Someone School Me On Timing! ??'s about Break In

[Isaiah Estrada]

Hi all, you may have seen the exciting post where I finally got the '68 fired up! I shut her down real quick though before proceeding with a break in. For one, I could hear she had a miss somewhere and was running pretty rough. Spark plug wire came loose on #6, my firing order was correct. All good! Also, our makeshift exhaust got blown off the second this thing fired, uh oh - we were getting smoked out when it finally DID run for about a minute.

So no, I have not yet broken in the cam. I don't believe I've ruined it, for one - it is a stock spec replacement cam. No heavy springs or anything like that - and it ran for only a small amount of time. I am not too confident with my timing - I'd like to be confident with that knowledge before I proceed with the break in process and fire her up once more! (and fix that exhaust lol.)

TO START! I followed one of Uncle Tony's vids on setting up a new engine for a first start. Found and verified TDC on the compression stroke, 0 mark on the damper lined up with my timing tab. From there, I set the balancer at 10 BTDC and installed the distributor. I made sure the rotor was pointing at where number 1 is on the factory diagram.

So, would this now mean that those 10 degrees of advance is my "initial" timing? I know there is "initial" and "total" but I get lost in understanding the difference between the two. So, with a dial back timing light - what do I want to see once I fire up that 440 and bring her up to around 2,000 RPM?

Also, should I do the break in with the vacuum advance disconnected, or do I leave it on?

Another newbie mistake, I didn't tie the choke open while I had it running either. Will make sure to do that before I proceed with running it for 25-30 minutes. I'm at least hoping I didn't ruin the cam. It's my first engine and I'm still learning! Also scary, where the bellhousing meets the block - I noticed an oil leak on the floor. I'm hoping that it's just some loose oil pan bolts and not the rear main seal... This car makes nothing easy for me! I know the rear main seal is supposed to be clocked a certain way so that the two halves don't line up with where the caps meet so as not to create a leak, but I didn't do that job. I guess I'll wait and see what it is after I finish breaking in the engine...

 

[413]

The rear main can be even with the block, I do it that way every time, zero leaks. The factory did it that way and they didn’t leak either. It doesn’t need to be clocked any certain way, or gooped up with sealer.

look on top rear of the engine for the oil pressure sensor and make sure it’s not leaking oil there.

can you take the car outside to break in this cam?

You can use a timing light while it’s high RPM for the Breakin.

2000 is the lowest RPM you want for cam break in. Varied RPM 2-3K is good also.

You can change the timing while the process is going. Retarded timing can get the engine hot.

Have a box fan handy to blow air at the radiator or engine if it’s warm weather there.

 

[Outsider]

Hopefully you have the lip on the main seal facing the right way. And as 413 said, check the two top rear located oil sender ports for leaks.

Yes, get the choke open as soon as it will stay running, you don't want to gas wash the ring seal.

For timing, I block the vac adv, just to keep things simple. And it's better to have too much timing than too little for a break-in, 15-20 deg initial is good, and if the total is 40 or 45 for break-in you'll be good as long as you set to a more reasonable 32 deg total before you drive it and put a load on it.

Most important thing during break-in is to get it up above 2k rpm, vary the rpm periodically (I don't worry about blipping it to 4k after it's warmed up) and make sure you don't let it idle for the first half hour or so.

 

[Jakter]

I'd be concerned you wiped off the assembly lube on the cam while running it a short period.

 

[furious70]

You'd been better off to just keep running it, leak and all unless it's a gusher.
You had done enough with timing to be close, and as others said just check it while it's breaking in.

 

[Isaiah Estrada]

The rear main can be even with the block, I do it that way every time, zero leaks. The factory did it that way and they didn’t leak either. It doesn’t need to be clocked any certain way, or gooped up with sealer.

look on top rear of the engine for the oil pressure sensor and make sure it’s not leaking oil there.

can you take the car outside to break in this cam?

You can use a timing light while it’s high RPM for the Breakin.

2000 is the lowest RPM you want for cam break in. Varied RPM 2-3K is good also.

You can change the timing while the process is going. Retarded timing can get the engine hot.

Have a box fan handy to blow air at the radiator or engine if it’s warm weather there.

Hopefully you have the lip on the main seal facing the right way. And as 413 said, check the two top rear located oil sender ports for leaks.

Yes, get the choke open as soon as it will stay running, you don't want to gas wash the ring seal.

For timing, I block the vac adv, just to keep things simple. And it's better to have too much timing than too little for a break-in, 15-20 deg initial is good, and if the total is 40 or 45 for break-in you'll be good as long as you set to a more reasonable 32 deg total before you drive it and put a load on it.

Most important thing during break-in is to get it up above 2k rpm, vary the rpm periodically (I don't worry about blipping it to 4k after it's warmed up) and make sure you don't let it idle for the first half hour or so.

Thanks fellas!!!! Real helpful info here. I got a proper exhaust rigged up now. Will be restarting it very soon.

 

[413]

Remove the power steering belt, just to avoid any problems there while braking in Cam.

 

[66furys]

I am very old, as well as old school, and I have never heard of this kind of discussion, ever. First, assy lube is ONLY there for some initial protection until engine oil gets moving.....which is why some prelube with an oil pump driver with dist removed. But, once the oil is alive, all is well. Much more important, imo, is the type of oil you put in for the initial break in, and then of course, the type of oil you use regularly in an engine with flat tappets.....that is, unless you have a roller cam here.....I dont know. ALL of our gas engine oils had the zinc and phos removed about 20 years back to save the planet and the catastrophic converters. So, for ALL flat tappet engines, I add some ZDDP, which is a wear inhibitor, specifically for the types of high pressure apps like cams and lifters.....not bearings or pistons. Imo, timing has not a thing to do with any of this. Yes, too much raw fuel can wash a cylinder, but this will quickly correct itself with running engines that have correct cylinder spash or spray from the rods, and of course, good lube. And the last thing is the break in oil that has no detergents, which do just that, wash the cylinder walls. One last last point is about the forces generated on the lifters, by the valves. I have not seen the cylinder pressure study for lower RPM loads, but surmise that as RPM rises, even with no outside loads, so does cylinder pressure and temps. So, how does that translate to the force necessary to lift a valve, esp one with lots of overlap, as the cylinder pressure is dropping and that exhaust valve is opened....hmmm. Light loads and speeds for a while, with lots of changes to have the intake vacuum pull oil up the cylinder, which is what happens going down the road with worn rings, and smoking when you let off the gas.

 

[rd92west]

I'd be concerned you wiped off the assembly lube on the cam while running it a short period.

The zinc in the break in oil will be sufficient to keep things slippery.

One question I would ask is - did the rod bearings get notches filed for the squirt holes? I see lots of guys claim they are unnecessary and bearing manufactures dont worry about the notch. In my uneducated opinion i feel the notch cant possibly be a bad thing. Especially at break in, the more oil flying around the better.

 

[413]

I like the notch so I asked. I work with a great machinist who is early 70‘s now, he says the notches are not necessary and there is plenty of oil coming out of the rod bearings to lube the cam. The no notch bearings have been out for a long time and no adverse effects.

so I‘m not concerned and have no problems Without them.

 

[66furys]

Some rods have a hole, a squirter hole to add oil to the cylinder bores. And, in some extreme builds, there are actual pressure nozzles that spray the cylinder lower bore and the bottom of the piston for cooling. But, the cam is lubricated by the oil gallery that runs between the cam and main bearings in the block. However, this also pressurizes the bore of the lifters, that then allows oil pressure up the bore of the lifter push rods. This lifts lube to the rockers and valves, as it is. Not all engines have these small holes in the rods to spray the cylinders. Most just rely on splash. Like some lawn mower engines that have no pressurized oiling, and rely solely on splash for everything....not too good, but works, as it did in the early days of engines. And of most interest in US engines, is that the OP is provided to the main bearing via a hole from that main gallery. Then, this OP has to travel from said main bearing, thru a crank drill to the rod bearing that has this spray hole. So, often, by the time the oil gets there, there is no more pressure left for anything. The russians use a hollow crank, that has OP to deliver to all bearings, not just mains.....interesting.