I'm just about ready to start up a rebuilt engine. I have the distributor in and the timing mark show TDC. The documentation on breaking and engine in say:

Start the engine and bring rpm up to 1200-1300 rpm until water temperature just begins to rise. ... Watch your timing mark to make sure you are between 15-25 degrees. As soon as your water temperature just starts to rise, bring rpm up to 1800 rpm, and check ignition timing to make sure you are approx. 22-25 degrees timing for engine break-in. Run the engine at 1800 rpm for at least half an hour, making sure someone is monitoring oil pressure and water temperature at all times! After your half hour or more break-in, bring engine up to 3000 rpm and check total timing. Most engines need to be between 32-38 degrees total timing. Bring engine to idle and quickly check initial timing. Time to factory specs.

Is there anyway I can measure the voltage (or resistance) to the no. 1 spark plug to set the timing when the engine is off?

 

What I've always done is bring number 1 piston to TDC and set timing pointer to 15 to 20 degrees. A little advanced is fine for break in. Will start faster and with no load fine to run. With a flat tappet cam I wouldn't mess around at 1200 rpm waiting for temp to come up. Bring it up to 1800 to 2000. Vary rpm a little. Monitor temp and leaks. Run it twenty minutes. Shut it off. Pat on the back. Reset timing to spec before driving. Zinc oil or additive. Good luck.

 

If you want to set rough timing, pull the #1 plug, put your finger over the hole, bump the engine over until you feel the compression, get the marks on the balancer lined up with the pointer, 15 degrees or whatever you want, put the plug in the spark plug wire and ground the plug, turn the ignition on, loosen the distributor and rotate it the opposite direction that the rotor spins until the plug sparks, do it a few times to get the feel of where it is, you want to stop rotating the dist the second it sparks, lock the distributor down, you will be within a few degrees of being timed.
Loosescrews is right, no less than 2000 rpm, add zinc additive if you don't have a zinc oil already, minimum 30 minutes running for flat tappet cam break in.

 

And as you may already have read, if you run into any needed adjustments to the carburetor, or timing, or fix a leak, or whatever, just shut it down while you do the work (other than setting timing that is) so you never idle it.
I totally agree that 1200 rpm is risky at best. Even if it's only for a few minutes, it's literally the most important first few minutes of your engine's life!

The cam relies almost 100% on "splash" oiling for the lobes. You get splash from the spinning components, and some bleed-off out of the edges of the cam bearings, then drain-back from the lifter gallery. That's it.
Only the cam bearings actually get oiled like you would expect, with pressurized oil. So speed is of the essence. In more ways than one.
I don't know how long the assembly lube will last on a lobe after startup, but I'm guessing it's only moments at the most. So you can't rely on that for very long.

I will often shut down after 15 minutes too, to give it an extra heating/cooling cycle in there. It's not necessary, but quite often a brand new engine will run a bit hotter than normal and some people don't like that. I don't happen to think 10 or even 20 degrees over normal is anything to worry about, but I don't mind letting it cool down a bit either. Both are normal cycles in an engine.
Just no idling!

I'm guessing that the person that came up with the lower rpm initially suggestion was thinking about the different components coming up to their working temperatures so they would play nicer together.
Seems reasonable on the surface, and it's something we try to practice in the daily life of any engine. But when it comes down to it, it's only the cam you're worried about at the initial startup. So I'm with the others and say bring it up right away.

I use 1800 to 2200 as my minimum range, and 2200 to 2500 as my preferred range (my first engines back in the '70's were always at 2500) and 20 minutes as the absolute minimum, with 30 minutes preferred. And so far I have never had a problem.
Can't believe I just jinxed myself! Where's the wood to knock on!

As you can see by the normal procedures though, having your exhaust connected beforehand is a really good thing.
And the neighbors (if you have any?) will be very appreciative!

Paul

 

I don't fill radiator with coolant either. Open the petcock with a running hose in the radiator before starting. Gradually keep opening and turning hose down until you have an even flow in and out. Leave it like that when running it in. Keeps cold water going through everything for break in. Definitely want someone monitoring it all though. Glad my wife is patient and helpful.

 

I put a mark with a sharpy where the #1 is on the distributor body, makes it easier and more accurate to line up the rotor. A little judicious adjusting and you can dial a bit of advance in. Engine always fires right off and base timing is withing a few degrees. All this assuming you know how to get the engine on TDC compression and are able to juggle the dist. onto the oil pump shaft. I tape a deep 1/4 inch drive socket to an extension (so it doesn't fall off in the engine) and just keep turning the oil pump shaft a little until the distributor falls on it. A properly installed distributor should have the vacuum advance pointing pretty much straight forward.

I usually start dumping in the coolant early, while still buttoning up other stuff, refil occasionally. If you give it an hour or so, most of the air will have risen to the top. There isn't much arguement on how to run in a new cam. After the cam is run in, I take the vehicle out on the road. Use second or third gear, one gear lower than direct, accelerate full throttle to 4000 rpms or so (don't over rev a new rebuild). Then back off the throttle all the way until back down to 1500 or so. Do this 10 times and the rings are seated and the engine is ready to have the break in oil changed out and be driven normally.
Als, it's bad luck to put the hood on until everything checks out.

 

great Idea with the hood,Im approaching all this as well ,thanks for valuable information