Breaking-in of Race engines?

[Trans Åm]

First off, I've only rebuilt one engine, and assembled one other. I have had quite a few years since then to read and ask mentors and learn about building engines and I always recollect the essence of breaking in an engine. NOTE:"Full" rebuild done in well equipped machine shop at local college--did any/all required machining myself. Very neat experience, indeed.

I have come to understand--either correctly or incorrectly--that camshaft break-in is tantamount. There is also a method for "setting" piston rings. These two methods are done upon immediately firing the engine and immediately driving the car, respectively.


However, there seems also to be one more step of break-in, more of a rule-of-thumb "grace period" type break-in for the engine as a whole unit.  Typically it goes something like, "drive 500 miles, then replace oil/filter--do not exceed 3/4/5000 RPM;limit/avoid use of Wide Open Throttle" That is a pretty general description.

So here we have a minimum mileage requirement(most say 500-1000 miles), AND we have a performance limitation: most tell you to not push engine hard, and keep RPMs low for duration of initial break-in mileage.



So what did race teams do when they needed to race their engine like mad men the next day? I don't care if Traco or Bartz built your engine, or if it was Al Richards and his buddies


What was the procedure to keep engines alive? I have a funny feeling Donohue didn't exactly take the Penske Camaros out for a 500 mile stroll the day before a big race with a new engine, nor did Traco do it for them.

So then what??


Did Traco/Bartz/independents just not care? I remember an article stating Penske engines were only used for a couple races before a complete teardown. Did they just break in the cam and then send it off to be spun at 7500 for eight hours and just say "screw it" to engine break-in? Is engine breaki-in only important to ignorant little kids like me who only drive on the street?   



Thank you to anyone who may have insight, and apologies for my long-winded-ness.

[69Z28-RS]

This isn't specific to 'race engines' but it should be applicable as it's based on information I gleaned from a TransAm independent racer long ago.  I'm very interested if any other old racers follow any procedures drastically different than this...
- - -
I've rebuilt a number of engines over the last 40-45 years of my life, and based on that history, I have some opinions myself, although I consider myself still open minded to a different view as long as it's supported by some theory, logic, or fact..   My history includes:

o  assisting friends, as a 'helper', rebuild several engines in my early 20's, ranging from VW 4 bangers to 426 hemis, but with concentration on erly small block chevys.
o  When in engineering school in the early 70's, I met a Trans-AM, IMSA GT car owner, builder, driver (Robert A Christiansen) when he was asked to give a talk on 'engineering materials used in auto racing.   As a result of that, I ended up hanging around his shop, helping him on weekends and evenings, and generally trying to learn as much as I could from him, as he was one of the most 'practical mechanical engineers' I'd ever known, even to today.   He was an IBM engineer/manager at that time; a part-time racer, and ultimately retired from IBM.
o  in 1974 I bought a '68 Z28.. worked on it and drove it daily until '76 when I traded it for my present 69 Z28, which needed an engine rebuild, so naturally I asked Robert (Bob) for assistance.   He let me rebuild the engine in his shop; he told me what to purchase, he went to the machine shop with me and provided guidance to the machinist, but did not do any of the hands on work, instead he told me at each step what I needed to be doing and why..  so that experience formed the basis for most of my opinions on engine rebuilding.   I've rebuilt several (10 to 12 small blocks, and 1 BB 454) for friends since then, and a few of my own all using what I learned from that experience with Bob.

Things I learned from him were:
1.  For 'racing' build your engine on the 'loose' end of the tolerances ie. piston to wall and bearing clearances; basically it gives your engine a head start on the break in and reduces internal friction, and you're not looking for 100,000 miles of wear out of such an engine.
2.  Ensure that the oil returns are opened up; small block chevy oil returns typically have casting flash which restricts oil return.   Grind all those out in the ends of the heads and the lifter galley after tear down.
3.  CLEAN CLEAN CLEAN.   Hot tank is not enough.  You'll be amazed the first time you get an engine block back from the hot tank if you use a hot water pressure blaster to blast out all the water jackets..  you'll see metal chunks, rocks, etc..  come out!   USe hot water, detergent, and properly sized engine brushes to clean all surfaces of the engine block.   Obviously you should chase all the bolt hole threads before cleaning also.   After the cleaning and drying, coat the cylinder walls and lifter holes with oil or grease to protect against corrosion, and PAINT all the cast surfaces in the lifter galley, under the timing cover, etc..   in order to capture/hold any residual grit/sand/etc from the factory casting process.   I've always used Rustoleum (qt can will do many engines).  I use black or red so that any bearing material will show up 'silvery' against those colors.
4.  During assembly, liberal use of Molybdenum Disulfide on all 'metal to metal' friction surfaces such as lifters to cam, rocker balls/rockers, etc..  ie. high load, high speed, steel on steel surfaces (not bearings).  I also disassemble the oil pump, and polish all the frictional surfaces on the moving parts, and also use the moly on reassembly.  Lock tite or safety wire the fasteners; braize the pickup tube in the pump cover plate, after setting proper gap to the pan.
5.  Use plastigage on all the bearings with one drop of oil to hold it in place, torque down, disassemble and record each value.  Ensure consistency in the values and measures you get across all the same type bearings.
6.  Pre-adjust valves by your favorite technique.   IT should be good thru the initial startup period.  
7.  Before initial startup, ensure a KNOWN GOOD distributor and carburetor are used - you don't want a malfunctioning, mal adjusted distributor or carb during first fire up or break in.   you have to ensure proper timing and fuel mix during this time.   Also before startup, use an external device to pump oil to all the bearings, and after this, I ilke to actually spin the motor a few times with the starter (NO plugs/fire) to circulate the oil and get pressure up.   Verify proper oil levels and water levels (hopefully you're using a known good water pump as well).   Ensure that you have a working oil pressure and water temp gauge before startup and AND NO LEAKS.

Prior to start up, clean/gap and install plugs.   Set initial timing so the engine will start immediately (this is easy to do - ask if you don't know how).
Prepare to monitor the engine speed, oil pressure, water temp during the initial 30 min run.   Don't do this in a closed up shop...     best is outside, because most of us don't have exhaust hookups to the outside.   Start the engine and run it for 30 min at 3000 rpm..  don't let it die..  if it's trying to, then increase rpm.    if you are using a known good distributor and carburetor, you should not have to be doing any significant adjustments during this time, but if everything looks/runs good, and you want to fine tune the timing or carb then do so, but don't neglect the monitoring of the water temp and oil pressure.

After the initial run it, take the car out and put some load on the engine.   I've always followed the 'break it in like you are going to run it' rule..
When I took the '69 Z28 out back in '76, Bob went with me.. and I was 'babying it' ..   he said RUN IT!@!   so I did..  up to 7000 or so but not in a high gear.   Load increases as the gear increases, so running your engine in low or second is not as heavy a load at a given rpm as it would be in a higher gear.   Main thing during the break in period to to not run it as a constant speed or load.  Vary the load and rpm during the first 500-1000 miles.    Change the oil and drive it...

[Trans Åm]

Wow, that is very extensive and useful information! Thank you very much Gary!
Do you know how long Bob ran his engines before he ordered a rebuild? Because he was an independent driver, he might have just ran them until they died, rather than have them on a schedule for teardown like a heavily funded factory team.

That would obviously be the way I'd have to do it as well, not to mention the fact that any engine/car I would run would only be tracked once ever month or so, and street driven the rest of the time.

Again, thank you very much.

[69Z28-RS]

No, I don't recall that if I ever knew it.   He built his engines 'conservatively', since he was an independent and had to fund his own car (with some assistance from local businesses here).   When he was running IMSA GT in the mid70's, he had both a BB (427) and the 302 which he switched depending on the track he was running, and I recall at one time he switched in the 427 from his tow vehicle when he broke the one in the car..  

[satman]

In my opinion the single most important thing you can do when building a race engine is find yourself the best machine shop that you possibly can and preferably one that specializes race engines only........... Have them line bore your block, mill the deck then hone the block with a torque plate attached ........The other important item in your build is the crankshaft we had ours custom ground to assure we had the correct  clearance for our Clevite bearings then we would send the crank out for nitride treatment. For our engines camshafts wear was not a big issue so we used a heavy weight oil on the journals and lobes but the one thing we always always did was to prime the oil pump with a drill before we fired it up.

  AL

[Trans Åm]

Thank you both Gary and Al, very cool especially coming from two people with "independent" backgrounds. Much more practical info for me and most others in the future.

[firstgenaddict]

1990-1992 I apprenticed myself 4 hours a day to a race engine builder who worked with Les Ritchey and built the Cammer's for Gas Rhonda etc, his name is on the side of Gas Rhonda's car below Ritchey's. Cliff Brien

Combined Gary and Al have the procedures pretty much outlined for race engine prep, block prep, remove all flashing and irregularities from all the galleys, smooth the lifter valley, we epoxied screens in the returns, clean and round all edges, leaving no places for stress risers to form. The piston tops we rounded all sharp protruding edges, then dressed piston tops to help them take on a nice even coating of carbon, when the engine was assembled the piston tops looked for lack of better word "soft". Having pulled down many of these engines for freshening I can attest to its efficacy in achieving an even carbon coating which I was taught helps to insulate the piston crown. The smoothing of the sharp edges in the combustion chamber and piston crown are to mitigate detonation as sharp points can retain heat and become sources for pre-ignition. Detonation is two or more flame fronts colliding within the cylinder.

Surface the main caps and then line hone, as stated a solid bottom end is paramount to longevity and thus performance. You can go to billet splayed main caps (common in high po engines). We ran Callies non twist crankshafts and carillo rods exclusively along with zero gap rings, check your lifter bores, we used to go oversize then bush with bronze. All custom designed camshafts, if you can run a solid roller, DO.
Most of what we did were circle track engines with few monetary restraints some using exotic strokes and bores, titanium valves, whatever we could do to exploit class rules and maximize performance within the class, we did some drag racing and road racing builds from time to time, however the day in day out stuff roundy rounds.
Bracket Racing screwed up class exploitation.
Our engines completely assembled could be spun over with 7-9# of torque most of our competitors were 20#plus. Plastigauge and close enough are never ok. We used bore mics to measure ID's and std mics for OD's  everything was meticulously measured over and over. Cleanliness is next to Godliness in race car prep. 

WE fired all our engines, broke in the camshafts for 30 min, pulled the oil filter cut them open checked them, put on another filter ran for another 30 min and pulled it, if no large or excessive metal shavings were present they were ok'd going to run the normal race schedule, perhaps that evening.
We would be at the track if it were a new customer or maybe a big new build for a new race car where we were doing the carb setup, the dry sump, the ignition. The majority of the time when dialing in a new setup the customer rented the racetrack, that way we, along with their chassis guys could spend a few hours dialing everything in.

The road racing engines were mainly 260 280Z  straight 6, also callies cranks and carillo rods.
James

[Trans Åm]

Thank you for the input, I'm actually assembling an old 350 right now! It's a low RPM motor for a '67 chevy C50(two ton truck). But it is also my first real engine work in a few years, hopefully I don't screw it up!

I really take interest in this part,

WE fired all our engines, broke in the camshafts for 30 min, pulled the oil filter cut them open checked them, put on another filter ran for another 30 min and pulled it, if no large or excessive metal shavings were present they were ok'd going to run the normal race schedule, perhaps that evening.

I always wanted to know how soon customers were allowed to race on their brand new engines, and this is exactly what I suspected. Break-in→thoroughly inspect→RACE!
(not any of this "go easy for first 1000 miles" crap)

[firstgenaddict]

One other thing I remembered which maybe significant

We ran Total Seal Gapless rings and ran the top Gapless set (3 rings) and the Oil control ring (we never ran the 2nd ring, never not for any application including  street engines), unless running custom bore and stroke combos where the pistons were being made for us we ran a std 3 groove piston.

My father pointed out to me that the race engine rings were seated the following way,
When warming up the first time on track the driver ran around slowly up through 1st and 2nd then a lap or two into third gear, then started the break in once up to operating temp.
He would slowly accelerate up through the RPM range in 3rd gear, leaving it in 3rd gear back off the throttle slowly and let the car drag the engine back down to 1500-2000 RPM's, 20 laps or so on a 5/8 mile track over and over, I would say the run up and back off occurred 2 times maybe 3 times per lap. Inevitably before 20 laps was up the driver was running harder and harder. bring it in temp check individual pipes for lean rich conditions maybe pull plugs and jet carb... As long as everything stayed in the given set of parameters the driver was running hard laps with 20-25 laps on the engine... maybe 15 miles?   

At the top I was talking about custom pistons etc
I remembered this odd class where there were 2 different CUI engines allowed 311 or 355. The benefit of the 311 is you were allowed any stock 4 bbl (holley's included) vs running the 355 with any stock 2 bbl.
Whomever had factored the engines for the class evidently expected 5.0 Fords +.060 or 305 Corp GM's maybe 307 Chevys +.030-.040 over as the base engines for the lower CUI. (this was a hobby class BTW)

It was not a .030 over 307 we chose, It was custom combo, we ran a 4.125 or 4.25 bore (helps to unshroud the valves), which I think worked out to a 2.5625 or 2.625 stroke (Callies). A 6" Carillo rod and a short compression height piston with only the top groove and oil control groove and a narrow pin width. The piston weight was extremely light, the engine would rev to the moon quickly.  

In a class where most guys spent $2500 on an engine this was a $12,000 - $15,000 engine.

Prior to this a .060 302 Chevy would have killed the class, if for no reason other than the durability of the stock 302 parts. (no one ran this setup.... looking back I am really at a loss as to why they didn't.)

[Trans Åm]

VERY interesting. Not to say I am experienced, but I have never heard of only running the top ring! Thank you for the wisdom and effort, always good to hear more.

[firstgenaddict]

VERY interesting. Not to say I am experienced, but I have never heard of only running the top ring! Thank you for the wisdom and effort, always good to hear more.

We ran the TOP RING SET... The Total Seal set has one thin ring over and under the top ring, similar to how an oil control ring is set up, just with a ring in the center instead of the waffle baffle. A std top ring wouldn't seal well enough to run by itself.

Funny thing my ex father in law was rebuilding the engine in his 1905 Cadiallac, single horizontal cylinder about the size of a quart paint can. He had put it back together and it would run however didn't have enough power to pull the car up out of the drive way (5ft rise over 50 ft.)  He took it apart and I went over to help him reassemble it... we go to put the piston in and he lines the ring gaps up in line... I said is that how you put it together last time? Yes he replied.. I said no stagger them, he said I thought they would all work themselves to the heavy side on the bottom Ie gaps lined up across the top of the cylinder. LOL staggered the rings... more power than ever.

[Trans Åm]

Man you have some incredibly unique stories! Thank you for the clarification by the way.

Could you get that picture link in your signature to work? I'd love to see the pictures of those cars.

[firstgenaddict]

Pic link should work now...

I have been very fortunate, my father collects and restores vintage flathead fords so I have had access to tools garages and knowledge for my entire life. After learning to use a screw driver at 3 years old I removed every switch plate and door knob I could reach and met my dad at the door with a hand full of screws. My dad has a picture of me with my baby blanket in a 1940 Ford taking everything apart.

Here is a pic of me sandblasting my first car at age 12
~ 57 Chevy 2 door post with a 301 and 30/30 cam.

[69Z28-RS]

James, do you still have that B/A Sedan?  *G*

[cook_dw]

Pic link should work now...

I have been very fortunate, my father collects and restores vintage flathead fords so I have had access to tools garages and knowledge for my entire life. After learning to use a screw driver at 3 years old I removed every switch plate and door knob I could reach and met my dad at the door with a hand full of screws. My dad has a picture of me with my baby blanket in a 1940 Ford taking everything apart.

James, sounds like you and I grew up under the similar circumstances.  Growing up my father worked 2nd and 3rd shift and during the day would work on Camaros and other musclecars and we would always go out to junk yards and I would be handed flat head, phillips, 7/16, 1/2, 9/16" wrenches and told to got get bolts and screws while he pulled the larger parts..  I was his right hand man.  2006 I lost him and damn do I miss talking and hanging out with him.  But those memories will never be forgotten.