Originally posted as a reply to an issue, but at the request of some board members who saw it, I have edited it and reposted it here.
Engine break in prep and procedures.
Because this comes up from time to time, here are a few pointers, and a video.
Successful new engine break in, starts when assembling the engine.
I use a heavy assembly lube, such as Clevite's "bearing guard" on all engine bearings during assembly, including the cam bearings.
Lifters are installed with just a little oil on the sides, but with the cam break in lube on the bottom. Soaking the lifters in oil, makes it impossible for the cam break in lube to adhere to the bottom of the lifters. Do not soak or "pump up" the lifters manually.
The valvetrain was setup and preloaded/lashed properly.
The oil system was primed
The distributor was installed and timed close enough to start.
The carb was checked for jetting, and set close enough for initial startup.
Then, at the dyno shop, the timing was checked by just turning the engine over briefly, with the ignition system on but no fuel in the carb, so it won't start, until we are ready. But it is verified the timing is close, and the distributor is in correctly.
Then, the carb is filled with fuel, via the electric fuel pumps, the float level is checked, and needle/seat sealing confirmed.
At that point, we go to the vid..
Now, what's happening here is simple
Immediately the engine is brought up to 2000 rpm
timing is checked and set at 30*, which is where I set all NA engines to start with at break in.
After a quick glance up at the A/F ratio meter in the cell, I see it's running lean, so I do a quick check for vacuum leaks.
No vacuum leak is seen, so the carb is adjusted richer, via the 4 idle mixture screws, and brought to right around 12.5 to 13-1 A/F ratio. Not too rich, and not too lean.
Temps are checked with an non-contact thermometer at the back of each cylinder head, to insure water flow and even warm up.
A small leak on one of the external water lines (this is a filled block engine) is noted, Ron hands me a wrench to tighten a hose end a touch.
At about 3 1/2 minutes in, Ron notices the header primary pipes are glowing, he asks me what compression the motor is.. this one is only 8-1, as it's actually set up for a Supercharger, and because of the low compression, we compensate for inefficient fuel burn in the cylinders, with another 4-6 degrees of timing. The engine responds to the extra timing, and the headers stop glowing.
Low compression engines, can glow the pipes, from the excess fuel burning off in the exhaust and headers. It's worst with a STG 2, due to the very short exhaust port.
This is not something I have ever seen in a 10-1 or higher engine. But be aware, headers glowing is never a "normal situation". In a low compression engine like this, you might have to bump the timing to burn the fuel completely, but this is done only after your sure that your A/F ratio is correct.
Typically, glowing headers indicates an engine is lean.
A word on Q-jets: Typically these carbs are lean and break-in rpm. The carb was not really designed to run at this speed, with the choke open, and no load on the engine- To allow for break in, it is recommend that you close the choke plate slightly, to richen the mixture. Pretty simple here-- just close the plate until the engine speeds up.. if you go too far, it will start running poorly. Then you can use a small chunk of duct tape, between the choke plate and the back of the air horn wall, to hold the plate in position.
In our video here, notice thatat no time is the engine ever allowed to idle. The higher oil pressure at above idle rpm, and the splash lubrication provided by oil coming off the connecting rods, is all that lubricates the cam, during the critical break in phase. All adjustments and tweaks are made with the engine at that rpm, and two sets of eyes are on it, looking it over.
If you encounter a problem that can't be fixed easily, then quickly bring the motor back to idle, and shut it down. Once the problem is repaired, then start it back up, and get it back to break in rpm immediately.
This was just the first 4 minutes, but the rest of the vid is pretty boring, as it's just another 15 minutes or so of watching it run. Everything need for a good break in, was done either back at the shop, before it was started, and then right after start up.
That first 5 minutes is the most critical time in an engine's life.