Fuelman

My Feedback: (6)

Yeah, you are absoutly correct sir!!! They had more!! The older true ABC/ABN from the quality manufacturers of that day and vintage were so tight that many of them had to be heated with a propane torch to get them fired up the first few times. Some of the high end racing Super Tigre's, K&B's and later on the OS dutcted fan engines, ABN Webra's, MVVS's etc... Even today, the mark of a high end ABC/ ABN engine is how tight it is, the tighter the better. The K&B 48 is a perfect example of an engine that is generally so tight that my heavy duty starter would break the rod if it was not pre-heated.


If it's a true ABC/ABN/ABL type engine and after the first 15 or so minutes of break-in, If they still have hot pinch (assuming they are fully up to temp), then the engine is overcooled, not allowing the chrome plated brass sleeve to get to design thermal expansion to where it makes a zero clearance or near zero clearance fit to the piston. Any time you have an engine that is fully up to operating temp (not based on a temp gun, but based on how it is running), and it has noticable pinch at top dead center (not to be confused with compression), it is running too cool (overcooled), not to be confused with too rich.

Could not agree with you more....
Like I said above, if there is still a hot pinch, the engine is overcooled, this is what leads to accelerated rod wear or eventual breakage, and leads to premature piston wear. The people who design these engines design them knowing what the thermal coefficients of expansion are to the sleeve, and high silica-aluminum piston. They know how much radient heat loss is needed to keep these things in a proper operating tempreture range. But, that would be way too small according to the consumer and run way too hot according to the consumer. What these designers can not do is overcome the marketing efforts that have led the car people to think colder is better so we must have too much heat sink head area than what is optimal for the paticular design. Actually they are marketed that way for a reason- to sell parts. Ever wonder why the average airplane engine has a 1 ot a 3 year warranty, and the average car engine might have 30 days? These are magnificent marketing efforts to convince the public that the piston / sleeve / rod are normal short lifespan wear items. The marketing efforts are designed to give you the consumer a pre conditioning that the replacement parts are needed every 5 to 10 gallons.
Ever wonder why a 25 size airplane engine can handle 20 gallons no problem and more than likely 30 before needing parts? And believe me thay have a rougher life than car engines in many respects.
I have had many meetings and discussions with companies that make car engines, and have been asked to write operating manuals only to be rejected because it tought car guys how to get the most life from their engines vs. the car guys buying the most parts. The rc car engine companies have collectively told me in one form or another, that teaching you guys how to maximize the lifespan effectively kills their cash cow.

Listen guys, my objective is not to wind everbody up in a furrball, it is exactly the opposite. I want people to realize that what a lot of the so called experts feed us as gospel may or may not be correct.
I say that because I have absoutly no interest in selling model engines or parts for them once they prematurly wear out. It is the exact opposite, I make fuel for a living and when you have down time waiting for replacement parts or your day at the track is shot because your engine is shot you do not burn fuel.
So, I have every interest to give you the best advise and share the knowledge I have gained over the years, so your engines last longer and you burn more fuel.

Call me selfish.

downunder

While I agree that the best way to run in an engine is by using a prop to give some load, this isn't always possible with a car engine unless you have access to a lathe to make the extension necessary for the prop to clear the carb. In some cases a special prop nut also needs to be made. Failing that, the only other way to put a load on the engine is to drive it around. I also agree with Fuelman's post.

As for car engines having that huge pinch, their pinch is deceptive because of the quite small radius of the flywheel (about an inch). With a prop on a plane engine and hand starting I'm putting a force somewhere around a radius of 3-4" so it's far easier to get the piston through the pinch. Actually with even just a moderately fast flick by hand any pinch is then quite unnoticeable.

j_blaze

46u

My Feedback: (3)

I am far from and expert but know what works for me and once I find what works I stick with it. I guess I just do not know as much as some think they do. I expect others to do the same.

j_blaze

some out there have not found a break-in method they are happy with and are still looking. this could help.

SManMTB

This works really good too:

Add a tube of toothpaste to a quart of fuel. Start the engine and run it at WOT really lean. It's broken in before you know it.

46u

My Feedback: (3)

[sm=lol.gif][sm=lol.gif][sm=lol.gif]

j_blaze

j_blaze

got the new motor through 2 bottles today, metal to metal pinch is almost gone so at least it turns over on the box without heating first. pinch was ridiculous out of the box.

TRIPPLE A STRONG

IS THAT CREST OR AQUAFRESH ALSO CAN I USE THE MINT OR DOSE IT HAVE TO BE ORIGINAL

SManMTB

Crest, no doubt.

j_blaze

comedians

vnmsgt

This sounds very interesting but too much work for me. I like to idle my motors for break in this way I can walk away and do other stuff LOL! Guess I am too lazy.

j_blaze

i won't knock anybody on how they break-in their motors. vnmsgt, the granade was gonna idle forever when i was done, nice low steady idle. i think we will be very happy with these motors. i'll post more as she comes along. i hope to finish this gallon this weekend at wow or somewhere so it can wake up a bit.

SManMTB

Actually the tooth paste is not entirely a joke.
It works pretty well if it's done by hand. Smear somne paste on the piston and lap it in by hand (ie don't put it in the fuel).

JB COMP

Yeah, I know some people put some oil in the engine, and hook a drill up to the crank and spin the engine with the drill, and it breaks it in.

SManMTB

It's faster without oil.

j_blaze

alright, took the grenade out this morning in 59 degree weather and it turned over on the box with no heatgun. ran a full tank with one flame out, old plug. motor is crisp, smokey and only got over 230 once. after 1/4 gallon wot break-in success, again. motor is ready for the track now...

supertib

here how I Break my engines in.....been doing this for a few years and have amazing engine life...... this video is edited of course, but you get the idea

http://www.youtube.com/watch?v=VuP0H3Ot1lM

j_blaze

whats that starter for, just flip the prop. that would be ideal but look at all the fabrication to make one of those, and how to get the prop on the motor? and that finger control, i need something a bit more precise. cool tho.

bikeracer

When I run my engines with a prop on I rig a servo up to the throttle and stand at the back of it using the TX when it's running.

.

j_blaze

alright, after first race weekend with the motor, it is very good. great bottom and mid but i think the pipe choked the top a bit, we'll see. i however forgot to ziptie the air filter during practice. i have never done that before. the motor ran flawless the whole day but after i cleaned it out and ran a tank the metal to metal pinch was gone. i had struggled to turn it over cause of the flywheel before that tank, little dremel on the chassis took care of that, so it still had some metal to metal pinch before the filter fell off. right now it has good pinch but drastically less than that morning. not sure how long the filter was off though before it fell out of the chassis. guess i'll have it re-pinched if it starts acting up.

SManMTB

epic fail
suck when that happens

Fuelman

My Feedback: (6)

Before you try repinching, take a real close look at the piston and insure it wore evenly and is not scared up from dirt ingestion. I have seen a few guys try the repinch thing only to find out that the piston wear was too uneven to make it worthwhile.
Reason I say that is when dirt ingestion leads to wear, the piston wears the most drastic at the location of the intake ports. If the wear is too uneven, a new sleeve is in order.

I have found that Ray A Racing does the best job at repinches and they are cheap. His tooling is first class all the way.

j_blaze

right, the metal to metal pinch where it actually sticks at the top is gone but it has great compression. if i turn it over slow there is no air leaking between the piston and sleeve so i think it wore even or maybe just broke in all the way that day. it was about 1000cc in th ebreak-in and 3 tanks before the filter fell off, then another 4 tanks that day. i'm gonna open it up and look inside and look for the vertical scratches on the piston or sleeve. wish me luck.