Originally Posted by jt415gz
rjr - have fun with the break-in because I am leaning towards this method...will be a learning experience for me. I might actually go as far as to use a Hudy Break-In Bench since it is equipped with a propeller for load, cooling efficiency and save my chassis some bearing life
let us know how your break-ins goes...
I'd like to hear about it!
To Both RJR and JT:
I can vouch for Josh's method of breaking in engines. I agree with Rich, This is a good method if done carefully and patiently. It "works-in" the piston ans sleeve under a controlled environment. I have been breaking in my engines this way for a while now. I spoke to Josh about this process and he said it works for both AAC and ABC motors alike.
A few important observations before breaking in the motors that I have aquired and used in addition/combination to this proceedure. The motors have been faster, more consistent, and last longer:
1-Use a break in bench for the first 2-3 bottles.
2-add 7 oz of castor oil to the first bottle, 5 oz to the second bottle, 3 oz to the third bottle, 0 oz fourth bottle.....
3-Add a .10 shim to the underhead before you start the engine for the first time until you finish the fifth-sixth bottle then return to stock shimming.
4-Wrap the colling head (on the bench) in aluminum foil to maintain heat in the engine (good temperature for break in is 180-200 F) the entire time. Remenber that a propeller is blowing on the engine which will tend to reduce the temperature. You don't want that. You want to maintain a consistent 200 degrees.
5-EVEN BEFORE STARTING THE ENGINE, GET THE MOTOR'S CRANK CASE UP TO 200 DEGREES with a heat gun) this will expand the new sleeve and reduce any stress on the newly "married" piston and sleeve. This will also reduce the possibilities of the piston developing micro-scratches due to it being forced into the "tight" sleeve without heat and "lubrication". Sorry for the inuendos but its true.
6-bring the piston down between cool-downs. This allows the sleeve to recontract.
7- If the motor doesn't want to keep at the 200 degree point while running it wide-open, (because it is very rich), keep the heat gun on it pointed around the exhaust outlet right on the crank case forcing the heat to remain present.
8- Always keep measuring the temperature throughout the process
The key is to get plenty of consistent heat (around 200 degrees) into the engine with plenty of lubrication throughout this process on the bench and later on the track.
Enjoy the break-in!
Any question please don't hesitate...