I have a rebuilt 350 which i am about to start up. I heard to rev it at 3000rpms for 10 minutes to break the engine in. Is this true? Why is it necessary? thanks
jon

its 2,000 rpm's for 20 minutes and its for breaking in the cam shaft , let the engine fully warm up before doing this and check and adjust timming ,, then drive car and acellerate quickly to say 60 mph then decellerate back down to say 30 mph <no brakes> and repete this cycle several times , this helps break in the piston rings what this step does is load up the engine <like a Dyno> and then when you back off it helps lube up cylinder walls good also gives you a shot at another hard aceleration

[This message has been edited by catman (edited 12-04-99).]

You here all different things. The most common I have heard is hold it at 2500 rpm for 20-25 minutes. This is done to break in the cam, more specificly to get the cam and lifters "wearing in" together properly. This is a VERY IMPORTANT part in the proccess of getting your new motor running. You want to get the motor running as soon as you can. in the best case, you get your timing set close enough before even starting the engine, that way nothing interupts this break-in of the cam. DO NOT set the idle fast, and go do something else while your cam is breaking in. You really need to be watching all the vital signs of the motor, as well as watching for leaks etc. Sorry to run on, but I had seen a few posts here where people had sounded as if they ignored the engine while it was breaking in. You want to break it in, not break it. Good luck!

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Steve

72 Chevelle SS402/4sp

I dont have my trans hooked up, so I have a jack holding up the engine from the oil pan cuz the engine will fall back if I dont. Should I hook up the trans and drive shaft?
I'd rather not because my car is pretty much in pieces, no fenders or fender wells, hood, no interior.
Jon

By the way, I am running open heads. SO my neighbors are gonna love that sound for 20 minutes. I hope they dont call the cops, neighbors are kinda fossils..
Jon

The info provided with the cam should tell you the recomended breakin... Contact you cam manufacture if you can't find their instructions. Cams tend to go bad in the first 50 - 100 miles. Do it right, you won't regret it! I have never seen anyone warm up the motor before breakin. Breakin is a turn the key and get the revs up now deal! The only reason to stop during this time is if you have a gas leak or no oil pressure.

Be safe and smart, don't try to fire it up with the floor jack holding the motor up! Finish your install first. You will have plenty of time to fire it when done and you will be on the road sooner after firing it up that way. As for the noise give your neighbors some warning and let them know it's heading to the muffler shop asap after breaking in the cam. I hope you ment open headers when you said "open heads". Good luck and have fun!

Is there a particular reason that you need to light up the new engine now, other than the fact that you are like the rest of us and are anxious to hear your new engine sing? Otherwise, it may be more pracitcal to wait until the tranny is buttoned up.
But whatever, basically what you need to do is prime the oil system by spinning the oil pump (with a drill and some type of shaft such as an old modified dist), attempt to be sure that everything is set close enough for the engine to fire right away. Once it starts, turn the dist until the engines "sounds" good, run the rpm up to "around" 2500 (the exact rpm is not critical) and just let it sit and run for about 20 min. AS SOON AS POSSIBLE check the oil gauge to be sure you have good pressure. What you are doing here, as mentioned by others above, is breaking in the cam. In 99% of all cases, this is where you "make or break" a new cam. After your initial 20 min cam breakin, you are good to go. There are as many opinions about how to treat a new engine after this as there are engines. With todays precise tolerances and lubricants, most people seem to feel it is OK to let 'er rip right out of the gate. Myself included. I won't advise you about how to break in the new engine, except for the initial cam breakin as I described, and almost everyone universally agrees about this.

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Tom Parsons

This is my first rebuild, so yeah, I guess I am more than anxious. When I tore the car apart, I dont remember how the clutch hooked up. I know the disk goes between the flywheel and pressure plate. Do you put the throughout bearing inside the pressure plate before mounting it to the flywheel? What can I do to align the disc if I dont have an aligner? It doesnt show in any of my rebuild books.
Jon

Jon,
This is just my opinion as an engine builder....do not start the motor until you are ready to drive the car out the door. It is impossible to properly break in a motor without getting some load on it. If I had built it, I would tell you to let it sit until you can drive it, even though I hate to see a new motor sit forever.
The only correct answer to this is to call your engine builder and do whatever he tells you. He is the one that will have to stand behind the motor if there is a problem in the future.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

jonjon00, sounds like you are pretty excited to hear it run. Follow the good advise above and wait until the clutch, transmission and driveshaft are in the car. It does sound like you are a little confused about the assembly order of the clutch assembly. Find someone with some experience in this and ask them to help. There are a lot of manuals that will help also. Since you rebuilt the engine, you might have a different crankshaft. Make sure that there is a pilot bearing in the transmission end of the crankshaft. This is for the input shaft of the transmission. After the flywheel is bolted on, the pressure plate and clutch is next. Make sure that the springs in the hub of the clutch disk go toward the transmission and not the engine. Before you tighten the pressure plate bolts, insert the clutch alignment tool through the pressure plate, clutch disk and into the pilot bearing in the crankshaft. Wiggle the alignment tool in a small circle to make sure the clutch disk is centered and tighten the pressure plate bolts. It's now time for the bellhousing. Make sure that the clutch release fork is clipped onto the fork pivot ball in the bellhousing. You might also want to look at the pivot ball to see if it is excessively worn. A new one is available at GM. If you need one, take your old one to the dealer to make sure you get the right one. Now you can mount the bellhousing to the back of the engine. The throwout bearing is then inserted into the two fingers of the clutch release fork with the big end toward the pressure plate. You're now ready to install the transmission. It makes it easier if you have some alignment pins. Get a couple of 5" long bolts the same size as the transmission to bellhousing bolts. Cut the heads of the bolts off and using a hacksaw, cut a screwdriver slot in the end. Thread these into the bottom two bolt holes in the bellhousing and use them to guide and support the transmission as you are installing it. After the transmission is in and seated, insert the upper two bolts. Unscrew the alignment pins and install the bottom two bolts.

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Bob Murray 66 Malibu
Greenfield, Indiana (Indianapolis)
TC Gold #49
Aces #01941
NCOA #20838

Also, when you're 1st ready to start up, have all of this close at hand:
Fire extinguisher!, water, antifreeze, oil, a good helper (watch those gauges!).
I'd also have a fan handy to blow air thru your radiator just in case the stock fan isn't enough for the 1st 20 minutes.
I always run mine for 20-30 minutes at 2500 rpm. Then change oil & filter, adjust lifters, finalize timing and carb, and go riding! Good luck and don't rush it!

mine will be in at christmas i hope and i already have BUTTERFLIES when i think about it (first time builder too)

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members.aol.com/jnkb2cool/chevelle9.jpg (http://members.aol.com/jnkb2cool/chevelle9.jpg) members.aol.com/jnkb2cool/350.jpg (http://members.aol.com/jnkb2cool/350.jpg)
John Krenn
1970 malibu SS look-a-like well kinda
307/200-4r (soon to be 355 or 383)

Ft.Worth, Tx

Can't stress it enough, follow the cam manufacturer's instructions to the letter. If the instructions say to stand on your head and chew bubble gum during the cam break in period, then do it. After the cam is broke in, then continue to break the engine in according to the engine builder's instructions.

My neighbor just went throught this with a new small block.He had 5 lifters that were wore and 2 had worn holes in the bottom.It still ran!Follow the cam manufactures specifications exactly!

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John 67SS
ACES #2887
Team Chevelle Gold #127
Bassett,VA




[This message has been edited by 67ss (edited 12-05-99).]