Oh well! I guess the saying IS true: Ignorance is bliss!

Actualy that is not the complete expression. The complete expression is "'Tis folly to be wise, when ignorance is bliss".

An RC engine can actually be reassembled properly and work perfectly without the necessity of a torque wrench!

After paying what, $80.00/hour, for service at the car dealership, I wonder if you would adopt the same attitude.

Consider the words of a Pop song of many years ago. "Little things mean a lot". You should know Gary, it is sometimes the difference between first place and also ran.

Ed S

[BillO]

Previously, I have found an interesting supplier site with various items for sale including a torque driver.
Go see http://www.darrolcady.com and check out the driver he has for sale and his write up. Find this item near the bottom of his home page.
Here's an exerpt of what Darrol Cady has to say regarding head screw torqing:

"When I check engine set ups for others, I find that most are over tightened. When your head bolts are too tight, it distorts the case and sleeve. The engines do not run as well as they could. I set my head bolts at 11 inch lbs. and it seems to be perfect."

To paraphrase what someone said earlier, it may be why someone might be an "also ran" if you're looking for speed. It may also be the difference of having an engine for a few years versus having it running well for decades. I've got to think that to torque the screws on our expensive engines by hand may get us close to equal from screw to screw, maybe, but at what value? Too tight or not enough? I suppose it's "tight enough" if the fuel doesn't leak from the head (or rear seal) but that trial and error is just not good enough for me. If it is ok for someone else, good for them. I torque with a hand driver at 11 inch lbs, and consider the screws equally tightened within the accuracy of my driver, but have not seen or heard any difference myself versus hand tightening previously. I just feel better about it. Maybe I was lucky with how I used to hand tighten the screws.

A torque driver could be a nice Christmas gift (even a late one) for someone, like ourselves, or get it for your next birthday. Or not, it's up to each of us to decide if we want another gadget.

Merry Christmas to all of you,

This is what we are "Torqueing" about. My apologies.

One has to use some type of wrench to tighten screws, why not one of these? It is adjustable from 0-36 in-lbs, more than adsequate for most of the screw sizes used on even our larger engines.

Notice I wrote "in-lbs" that is what is marked on the wrench. However as stated by DO335 the correct form is "lbs-in" as verified by Machinery's Handbook.

Ed S

[moo]

M3x18, six bolts on an OS160FX

Consider the fact that OS won't give out info like torque or how to extract the wrist pins from four stroke engines. Yet they do sell spare parts.

OS just doesn't want to help.

CALCULATING MAXIMUM MACHINE SCREW TIGHTENING TORQUE VALUES

The most widely used formula for calculating threaded fastener tightening torque is:

T = DKP

Where:

T = Torque (inch pounds and Newton meters; 1Nm = 9 in.Ib.)

D = Nominal thread diameter (expressed in inches; 1 mm = .03937 inches)

K = Nut factor (.22 for zinc electroplating)

P = Pounds of clamping force (75% of yield strength)(Remember, Aluminum, so less is better)

There are various strength levels of metric machine screws and each has a different recommended tightening value. ISO has two predominate machine screw strength levels: Property Class 4.8 (close to SAE 6OM) and Property Class 8.8 (close to SAE 12OM). Property Class 4.8 indicates a minimum tensile strength of 480 mega Pascal (MPa). This is equal to approximately 70,000 pounds per square inch (PSI). Property Class 8.8 indicates a minimum tensile strength of 880 mega Pascal (MPa). This is equal to approximately 127,000 pounds per square inch (PSI).

[moo]

Less than one Nm steel to steel.

[Guest]

Gee there are so many factors just in the way you apply the torque.
Wet (oiled threads)
Dry
and then to yield.

Most have been doing this for years just by feel. My suggestion is to torque them by feel then use the torque wrench to find out where you are then do all of them equally. I think your torque pattern and the increment is more important.

Dennis

[Vulcan1]

I consider Darol Cady a friend as I have raced and had a few brews with him. He is in the fast crowd along with Shadel and others. I consider ED in the same group as you will note by his workmanship and comments. They are all very close to perfectionists and it is the need for speed in competition where it really comes out.
Most guys myself included have been tightening bolts for years without a problem but for myself I prefer to use the torque wrench especially on my good engines. I am an ex h/d mechanic and the size does not matter for engines when putting them together. Uneven tightening will warp parts and if you talk alum. engines(auto) and a mech assembles it without a torque wrench and you drive it a 1000 k's and get a head gasket leak from a warped head then I do not think your vocabulary would be good around my grandaughters. A torque wrench is in the category of would be nice to have but most that are playing with engines find it is mandatory. I have I believe 7 in my tool box from a couple of small 1/4" type to a 3/4" 600lb.ft. In my trade they where required if you wanted to stay employed.
John

[volksman]

if ya want to get down to the nitty gritty. as dennis has stated where the wrench or driver is griped on the handle the fit of the socket or allen head and if oil is used or not affects the torque. the run down torque is the force needed to overcome the friction in the threads if no friction it wont hold the torque. the classes of threads have different run down tolerances etc etc more to it than meets the eye. john must have used very high torque values where the the stretch o the bolt determines the applied torque more things are made leak or just simply ruined from over torque or miss matched values which warp things its close to rocket science if ya want to take it that far

[Lash]

I just wanted an equal value on all the bolts to prevent leaking/warping. The number seems to be 7 or 8 in/lb.
Vulcan, I didn't realize that this would provide an rpm increase like you obtained. Good to know!

[Gary Maker]

Originally Posted by volksman

this one is for gary. ive never used a torque wrench on an rc engine, nor is it necessary. why do you always post perfectionist sarcastic crap. simple information that maybe not every one knows in this post. ed and john posted correct information. as i did.

Now come on my friend, I don't always post perfectionist sarcastic crap. Sometimes it just simple plane ole crap!

Sorry if I was offensive. But opinions were asked for and an opinion was given but was answered with a sarcastic response. I for one appreciated the info DO335 gave and found it informative. I gave my response because I didn't think the response he was given was fair. He gave an opinion only! Why was the type of response given him necessary? I don't believe it was! Anyway, lets get back on topic.

That being said, I have indeed learned something about torque and torque wrenches in this thread and I appreciate the info given. Geez, I may even go out and purchase one of those nice torque tools that Ed has displayed.

Do you mind telling me where you purchased it Ed and the approx value of the tool?