breaking in a rebuilt 350

[65cutty]

hows it really done? I know the cam has to have 2000 rpms for about 20 mins, but after that? thanks ....jim

[Texascarnut]

Originally Posted by 65cutty

hows it really done? I know the cam has to have 2000 rpms for about 20 mins, but after that? thanks ....jim

I always figured that after the first 20 minutes at 2000 rpm idle you jump in, head for a long stretch of open road and hammer the heck out of it until the rings set. If it blows up, it had to be a bad rebuild!

[citcapp]

Always drive 500 miles or so at different speeds, change the oil and away we go.

[joe_padavano]

Originally Posted by citcapp

Always drive 500 miles or so at different speeds, change the oil and away we go.

X2. Here's the process I've always used when building a new motor:

1) Liberally coat the cam lobes with assembly lube.
2) Soak new lifters in a coffee can full of oil prior to installation
3) Pack new oil pump with vaseline prior to installation
4) Prime assembled motor just prior to installing distributor
5) Get static timing close. Leave distributor slightly loose. Connect timing light.
6) Fill carb float bowl through vent tube
7) Have helper crank motor while you check timing and rotate distributor as necessary
8) When engine fires, quickly check for leaks and tighten distributor bolt
9) Raise RPMs to 2000-2500 for 20 minutes to break in cam
10) Shut down, check for leaks, retighten header bolts (you can never do this too often)
11) Drive for 500 miles under varying conditions (accelerate and decelerate) to load both sides of the rings.
12) Change oil
13) Drive the wheels off of it.

I should add that you should ALWAYS have a fire extinguisher handy when starting a new motor for the first time. While I have never had a fire, I did have one exciting moment when the head gasket on a brand new motor blew shortly after the initial start, sending a spray of coolant out. That was the first and last time that I ever used a no-name brand of head gasket!

Replaced the gaskets with FelPro and the engine was fine.

[AJCDFIN]

I agree with Joe adding avoid excessive idle for a couple thousand miles. Happy Motoring !