Basic M-Block Tune-Up Procedure

Step 1.

Clean the engine.

Steam clean or thoroughly de-grease the engine. It’s a lot easier (and way more fun) to work on a clean engine.

Step 2.

Check the ignition system.

Start at the spark plugs, and work your way back to the distributor. If it’s been a while, you may as well replace all the wear-out parts (spark plugs, spark plug wires, distributor cap, and rotor).

Appearance of the spark plugs tells a story. If you don’t have one, get at least a Haynes or Chilton manual with the page of spark plug color illustrations. Read the manual about what different spark plug conditions mean and what you might need to do to troubleshoot the problem(s).

Step 3.

Overhaul the carburetor.

Remove it, clean it, and rebuild it. Even if you’ve never worked on a carburetor before, you can probably overhaul a Motorcraft 2150 2V carb — they are that easy.

All you need is an aptitude for reading the exploded view drawings that come with the rebuild kits, some patience for working with teeny-weeny parts, a clean workspace where you won’t lose any of those teeny-weeny parts, and a sense of adventure. Follow the choke and accelerator pump adjustment instructions in the carburetor rebuild kit.

If you’re not so adventuresome, maybe you’ll be motivated by the desire to save the $200 (or more) it will cost for a rebuilt carb at the parts store.

Note: I'm including a carburetor overhaul in this tune-up procedure because many problems are caused by dirty or maladjusted carburetors, and fixing everything else but leaving the carburetor untouched is not a recipe for success.

For detailed information on overhauling and tuning the Motorcraft 2150 carburetor, check out this page .

Step 4.

Change all the filters.

• Air filter element

• Breather element

• Fuel filter

Step 5.

Install a new PCV valve.

Just to be sure, especially if you haven't done it recently. A faulty PCV valve can cause horrible driveability problems.

Step 6.

Change the oil.

Old motor oil can adversely affect the engine's performance and efficiency.

Step 7.

Check all vacuum hose routing.

Make sure all vacuum hoses are connected properly. Check the condition of all hoses, connectors, and vacuum diaphragms. This is critical to eliminating vacuum leaks — a major, and surprisingly common, tuning problem.

If you don’t have an engine calibration label with a vacuum system diagram, the best option is to look for another vehicle similar to yours that has one and refer to it.

The ProjectBronco web site has a calibration label posted for a 1979 Bronco, 351M with automatic transmission, here .

Step 8.

Set the ignition base timing.

Set the base timing according to the specification on your engine calibration label. If you don’t have one, start with 4 degrees BTDC.

You can look up some general '77 to '82 M-block truck timing specs on this page .