Inliners International Forums General Discussion Engines Sustained rpm after break in

I'm still breaking in my new 261 around town right now and am wondering what you guys recommend is a safe milage to wait before going on a 250 mile freeway round trip around 2500-3000 sustained rpm.
I got to climb about 3500 feet of mountains where I want to just stay around 2000 rpm.

Engine is close to stock with .060 bored cylinders, cast aluminum pistons, standard rings, 254 duration cam and milled 848 head.

I try to run a newly built engine at various speeds and loads for the first 500 miles. I don't baby the engines but I try to avoid long stretches of steady highway driving during that time. Even on short highway runs I will use some slow down and then full throttle acceleration burst to put vacuum and then pressure on the rings. Hardest part of that is not getting rear ended when slowing or having some joker think you want to race when accelerating.

I do the same as Mike G. for about 3 heat cycles. Drain the oil and put in what you want to run. Far as I am concerned its ready to go. To me the heat cycles are the most important part of the break in. Taking the metal from dead cold to about 250 degs. and back to cold is the only way to seat the rings to the cyl walls. If the bearings have the proper clearance they are ready as soon as they have good oil flow. To get the heat in the motor you will have to block off the radiator some to get the heat up to 230/250. The first heat cycle in done in the shop after start up during cam breakin at 2000 rpms for about 20 minutes...SCRAP

250 degrees??????I don't know of anyone who lets there motors run that Hot. I know i have never run any of mine to that point. I run a 180-190 stat. Even when I brake a motor in(first fire up)
I do with out a stat and shut it down Once the motor hits 190-200 Then Install the stat and Finish The Start-up Brake in. Then I replace the
oil & filter then run it for about 200 miles and Change it and filter again. After That I drive it like i would any other day. my 2cents and it works for me.

Makes more sense,,,,not sure about the previous post???

MBHD

Well hank I have always broke my motors in that way since the 70s. I was once been told by my engine builder back then YOU brake the motor in the way you intend to use it. And I have NEVER lost a motor yet.

Let me restate what I said..."What I Do" on the first in shop run is to get it hot enough to boil the water 220+. An engine's initial run should be used to bring oil and coolant up to temperature , with little or no load, then shut down and allowed to cool to ambient temperature. This is important. After each run the engine needs to completely cool down to ambient temperature. After a cool down period, start it up again and take the ride as Mike G said "I try to run a newly built engine at various speeds and loads for the first 500 miles. I don't baby the engines but I try to avoid long stretches of steady highway driving during that time. Even on short highway runs I will use some slow down and then full throttle acceleration burst to put vacuum and then pressure on the rings." I JUST HAVE HAD BETTER LUCK WITH USING HIGHER TEMPS DURING THE FIRST 2/3 HEAT CYCLES. I just think that 75% of the cyl. wall to ring sealing happens during this time.The more oil that you suck up on the cyl walls driving around slow and lugging the motor at 160/180 temp. is just going to glaze the walls. Just remember guys "I AM JUST ANOTHER GUY WITH A OPINION" SCRAP

Hey scrap
I just have to ask you this them If i didn't deside to Make up grades to my 250 That I raced For 17yrs (about two years of that 17 as a daily driver) with NO tear downs And the bearings, rings
Cam still In A one shape. As a daily driver this
motor was Pushing between 13-15-1 compression
When I desided to use it more as a racer I dropped
the compression To keep from replaceing the head gasket after 3-4 runs Because I didn't have studs in the block.Because Most events I went to were at least 2-3 day events.
The Motor was broke in with 10w30 first fire up
no stat temp around 190-200 TOPs 20-30 min run
time Shut down Stone cold Install stat changed oil & filter. Refired Back to 190 run another 20-30 again 10w30 and Cooled.Refired and 50 miles at varying mph 30,40 50,60 Repet ,bring home change the oil and filter 10w40 for then Next 100 miles
changed everything again.Ran it again varying mph.
Then at about 200 miles or so There after It seen
nothing but 20w50.That motor was built with a
583/607 mech cam and ran like i said between 13/15-1 compression, Yes it was my Daily driver
it had a 4speed and 3:08 gears and I got about 16
mpgs city. as long as I didn't have my foot stuck in the carb.LOL And it also seen weekend track time.But come monday I was putting in a new head gasket.But as long as I didn't rpm it Like i did
at the track I had no gasket issues on the street.
And I broke in My v8 things in the same manner.

The only time I have ever seen someone have a
issue getting rings to seal right Is when Chrome
moly rings were used With Out the right final
hone(cross hatch) in the bores. Personaly I don't
like chrome moly rings.
But i do understand what your saying, but my
personal oppion is I don't like to see any temp
much over 200 in my Motor.

Another thing I like to add Is I DON"T Used anti
freeze In any of my Fresh Motor Builds Till i am 100% sure there are no leaks Meaning No Oil to water or visversa.Because anti freeze can wipe out
the bearings on a fresh motor.
again just my2cents

Road Runner, I like your '48! I had a Fleetline. It should get you better looking girls than that. I agree with the heat cycle idea though I don't like to boil a new engine. The cam break in is critical,you're past that. Running it at various RPMs and loadsis the way I go.. I don;t change the oil/filter till theres a few hours on it. I resist my hot rod ways for a couple of hundred miles on it . Then I drive it the way its going to be used. The 270 I built in '78 did a 4,000 mile road trip last year. (Nevada,So. Cal. Texas & back) 65-75 mph If I could get it from under the snow I'd go again tomorrow!

That is why I commented that your statement makes sense.

MBHD

Thanks Beater... I love my coupe!
What everybody agrees upon during the first 500 miles is what I have heard from my machinist, friends and also a retired GM engineer I spoke to.

Got 250 miles already this way and I guess since I'm not getting any warnings, I should be fine after another 250 miles to take her out on the wide open roads.
I just avoid staying at the same rpm too long and take it easier when climbing.

Thanks everybody - interesting read as always on the Inliners forum.

More old engine builders QUOTES !!!

"When it come to engines If its .001 loose nobody knows.
But if its .001 too tight EVERYBODY KNOWS"!!

"The square root of speed is the amount of broken parts divided by expendable income, multiplied by hours worked. The sum of that is inverted by the smile on your face with the first sub 10 second pass"

"Impossible? Nah...just needs more development time"

These are not new...may have read some on the board.....SCRAP

Not a break in question, but does anyone know if a distributor from a 1949 216 will fit on a 1959-62 261?

No - they are different.

You can always post a new topic and may get more responses and opinions.