I was wondering what the proper engine break-in time is after a fresh rebuild. I know the cam needs to get a break-in of about 25 minutes I think but after that when should I change the oil if I even should.

Its got flat-top pistons with moly rings if that changes anything. Thanks for the help...

 

Change the oil and filter after the cam break-in.

While you are doing the break-in keep some large floor fans on it, to keep it from overheating.

 

coolmint,
If it was properly plateu honed then it will be almost broke in before you hit the street with it. Here is the methods I have used......
1. Warm it up all the way, and while it's warming use this time to set your timing and carb look for leaks etc...have a good oil press gauge in it while this is going on.

2. Drive it (sanely) to a stretch of speed limit 60 highway

3. Do 10 sets of 0 to 60 at full throttle through the gears. Don't rev it over say 3200 RPM. At the top of each burn let it decellerate all the way back down to 10 MPH, then start over again.

4. Then run it at normal highway speed back to your shop and recheck timing and carb etc

5 change the oil again between 500 and 1000 miles.

Remember you guys this is just my opinion there are alot of valid ways to do this.

I have a little over 3000 miles on my new 400 now and I love it. Which cam did you use? I have the Comp DEH265 in mine.


Ken

 

Thanks for the help.

Here is the list of everything so far...

400 block bored .040 over...wait should it be .40??
Comp Cams 265DEH
Badger Flat Top Pistons
Set of Energizer Roller Rockers
Rebuilt heads with 2.07in and 1.65exh included a massive amout of porting and a 3angle valve job
Cloyes Double Roller Timing set at 'straight up'
Edelbrock Aluminum Intake
Holley Street Avenger 670 Carb
Mallory Mechanical Magnetic Distributor
a set of Doug Thorley Tri-Y Headders
And Fireball Hi-6S Ignition Box

I hope this is a good setup, been working at it a very long time. I want it to work, a lot of money has gone into the rebuild and hopefully it will last a long time.
I should be getting some pictures of the engine before I put it in next week.

 

what ever you do while breaking in your cam do not let it idle. get right on it. you can adjust the timing close enough when the cam is breaking in. They need alot of oil and idling starve them while needing it for break in.

It is good to have 1 if not 2 extra people to help. one monitoring the guages and keeping on the gas, the other 2 checking for leaks and what not.

 

Should I do the break-in of the cam with or without a new thermostat housing??

And what RPM should I maintain it at while doing the break-in??

 

always run a thermastat. They were made for a reason.

Nothing under 2200 and I beleive when I was told by my cam grinder that wanted 2200-2500 with varrying the throttle.

 

take it to get dyno tested and keep it redlined for a good 10-20 minutes, also, while on the way to the dyno center, let the engine wind up as high as it will go before upshifting, drive like you are in a NASCAR race, and give the coppers a run for their money while you are at it. this will insure taht you will be able to have a good loving relationship with your new engine, while you stare at its blown up hull of wreckage in your nice comfy 5x10 room behind the newly installed tempered steel designer blinds, er bars.