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Author
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Topic: BREAK IN PERIOD ?
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 11:46 AM
   
I was watching horse power TV , and , I am a bit confused. They did a 500HP build on a AMC 401 to run on pump gas. After getting it put together they took it to have it put on a dyno. It seems that they did the 2000 rpm , 20 - 30 minute cam break in. Then they took it up to max rev to see the HP and torque. I was always told that this is the best way to mess up your new engine. I was under the impression that you had to have at least 1000 to 1500 miles on it before you went ahead and punched it out. So my question is , can somebody give me the proper method I should use to break in my completely rebuilt 289 , I hope to flash it up this week by thursday or friday , as time from work allows. It is a very mild build with a 268h cam and all parts ( new ) to match the cam. I am expecting 265 to 275 horse out of this engine , just about right for Cathy to cruise and enjoy. She made it pretty clear she wanted an easy driver. I look forward to all of your responses  JOHN ------------------
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V8 Thumper
Gearhead Posts: 4681
From: Phoenix, Arizona
Registered: Dec 2001
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posted 05-05-2002 12:50 PM
I've allways followed the specific cam manufacturer's break-in procedure... they seem to vary a bit. Some say 2000 RPM, others 2500+; some say 15-20 minutes, others 20-30. Go figure. I've allways run 30W ND oil for break-in, but I just read an article recently advising against non-detergent motor oil. I'm not much help today, am I?I personally wouldn't pin the throttle, at least not right away. Don't baby it, but I'm not real big on simulating dyno pulls on a virgin motor.
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 05-05-2002 12:56 PM
Once the cam is broke in, I have no problems with giving it he!!. Since my drag car is a race only vehicle, I cant very well take it out and drive it to put some miles on it first.
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 01:09 PM
quote:
Originally posted by kid vishus:
Once the cam is broke in, I have no problems with giving it he!!. Since my drag car is a race only vehicle, I cant very well take it out and drive it to put some miles on it first.
Since mine is not a drag car , what are the rules I should follow , for my street cruiser ? There are so many schools of thought on this issue , that I am confused , can anybody give me a course of action ? JOHN ------------------
65 2+2 FASTBACK
68 COUPE
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 05-05-2002 01:19 PM
quote:
Originally posted by johnmustang:
Since mine is not a drag car , what are the rules I should follow , for my street cruiser ? There are so many schools of thought on this issue , that I am confused , can anybody give me a course of action ? JOHN
I'm no help. On my street car I used to drive a little bit being fairly easy on it, (not more than 100 miles), then give it he!!.
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 05-05-2002 02:12 PM
This is a question that can cause loud 4 letter language among engine builders.
It is generally accepted that 2500 RPM is the lowest speed to run the cam in and highest speed to not overheat the rings in the process, 30 minutes is the shortest period for the cam and the longest for the rings ect.
It's best done when the outside temp is low so you can keep the engine temp down and do it all in one run.------------------
Of all my relations I like sex best.
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 02:22 PM
quote:
Originally posted by Larry Jennings:
This is a question that can cause loud 4 letter language among engine builders.
It is generally accepted that 2500 RPM is the lowest speed to run the cam in and highest speed to not overheat the rings in the process, 30 minutes is the shortest period for the cam and the longest for the rings ect.
It's best done when the outside temp is low so you can keep the engine temp down and do it all in one run.
But , how many miles should I put on the car before I start to punch it out , and , play with it ? How should the car be driven during this ( ? mileage ) break in period ? JOHN
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65 2+2 FASTBACK
68 COUPE
87 TAURUS WAGON
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 05-05-2002 02:47 PM
After the cam gets broke in I drive stuff mellow for around 3 to 5 miles to make sure most of the parts are gonna stay attached and then treat it like it's gonna get used for its life. About the only rule is don't let it sit and idle for more than a long stop light when it's new, for that matter if it's a motor you like don't let it sit and idle "ever" for very long .------------------
Of all my relations I like sex best.
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 05:58 PM
quote:
Originally posted by Larry Jennings:
After the cam gets broke in I drive stuff mellow for around 3 to 5 miles to make sure most of the parts are gonna stay attached and then treat it like it's gonna get used for its life. About the only rule is don't let it sit and idle for more than a long stop light when it's new, for that matter if it's a motor you like don't let it sit and idle "ever" for very long .
Then why do so many people say that you should take it easy for the first 1000 to 1500 miles , I am getting very confused , I really apreciate all the info , but , still not sure what to do. JOHN ------------------
65 2+2 FASTBACK
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98 F150 XLT TRITON V8 4.6, 4 WHEEL DRIVE
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 05-05-2002 06:13 PM
Some practices go back to the old way for a lot of reasons, with todays metals, lubrication tech and machining finishes the old break in prcedures are redundant, do it your way, putting 1500 "break in" miles aint gonna hurt anything. I'd just consider it 1495 dates without a feel  .------------------
Of all my relations I like sex best.
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 06:18 PM
quote:
Originally posted by Larry Jennings:
Some practices go back to the old way for a lot of reasons, with todays metals, lubrication tech and machining finishes the old break in prcedures are redundant, do it your way, putting 1500 "break in" miles aint gonna hurt anything. I'd just consider it 1495 dates without a feel .
Talk about being left high and dry  , can I then assume that even though the block is the original one taken out 60 over , that it will not hurt anything by just going for it after 10 miles. JOHN ------------------
65 2+2 FASTBACK
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 05-05-2002 06:39 PM
In the past I have done normal cam break-in, shut it down and drain the oil hot, pull off the filter. I let the engine cool to room temp, pour in some fresh oil, start it and set the timing, do the usual carb idle adjustments. At this time I would usually do a leak down test, this is a good indicator of how "set" the rings are. If the leakdown is still high I will run another break-in cycle and check it again.After that, drive it like you stole it. ------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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johnmustang
Gearhead Posts: 6197
From: British Columbia , Canada
Registered: Nov 2001
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posted 05-05-2002 06:47 PM
quote:
Originally posted by jkilroy:
In the past I have done normal cam break-in, shut it down and drain the oil hot, pull off the filter. I let the engine cool to room temp, pour in some fresh oil, start it and set the timing, do the usual carb idle adjustments. At this time I would usually do a leak down test, this is a good indicator of how "set" the rings are. If the leakdown is still high I will run another break-in cycle and check it again.After that, drive it like you stole it.
I know that this will sound stupid to you , but , what is the best way to do the leak down test ? What results should I be looking for. JOHN ------------------
65 2+2 FASTBACK
68 COUPE
87 TAURUS WAGON
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SteveLaRiviere
Administrator Posts: 45869
From: Saco, Maine
Registered: May 99
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posted 05-05-2002 06:48 PM
This is a case where common sense should rule. A racing engine gets stressed right after cam break-in. It also gets 'freshened' or rebuilt every year. You've built a mild small block and my guess is that you don't want to do it again next year, so I'll tell you same thing I told the people I built engines for. Start the car up and immediately bring the idle up to 2500 for a 1/2 hour. This gives your cam lobes the splash lubrication they need while they are being burnished in. Keep a very close eye on the cooling and do not let it overheat. Before you start it up make 100% sure there are no leaks.
After the cam run-in period, change oil and filter. That gets rid of most of the break-in lube and material the rings and bearing will drop off as it runs in and 'clearances' itself.
Start driving it and avoid sustained highway speeds and stop and go driving. {both heat producers} Country roads are best. Change oil and filter after 500 miles. Give it another 1000 miles, change oil and filter then drive it like you intend. Oil types are like opinions, but I use the same oil from day 1 that I intend to use once it's broken-in.
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 05-05-2002 08:36 PM
No such thing as a stupid quesiton. A leak down test is done with a leak down tester which is reall just two compressed air regulators and a couple of gauges. You screw a fitting into the spark plug hole, you hook a souce of compressed air up to the tester. It measures the pressure being held in the cylinder versus the amount of air it is applying and gives you results in a percentage. A leakdown test should ALWAYS be done hot, your engine runs hot right? Why test a cold engine? You should not dump anything into the cylinders through the spark plug hole like oil. You engine is not normally run with oil being dumped in is it?A good engine should show 4 to 7% leakdown and no more. 10% is getting bad, and 20% is totally shot. A new short block will have lots of leakdown, and when I see numbers in the 4 to 7 range, I consider the engine fully "seasoned". Oh, and I almost forgot, break the engine in with a straight 30W non-detergent oil. That is what most ring makers suggest. ------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big" [This message has been edited by jkilroy (edited 05-05-2002).]
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65_302
Gearhead Posts: 265
From: Bixby, OK
Registered: Jul 2001
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posted 05-05-2002 11:37 PM
FMR gave us these tips (for the 302 XB3): cam break in should be 2000 rpm for 20 - 30 mins. Drive the car for 750 miles at varing speeds below 55 mph and below 4500 rpm. I would guess each engine bulider has their own numbers. I would say, do it their way.
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