Tom's way of breaking in new motor

A highly debatable topic abroad so everything below is IMO (In My Opinion)

4 cycling a motor while driving on a track would maintain super cold temps due to air flow and large volumes of fuel passing through it. Thus not allowing the sleeve to expand and increasing wear greatly between the piston/sleeve and abuses the rod severely.

4 cycling a motor on a starter box or engine stand while adding heat (running it wot, wide open throttle, super rich) to me is fine since I am monitoring the temps and adding heat via a tile heat gun (Like this) as to maintain 200 degrees of head temp while 4 cycling it. A tank takes me less than 2 minute to run through my motor while doing this. I only do this 2-3 times then off to the track to enjoy. Works like a charm for me....

Procedure:

I tear my new motors apart, inspect, thoroughly clean, check head clearance, etc and then put them back together and seal the carb base, bolts and back plate typically with a O2 safe gasket material or something like Racers Edge air seal. Toss on the motor mounts, pipe, clutch and drop in the car.

I add 2 full turns or so to the top end needle adjustment (HSN), wrap the engine head with aluminum foil then warm/pre-heat the motor all around with my tile gun till I see 180-200 degree f of head temperature, then I plug the exhaust tip and turn the motor over to prime it and then install the glow plug igniter and light it off. I bring the throttle up to full slowly being sure it won't clean out and that I don't need to add more turns to the top (HSN). Then hold it clamped full throttle till it just about runs out of gas less than 2 minutes later typically.

I remove the wheels when I do this too. But I guess it doesn't matter.

You should have it fat (rich) enough that the wheels won't hardly even turn. I typical do 3 tanks or so letting it cool to room temp in between each running.

I lean out the top (HSN) some before each run to bring the revs up a pinch more and the temps. But still never allow the motor to run beyond 40% max RPMs. I make sure it stays loaded (very rich and 4 cycling) pretty good. I do this with the remote in one hand doing throttle and the other hand adding heat/checking temps with the gun. If it starts to clean out a little I just back off on the finger a pinch or add more to the top needle. Then off to the track to start tuning it in. Typically I run a couple light tanks at the track with no long hard pulls on the throttle and after that I tune it to win the race.

I have used this method on my last 5-6 engines and have yet to see a early failure or anything ill in conjunction with breaking in my motors this way. It is fast, simple and seems to get the job done IMO.

This site was last updated 11/24/06