First start, break in procedure questions...

[GXPWeasel]

Okay, so I've read through multiple post on here regarding break in procedures for a new engine / cam, and threads regarding setting the timing, and making sure that you're getting oil pressure to the engine first, then start for the first time, so you don't dry fire it.
Here's where I'm confused though, or maybe stumped is a better word.

This isn't my first engine rebuild, but it is the first with a complete tear down, machine shop inspected, and assembled with non-factory parts with the correct tools. I rebuild a 350 from my '72 Skylark when I was in high school. Even converted that from a 2 bbl to a 4bbl. That engine was just a remove original parts, and put the originals back in, with new gaskets. Then I also built a 5.0 for my '92 Silverado, but it was basically stock replacement parts, as I was transplanting from a 4.3 to a 5.0. Didn't have great success with that one, but that's another topic. The point here is that I've done this before, but not when I've cared so much about the details, and had the correct tools.

Now that I do have the correct tools, and care about the longevity of my 305 that is being rebuilt for Daisy, I need to know how to proceed. See below.

I have read that once you get the engine started, you want to get the engine up to 2500-3000 rpm as soon as you can, and run it there for 20-30 minutes to ensure you break in the cam. Then you also want to drive the truck for 100 miles or so, varying the engine load / speed. Okay, I get that, and don't have a problem with that procedure. HOWEVER, how am I supposed to do that if I'm also starting from zero, pun intended, with my timing? If I'm starting fresh, with my cam dialed in at 0* per instructions, I will have no advance timing at all. What do I do first? do I dial in the timing, finding my preferred timing BTDC, then do the cam break in procedure? Oh, and to add to this, I've got a rebuild carb that I'm trying to dial in as well. I have no clue what the fuel trims / idle settings are going to be right off the bat. What if it takes a few starts to get the engine just to idle???

Help me out here guys... What say you on suggestions as to what should be my first concern? I'm not far away from doing this right now. I can choose to set the engine, then finish building the front clip around it before I fire this thig up (probably the route I'm going) or I can just set this thing in, and get it dialed in first, then finish assembly on the suspension / front clip.

I need advice.

 

[PrairieDrifter]

I would suggest going with a known decent working carb so you don't have to deal with that problem, otherwise you can do a non running base adjustment to the air fuel mixture screws to get you close for a break in, I believe it's three turns out from bottomed out on each one.

Yes 2500-3000 rpm for about 20 minutes. The timing you're talking about is the timing between the crank related to the cam, so if you were doing a specific style build you could either retard or advance the cam a couple degrees through this "base" timing I guess maybe just cam timing idk, the process of connecting the crank to the cam. You do this basically so you don't have to max out your distributor. So you can extra get timing one way or the other.

Your base timing will be set by where your distributor is positioned, in relation to the intake/swing of the dizzy. Set the dizzy in by rotating engine to top dead center of the #1 cylinder on the compression stroke, then drop the dizzy in so it's pointing directly towards the #1 cylinder.

If you degree your cam to zero in relation to the crank, you "technically" start at zero. But as soon as the dizzy is dropped in and the engine starts you basically "already have timing" it's all about the correlation between distributor, cam, and crankshaft.

Set your carb, Get it running, set your timing as fast as possible, leave the dizzy bolt/nut snug enough to hold it steady but not impossible to turn(doesn't need to be perfect at this point just get it close), if the carb needs minor adjustments do them quick, get it up in rpms and break in the cam, then come back and do some more light tuning on timing and carb then go do your driving and oil changes. Once she's broke in take all the time you want to fine tune it perfectly.

 

[Matt69olds]

You can set the timing by ear during break-in. As soon as the engine starts, run it up to 2000-2500, and slowly turn the distributor until the engine stops speeding up, then back it off slightly. Since the engine isn’t under a load, you don’t need to worry about detonation from too much advance.

Another option: Remove the number one plug. Rotate the engine in the normal direction until you feel compression from the number one spark plug hole. Keep turning slowly, stop when the timing marks read 12-14 btdc. Put a spark tester on the number one wire, turn on the key, but don’t crank the engine. If you rotate the distributor back and forth, you should see a spark from the spark tester every time. Assuming the engine is on number 1 compression, the distributor is timed correctly. Turn off the key, remove the distributor cap and rotor. Rotate the distributor until the pickup coil and distributor shaft teeth line up (HEI distributor) or the ignition point just begin to open. Tighten the distributor, reassemble everything.

Assuming the distributor has around 20 degrees of advance built in, combined with 12-14 of initial timing, that should be pretty close to the textbook 34-36 total timing.


Lastly, start the engine with plain water in the radiator. Open the drain of the radiator, put a garden hose in the radiator filler neck. Turn on the hose enough to keep the radiator full with the drain open. That way your constantly filling the engine with cool water. I have yet to break in a engine without puking water out of the radiator, and it’s hard to keep some engines from overheating with the engine recognition for a half hour. No point in puking fresh antifreeze all over the floor.

 

[GXPWeasel]

Thanks for the replies fellas.
I like the tip of the garden hose too, vs filing with coolant just to waste it on the ground.

 

[Bextreme04]

I'm going to do the obligatory link to GMPP directive for new crate engine break-in.

https://paceperformance.com/p-3978-gm-crate-engine-start-up-procedure.html

As others have said, try to get the ignition as close as possible before start-up and the garden hose is a great trick to make sure you dont have to shut it down before the initial break-in is done on the cam.

 

[QBuff02]

Just to clarify- cam timing has nothing to do with ignition timing. if you are on correct tdc for #1 cylinder when you drop the distributor in you want the rotor pointing at the #1 cylinder. you might have to take a long flat blade screwdriver through the distributor hole on the intake and turn the oil pump driveshaft to get it to line up (index) with the distributor gear so the distributor will fully seat on the intake when you install it. it might take a try or two to get it right. then when you put the plug wires on, you start with the number one plug on the cap where you indexed the rotor. And leave the hold down bolt for the distributor just loose enough you can turn it with a little effort by hand for when you go to verify timing after it fires up. That will get you right in the ballpark of being timed close enough to fire the engine off. It was stated above that you don't have to have the timing perfect when firing up because detonation isn't an issue, but you will want to get the timing light on it and get it set once it's running. If it DOES take a few starts to get it fired up, it isn't totally critical, but you do not want to crank and crank and crank on it. prime the carb wit some fuel as that will help. And most carbs have baseline settings to start with. Double check everything and then double check it all again BEFORE you try to fire it up, and if there are any issues once it's running (leaks, noises, loose hardware, etc) shut it right off and don't let it idle. if and when you fix an issue, crank it up and bring it right back up to rpm to complete the break in procedure. I have a big 40" fan that I point right at the grill and an old blower from a furnace that I use to keep fresh air blowing into the radiator from the front and then up from underneath with the blower adjusted on blocks to be pointed up in the right direction . I've never had one get hot on me during break in by doing it this way. Basically what I've said, I only expanded on what a few others have stated above and added a few details to help get you going. It doesn't have to be stressful to break in an engine, you just want things right or as close as possible before you crank that starter over for the first time.