.

Since you have swapped in an older engine into a newer model, you probably will have to convert the 1990 engine to 1997 (sensor and control wise) to become compatible to the engine controller and wiring harness.

#1CRANKSHAFT VARIATION RELEARN (CASE Learn)

"CASE" means: crankshaft angle sensor error. A crankshaft variation relearn must be performed if:

A diagnostic trouble code of P1336 is present.
The computer has been replaced or re-programmed.
The crankshaft position sensor has been replaced.
The engine, harmonic balancer, clutch, or flywheel have been: disassembled, removed, or replaced.
The crankshaft position variation learning feature enables the computer to compensate for part manufacturing tolerances. This allows the computer to accurately detect an engine misfire throughout the engine RPM range. The learning process is stored in the computer’s memory and does not have to be repeated unless one or more of the above conditions are present.

To perform the relearn, proceed as follows:

Connect a scan tool to make sure there are no trouble codes stored in the computer’s memory. If there is any power train trouble code other than P1336 (Crankshaft Position Variation not learned), the computer will disable the relearn function until the problem that aused the code has been eliminated. Also, make sure that the engine coolant (check it when the engine is cold) and oil levels are at an acceptable level.

1. Set the parking brake and block the drive wheels. Make sure that the hood is closed.
2. Start the engine and make sure that the engine coolant temperature is at least 158 degrees F. (70 degrees C.)
3. Turn the engine off for at least 10 seconds.
4. Select the crankshaft position variation learn procedure (CASE Learn)on your scan tool.
5. Make sure that the transmission is in Park. Start the engine.
6. Apply the brakes and hold the pedal firmly.
7. Follow the scan tool instructions.

Remember: That you are going to increase the engine speed to approximately 3000 RPM, 4000 RPM, or 5150 RPM. That’s the variation learn fuel cutoff RPM (depending upon the engine), and that it’s important to release the throttle when the engine RPM starts to decrease as a result of the fuel cutoff going into effect. Failure to do such will result in over revving of the engine, causing possible engine damage.

8. Once the engine has returned to idle, check the status of Diagnostic trouble code P1336. If the scan tool indicates that the CASE has been learned, the relearn procedure is now complete. If CASE has not been learned, check for the presence of other power train codes. If any exist, correct the problem, then repeat this procedure.

***************************************************************
***************************************************************

#2 1997 Chevrolet C Pickup 5.0L, 5.7L, and 7.4L Timing

Below is the text from GM Service manual for 1997 Chevrolet C Pickup 5.0L, 5.7L, and 7.4L
Accordind to this you don't set the timing but the timing offset.
You need a "Scan Tool" that plugs into the truck and can read the data from the trucks computer.
Besides from that, it looks like a normal timing procedure.
You might be able to borrow a scan tool from a parts store, or at least use their tool and do it in their parking lot.

Setting Timing
Camshaft Retard Offset Test
The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:

With the ignition OFF, install a scan tool to the DLC.
Start the engine and bring to normal operating temperature.

Important
Cam Retard Offset reading will not be accurate below 1000 RPM

Increase engine speed to 1000 RPM.
Monitor the Cam Retard Offset.
If the Cam Retard indicates a value of 0° ± 2°, the distributor is properly adjusted.
If the Cam Retard does not indicate 0° ± 2°, the distributor must be adjusted.
Adjusting Camshaft Retard Offset

With the engine OFF, slightly loosen the distributor hold down bolt.
Important: Cam Retard Offset reading will not be accurate below 1000 RPM

Start the engine and raise engine speed to 1000 RPM.
Using a scan tool monitor Cam Retard Offset.
Rotate the distributor as follows:
To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
To compensate for a positive reading, rotate the distributor in the clockwise direction.
Repeat step 4 until 0° ±2° is obtained.
Turn the ignition OFF.
Tighten the distributor hold-down bolt to 3N·m(25 lb. ft.).
Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.

HTH
Bob

Beyond that, the "transplant" was something I would not advise someone attempt to do anymore. Sure some people get away with doing this and don't encounter significant problems. But when it comes to emissions testing (which also pulls the VIN to make sure that it matches) software issues arise because of the potential variation in displacement which causes problems with both the base fuel schedule, as well as the timing map. FYI the software is VIN dependent, so if you had a 305 and you replaced it with a 350, the initial base fuel calculation will be short, which fuel trim will need to correct.

There are so many potential traps, and you cannot go to a book for help once you start down this path.

You appear to be sure this is a rod bearing knock. Why then did you write this?

Quote "It sounds like a rod bearing. It gets loud like one. But,it don't knock at idle and when I tack the RPMs up quick it doesn't knock. It knocks only when I ease the gas on and starts a bit after it." Quote

You did everything that you could to convince a reader that the sound is almost anything except for a connecting rod noise.

Are you in fact attempting to describe carbon on top of one or more pistons causing a knock? The carbon if built high enough actually contacts the head and it will hammer like crazy at times.

Changing the cap and rotor would be a waste of effort IMO. You could cancel cylinders to see if you can identify the source of the sound to single cylinder. This comes in handy for diagnosis of wrist pin, or piston skirt issues.

As far as just throwing a set of bearings in it, if a bearing spun, then the rod should be resized, the crankshaft should be polished, the clearance of the bearing measured in case an oversize is required, and you cannot complete this correctly in chassis.

If it is a hard knocking type sound, and if it didn't do it before this transfer, a carbon knock like john g suggested would be a pretty good guess imo and easy to fix. Get a can of carbon blaster, top engine cleaner, whatever you want to call it, and follow the instructions. I've used the stuff several times over the years for carbon knock and it worked every time. Carbon knock sounds a lot like a very bad rod or wrist pin to me.