Just completed a 25 minute break in run of my freshly rebuilt FC engine set up on an engine stand. All checks out ok except a small leak behind the clutch that I will investigate and deal with. Next I need to do some timing and carb balancing work. Am I out of the woods in regards to idling now after a successful break in run? I would like to get it mostly dialed in before I install it. Had high oil pressure at first, and when it warmed up it ran 35-40 psi, all normal. No bad sounds from the engine, just some mis firing I attribute to the need for dwell and timing adjustment. After 25 minutes of running with no issues can I consider the cam and lifters broken in?

Craig T
Central NY
1961 Tramp (truck with a ramp)

Craig, I ran my newly rebuilt turbo motor for 2 separate 40 minute runs before installing in car- Both runs with fresh breakin oil and extra ZZDP. First oil change oil was black, second change much better- third time still in car. Been running fine for last 450 miles--- knock on wood...

"A sign of great intelligence is being able to say 'I don't know'"
1966 Corsa Turbo Coupe
Now Located in Oswego,NY

I have heard that if you run the engine without a load that the rings will not break in correctly and glaze the cylinder walls. That said, the general advice is to run the engine 20-30 minutes at about 2000-2500 RPM (no load) to break in the cam/lifters. So..., apparently the walls don't glaze in that period of time.

Maybe a wives' tale, maybe important 70 years ago, maybe important today..., maybe not. Hopefully someone with more experience can advise. The type of rings used might be a factor.

I'm thinking a better cam break in would be an oil overfill and let it idle. The higher RPM is to splash oil on the cam.

Joel
Northlake, TX
5 Ultravans, 145 Corvairs and counting...

Thank you for all of the responses.

Wittsend: I’m using cast iron rings, so not sure glazing will be a big concern like it would be with chrome rings?

Pvholgado: I’m planning to change oil after timing and carb balance. It smells like it is running very rich, and I’m thinking I should deal with that first before polluting another batch of oil with cylinder wash. It will definitely get changed before install. ZDDP additive was used on the first run. I haven’t heard of the necessity for the additive after initial run. I have heard that there may even be a downside to too much zinc?

Joel: I did the oil overfill with an additional 1/2 qt to submerge the cam for the initial break in. Don’t remember where I heard that but didn’t see any downside to it. I seriously thought about making some plexiglass valve covers to view how much oiling was going on around the rockers without making a gigantic mess. I understand that oil flow to the rockers is a big reason to avoid idling before completing break in. Sure would be nice to see for myself how much of an issue it is on a new build. I didn’t have the plexiglass laying around so it became a low priority. Would be interesting to see how much oil flow drops off at idle. Maybe the next build?

Craig T
Central NY
1961 Tramp (truck with a ramp)

None of this "break-in" procedure was done on the assembly line. I, for one, do not think any of this is necessary. I have rebuilt many engines in the last 50 years and never had a problem with any.
Only my opinion, but I agree with GM.

Dennis
Nashville area

Get out there and beat the crap out of it.

Thank you Dennis. That is an interesting take. You sound pretty confident in your work. That’s good. This isn’t my first engine rebuild, but it is my first Corvair rebuild.

There is a video of Corvairs and Corvair engines kicking around on YouTube that shows completed Corvair engines coming off the assembly line in Tonawanda and being hooked up for testing and monitoring. It’s unclear what percentage of manufactured engines were tested and monitored. GM might not have broken in every engine, but there was an effort made to monitor some percentage of production during an initial firing. To me, the break in procedure is a method of directing and monitoring the initial firing. I agree that people over react and get carried away with it as if it’s a strict protocol that must be followed to the letter. I view it as insurance on all the hours and dollars that I’ve invested in it. In this case, it allowed me to identify a leak in the front seal area and avoid having to take the power pack back out again to fix it. YMMV.

Craig T
Central NY
1961 Tramp (truck with a ramp)

With stock valve spring pressures it’s not as critical as a race motor. Still just because GM Didn’t break them in doesn’t mean you shouldn’t

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

corvairsince70 Wrote:
-------------------------------------------------------
> None of this "break-in" procedure was done on the assembly line. I, for one, do not think any of this is necessary. I have rebuilt many engines in the last 50 years and never had a problem with any.
> Only my opinion, but I agree with GM.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

I used to say the same thing until the oil formulation changed. Even using the diesel oils I now do a 20 minute run in with ever so slightly over full on the oil. After that I set the carbs and install in the vehicle.

Below is something I wrote a long time ago for customer break-in procedure;

HCC Break-in Procedure

1. After installation, oil full, prime the oil pump manually or crank engine with the plugs out long enough to get oil pressure, stop. Let starter cool for 2 min.

2. On initial start-up, DO NOT race engine- but run at 1500-2000 RPM for 20 minutes, this is just a little more than the carb fast idle. Let engine cool for 20 min.

3. Restart engine, run long enough to adjust carb., and fully warm engine to get coolant circulation- Stop engine and let cool for 30 min.

4. Restart engine, let run on fast idle long enough to do final carb. and timing adjustments at normal operating temp, usually around 15 - 20 min. of running. Stop engine let cool and do a thorough visual inspection of engine. Correct any problems now or contact Ken @ Handy Car Care for any warranty repairs if needed.

5. Restart engine and let it come to normal operating temperature, with engine operating correctly you are ready for the first drive! Accelerate at a moderate throttle, DO NOT hold throttle fully open until shift point, for turbocharged engines absolutely NO BOOST. Go only a block or two and return to garage, stop engine, let cool, and do a visual inspection for any problems, and correct any you find.

6. Start engine and let it warm up for at least 5 min. then go for another drive along the same shtort route as before, this time use moderate to full throttle for short periods, but not more 3000 RPM, on turbo engines keep boost to a minimum. Return to the garage, stop engine and do a visual inspection again.

7. You are now ready for a longer drive as long as everything has been ok until now. Go as far as you feel comfortable in going with the engine- Do not baby engine, do not be afraid to use full throttle, but stay under the 3000 RPM limit, no matter how tempting it might be to “ let er rip”. On turbo engines still keep boost to a minimum. As long as everything was satisfactory on the previous drives you are now ready for step B.
B. You are now ready for normal driving, heeding prior warnings about engine speeds. After the first 100 mi. you may exceed the 3000 RPM limit for short periods but no longer than one gear. On turbo engines still keep boost to a minimum, under no circumstances should full boost be attempted. At 500 mi. change the oil!

8. You can now operate the engine within the operating limits established by the manufacturer. On turbo engines full boost can he used for very short time, then fully backing out of the throttle afterwards to let things cool.

9. At 1500 mi. after the first oil change, change the oil again, you can now establish a 3000 mi oil change interval. With turbo engines you can now operate within the limits as established by the manufacturer.
HAPPYMOTORINGI

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Thank you Ken. I saw that written up in your original post. It just didn’t seem like I’ve ran it enough to let it idle in order to set the timing. Not the first time I’ve been guilty of over thinking things.

Craig T
Central NY
1961 Tramp (truck with a ramp)