Fire it up

How to light that new engine

Jim D. Moore - February 10, 2014 01:00 PM


Put a fan in front of the radiator and keep a water hose handy to mist it a little if needed to cool things down. Keep a fire extinguisher near.


You only need a timing light, a screwdriver to adjust the carb and a distributor wrench to lock down the distributor.

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QUESTION: I’ve invested a lot of time and effort into rebuilding the engine in my car, and I’m unsure about the PROPER way to break-in all the moving parts.

ANSWER: There really isn’t anything you can do about the assembly quality at this point. We just need to make sure we give all the new parts a fighting chance to get acquainted with each other. It’s important that the engine fires quickly and you keep it running through the initial run-in/break-in process. We don’t want prolonged cranking or a bunch of shut downs to repair problems. Here are some things you can do to make the first-fire as stress-free as possible:

  • Throw the battery on a charger a few days ahead of time to get it ready.
  • Position plug wires as far from the headers/manifolds as possible. There’ll be incredible heat pouring off those pipes in the first few minutes of operation.
  • Ensure you can instantly shut it down with the key. Thinking you can jerk the coil wire to kill it is a good way of getting a spark to light that fuel leak you just found.
  • You can plug carb/manifold accessory vacuum ports for the initial start-up. If your distributor has vacuum advance, attach it to a full vacuum port, which will help it run cooler.
  • Fresh gas. Fuel sitting around all year goes stale.
  • Fill carburetor with gas.
  • Clean up any spilled oil. Smoke from greasy handprints is one thing, but pooled oil can start a fire.
  • If you have new ceramic coated headers, consider using something else for the initial start-up. The added heat during break-in can permanently dull them. If they’ve already been run, they should be OK.
  • Leave the thermostat out. Waiting until it hits 180° before you start to cool things is too late. Leave the radiator cap loosened to the first position initially.
  • Got electric fans? Turn them on to run constantly.
  • No need for antifreeze right now. Pure water cools slightly better, but more importantly, it doesn’t make a mess if there’s a leak.
  • Oil: often an emotional conversation, but here’s my take. You’re not racing right now. You need oil that flows instantly to every corner of the engine and provides good lubrication. This means something like a brand name 0W-20 or maybe 5W-30 “dinosaur oil” at the most. I would never leave this oil in there for more than the start-up and maybe the first run around the block. There’s a number of “Break In Oils” that certainly won’t hurt anything and may help in some specific instances (flat tappet cams). If your cam manufacturer/builder insists on a specific oil for warranty, use it!


For more tips and instructions, read the complete story in the February issue of Cars & Parts, on sale Feb. 25.