How To Run In A New Engine

By Bill Ballinger

The following procedures assume that proper assembly and installation
procedures have been followed for rebuilding and installing an engine.
Proper fuel and ignition management must be ensured, as things will be
happening very quickly upon initial fire-up. If you are in doubt about
how these procedures have been executed, seek competent advice before

Pre-oil the installed engine before installing the distributor by filling
the crankcase and filter and spinning the oil pump shaft with the proper
socket and drill. Install the distributor and time statically according
to procedures in your rebuilding manual.

To assure proper cooling system bleed, leave the top heater hose off
of the water pump when filling. Fill the radiator until coolant spills
from the pump fitting. Install the hose and finish filling. Let it sit
for about 4 hours, ( I like to let it sit overnight ) then top it off.

Pull the coil wire and crank the engine over until oil pressure is
indicated at the gauge, or the indicator light goes out while cranking.
Hook up a timing light and make sure that the distributor is loose enough
to move. Fire the engine and quickly check the timing , speed is important
as the cam must be run-in . Don’t let the engine idle any longer than
is absolutely necessary.

Follow the run-in procedure recommended by the cam manufacturer for a
new cam. Usually they recommend 2500 rpms for 10 minutes, but I like to
very gently rev it up and down from 2300 to 2700 rpms after about 5 minutes
to set the rings.

Watch the oil pressure and temp. As soon as the thermostat opens,
( the top radiator hose will get warm and you’ll feel the water flow when
you squeeze it ) carefully pull the radiator cap off and top off the
coolant. Don’t let the engine overheat.

As soon as you know that it’s leak free and holding oil pressure, and
there is no danger of overheating, set the timing and tighten down the
distributor. Take it up the road a few miles, moderately accelerating
( the purpose is to get it under load ) and gently bring it down.
Deceleration is bad at this stage. Avoid keeping it at any one speed for
ny distance.

Park the vehicle on concrete or cardboard to detect any leaks. Do not
run the engine again until it completely cools, usually overnight is best,
Before restarting the engine, check the oil and water again and top off
as necessary.

Comments ()