Hello all,

Today I was able to re-attempt my cam break in. Thankfully my stuck starter relay didn't return, and the truck started relatively smoothly. I was able to finish the 30 minutes of running between 2000-2500 RPM per Comp Cam's instructions. I do have some observations I would like to share and a couple where I would appreciate input.

I needed to have partial throttle in order to start the engine. Choke was set, and so was the fast-idle cam for the first start attempt - but after turning over for a while (maybe 10 seconds) there was still no firing. So then I opened the throttle a bit more and it fired up. I had my meter connected to measure RPMs, and the throttle was set to about 3k RPMs during start. I immediately lowered it to 2k for the break in and it continued running without issue.

At the end of the cam break-in, I tried to slowly reduce RPMs to see how low I could get. Around 1200 is started sounding a bit 'rough' and at around 1000 is abruptly shut down. No real sputter, no backfire, just dead. My guess is probably timing and/or idle mixture. My idle mixture is crudely set at 1.5 turns out. Don't ask me where 1.5 comes from... but I had it in my head. Please correct me if I'm way off.

My base timing was set at 10 degrees BTDC by lining up the pully with both the timing cover marks and the little tooth thingy (scientific term) and then stabbing the distributor so that the rotor was aligned with the #1 cylinder. I figures it was close enough to start with. I don't have a timing light (yet). I do have a vacuum gage. However, I feel like I need to get my idle down before I can adjust timing, right??? Because otherwise the mechanical advance will throw me off for base timing. Vacuum is disconnected and plugged, by the way.

For that matter, all vacuum ports on the carb and carb spacer are plugged. Even the bowl vent which would normally go to the charcoal canister. EVERYTHING is plugged with new caps, no cracks.

Also, I made a very small adjustment to the choke to make sure the blade was vertical before trying to lower the RPMs. So the engine dying at low RPMs isn't a choke issue (and the engine was HOT).

I don't have anything to measure AFR.

Any suggestions on getting it to idle in the most efficient fashion? My guess is to make carb adjustments first, then timing (once I have a decent idle RPM), and then go back to the carb for fine tuning...??? Please help :-)

 

Second observation (wanted to separate these into their own posts); I have some oil 'seeping' out from around the valve cover. I need to recheck the torque of the bolts. But I don't remember using any sealer, only the cork gasket. When I drain my break-in oil, I was thinking about taking the valve cover off anyway to take a look at the rocker arms and push rods - maybe check the retaining nuts / valve lash, etc. Opinions? Should I use some sort of oil resistant sealant with the gasket when I put the valve cover back on?

What about the push-rod cover? I don't see any leaking, but should I remove it and take a look at the lifters before putting fresh oil in? Maybe this is a stupid idea - but this is my first ever engine rebuild and first ever cam break-in, so forgive my nervousness.

Thanks for the input!

 

Ok, last observation (actually 2)...

I heard a lot of small noises during the 30 minutes. It's probably just my imagination and everything is ok, but I don't have the experience to know. One thing in particular was a 'whistling' from the top of the carb. It's the original carb for the motor, but again with all vacuum ports plugged. Is this normal or a sign of something?

Last observation - my coolant is BLACK. I filled it with straight distilled water + some Royal Purple to help with corrosion. Reminder, my block and head were sitting for 3 years after the machine shop had their hands on them (and tanked them) before I added coolant. My guess is that the crud I see is just the Royal Purple doing it's job and removing all the surface rust / corrosion that built up inside over the past 3 years of sitting. My plan is to flush and refill with the same (since it is still on a test stand in North Carolina, inside the house garage, so little fear of freezing). With the next run I'll see if the coolant gets any clearer. It may take 2+ flushes to get all the stuff out. Thoughts?

What's the best method to flush? Heater core is not connected. There is a simple hose looping from the water pump outlet to the thermostat housing (where the heater core hoses would normally go.

I can provide pictures if they are helpful?

Thank you all again! And at least the cam is broken in !!!

 

Once the point is reached where the camshaft is broken in running the engine without any load on it or idling time should be avoided. Cylinder finishes and piston ring materials play a role in this, but the idea generally has long been to get the engine under load right away to ensure a good piston ring to cylinder wall seat. Moderate full throttle acceleration and deceleration out on the highway will accomplish this. Otherwise "cylinder glazing" can occur.

 

Ah, yes. I forgot about that. This puts me in a bit of a pickle...

 

The problem with glazed cylinders, it's an extremely hard, smooth glass like surface that builds up, totally filling in the cylinder cross hatch. Run the risk of the engine being a permanent "oil burner". The only way to remedy this once it occurs is to deglaze the cylinders all over again with a ball hone. It's kind of a one time opportunity to break the engine in right. Modern engines use different ring materials and surface finishes and (I guess) this isn't the problem it once was.

The pros have all that engine break-in stuff down to a science, they are pulling full throttle dyno runs up to 7,000 RPM or whatever almost immediately, just as soon as the camshaft is broken in. They don't "baby" a new or rebuilt engine or anything like that, that's for sure.

Don't stress, verify the ignition timing and idle mixture is in the ballpark and drive it. The piston rings and cylinder walls need to get seated to each other, they are going to have a very close working relationship for the next 100k miles, and the only way that happens is under actual compression, under load. But definitely want to avoid simply idling the engine and dinking around with the carburetor or stuff like that. Git 'er done!