That would be as not set dead on 28 degrees right????

Ok lets say just for argument sake that it is set spot on 28 degrees just like its supposed to be. At that point wouldnt you look at the carb????

thanks for the info Ralph

The carb is a simple adjustment so go there first. But if it doesn't help the HS miss, the timing COULD be a problem, also weak ignition, bad spark plug, weak battery, bad switch and so on.

Ive changed the plug and gaped it at 25. The battery has a full charge Iam missing something and cant figure it out. Let see if i am doing this right. I start with the piston set at top dead center and set the degree wheel to read 0 and rotate the engine ccw to read 28 degrees and lock it down if that is right then i did it right right?

just a dumb question but does the enging cylinderhead have to be up when you set the timming I thinkI set the timming with the enging inverted michael

TDC is where the pistion has traveled as far as it can go toward the spark plug. The position of the engine has nothing to do with TDC.
Find TDC, set the degree wheel to 0. Hook up the ignition, turn on the battery switch. Rotate the engine CCW until the ignition fires. When it sparks, check the degree wheel and see what it reads. Adjust the timing until it fires at the desired timing when your rotating the engine CCW. DO NOT ROCK THE ENGINE BACK AND FORTH TO SET THE TIMING.

how are you finding tdc. i really like the method avi8tor posted but havent had a chance to try it yet. you must be at true tdc to be accurate.

I let the compression of the engine find top dead center for me, Turn the piston all the way to the top, Install the wheel and rotate back and forth real lightly, you will see that most engine have about 10-12 deg of lose play, Center of that lose play is top dead center.

Milton

And the results is yet another pilot who has no idea where his timming is actually set but thinks its set at 28 degrees and cant understand why it runs so poorly or has to adjust the timming to the mythalogical sweet spot which is where it probably would have come out if the degree wheel was properly set up to begin with..

I dont know why this is so hard to understand.

I have been converting and selling gas engines for close to eight years and the method I posted is about as accurate as you can get, If dead center of the lose play with the piston on top of compression stroke is not top dead center then what is it.

Milton


Words removed by moderator

Champ RN12YC. $3 at your auto store. Get one clamp in a vice, wear saftey glasses, get big hammer use a punch and knock out the guts.
Instant piston stop for finding TDC.

Yep, that would work Terry.  </p>

AV8TOR</p>

</p>

Ok maybee i dont know it all but what i do know that as a holder of a FAA Airframe and Power Plant licence (for twice as long as you been converting engines) is how to find true TDC. I must find true tdc or people may die! are you gona fly on an aircraft where the mechanics eyeballs the dead spot (which from what your describing is what you do) in the slop of whatyou determines to be tdc or are you gona fly on the plane that the mechanic had a sure method to determine true tdc.

So ok lets see why your method is inacurate. first we must see how much movement you can detect with your eyeball. how much can you detect? .001 .0001 .01?????? is your eyball calibrated. do you realize that 1 degree movement close to tdc in the wheel can be assmall as .001" again can you see that???? how do i know this? cause i checked my degree wheel against a dial indicator set up on the piston. Oh by the way on a ryobi engine you will see if you use a dial indicator that there is actually only a 4 degree dead spot. meaning that the time theneedle stops to the point to where theneedle moves again is only 4 degrees. I think this will be the same on most any engine of this size as the strokes are all so similar. Your saying10-12degreedead spot by eyeballing it. can you see the inacracy here??? so knowing this with confirmed by dial indicator and compared to your callibrated eyeball data I can tell you your eye is off by 6-8 degrees.

I dont care how smart or how good you think you are you are in no way gona know just where the dead spot starts or stops without the aid of a measuring device! it is absolutly imposible for you to eyeball this accuratly. most dial indiactor measure to one thousands of an inch and i can garuntee you you cannot see that much movement and know how much it was accuratly.

Ok so now to prove that i dont know eveything i always use a dial indiacator method. why? because that is the FAA approved way. that was the only method i know and i will not again describe it here as it has been described by me on a few threads already. however it was brought to my attention by avi8tor77 that if you use a piston stop. this can be something as simple as a spark plug with the guts smashed out and a rod jb welded or epoxied in so the piston will have a POSITVE stop. positive means that every time the piston comes to the stop it will be at the same degrees on the wheel every time. ok so roll engine one way till it is up agains the stop. roll the engine the other way till it is up agains the stop. place tdc or zero in the very middle of the two and you will have true tdc. this is a garunteed method as the piston stop isABSOLUTE and far more accruate than your calibrated eyeball. i cannot use this method for an aircraft as this is not an FAA approved method and besides that it is terrible to rotate an engine backwards to its normal rotation. not so much for the engine as the accesories like alternator brushes that are worn to one direction!!! so i will continue with the dial indicator for aircraft and I will now use a piston stop for my rc engines.

So the fact that you have been converting engines and selling them for 8 years DOESNOTimpress me. In fact it scares me that you have been shipping engines out for eight years not knowing where the timming was set at and claiming that you did. really makes me wonder about the quality of your conversions????? dont think im gona buy one anytime soon. its ok though i went to the parts store the other day and the stupid parts guy didnt know what a matched set of belts meant so your not alone in the ignorant catagory.

again i just dont understand why this is so freaking hard to understand. this subject has been discussed to death and the methods for finding true tdc have been posted many many times and yet there is always someone (saying someone and refraining from what i really want to say) that will post (well i just eyeball tdc and take the middle of that)

Ya know i just want to add that it really does suck that I have to be the one looked upon as anA-hole just because im the only one that has the cahoneys to come out and say that your method is wrong!

I dont want to be an a-hole. I just want to be able post the right info and be able to correct others and be corrected myself without being looked on as an a-hole. If the persuit of the right and correct way makes me one then i guess i will just have to be an a-hole. but i will be an a-hole with the right info.

i dare you to set your spark up with your method. move your degree wheel then re zero it and see if the spark is at the same setting on the wheel. if you can do this three times and get it dead on same three times your either lucky or your a liar.

your method is wrong!!!!!!</p>

Ok guys I dont have A dial indicator nor the means to set one up the best I can do is use a dowel and move the piston up to the top put my degree wheel on and rotate it back and forth and see how much it moves in both direction before the piston moves and devide by two so lets say the it moves 4degrees ccw before the piston moves and rotate it backto 0 and rotate it cw say4 degrees before the piston moves this is where I thing I am messing up should I add or subtract 4 degrees to 28 derees michael</p>

TDC
Piston stop. setup degree wheel and pointer. Install P.S .turn engine until the piston hits the stop, record number of degrees. Turn engine other way until the piston hits the stop. record number. Add numbers, divide by 2. With the piston against the stop, fudge the degree wheel until the magic number is under the pointer. To validate your math turn the engine the other way until it hits the stop. The degrees should be the same. Of course one will be BTDC and the other will be ATDC
Example 15 deg BTDC and 35 deg ATDC  added = 50 degrees, divide by 2 = 25 degrees. Set the degree wheel so that the pointer reads 25 degrees BTDC &amp; ATDC when the piston is against the stop.
Using a piston stop is more accurate than a dial indicator simply because it will load the bearings and remove ALL the slack from them.
On a simple single its super easy to use. . On a multi cylinder with heads and accessories on its a major PIA as combat pilot explained
 A dowel can shift, get a long reach spark plug and make a piston stop.
WORD OF WARNING[X(] IF YOU FINALLGET IT RIGHT, DONT tell anybody in your club. If you brag about being able to time an engine you will endup timing everybody's engine anytime it burps. Make every body think its Rocket Science, even though its so simple after a few times.

thanks michael

that and as I found out, if you get cocky and brag at all, something on your plane will have a conversation with mr murphy...

OKI have it now thanks TKG I now have it set at 28 degrees you explained it to where I understood it and thanks to all of you guys that also helped I took what all you all were saying and put it together to were it made sence to me now the engine ideles real low cant kill it wit the trim so I guess I forgot to solder the hole on the butterfly eighter I got lucky or i did it right either way its running good it will hand start in one or two flips of the propwhen I rechecked the the timming it was way off like 40 degrees havent tacked it yet but when I go from ldel to full throtle there is no lag time it is there again thanks to you all you guysyou are the best on RCU thanks michael

Michael did you finally use and understand the piston stop method? If you did can you now see why using a dowl to try and feel the piston dead spot would not work real accurate. Its not that hard to make a piston stop. Its so simple once you understand it.

Sounds like you got it right this time if your engine is running that good. Isnt it nice to know your dead on where it should be and you dont have to guess and hand tune it?


Like I say this subject has been discussed to death on here. I just dont understand why it is so hard to understand when the process is so simple.

I think if I can afford to get another ignition box and i can find someone to video and edit me, I will make a video of this process and place it on youtube. It really seems there needs to be an instructional video of this.

Terry i think your right when you say its more accurate then a dial indicator. I think the method describe above is the best way ive heard it described. I really have to thank avi8tor for turning me on to the piston stop. Its so freaking simple lol.

no I dint use a piston stop I tried to look at that link byt it would open so i used a dowel and used what you all have said set the tinning and rotated the crank 3 times and it was firing at 28 degrees thanks again michael ps cant wait to to the vedio on how to set it up michael

Yea I really would like to do a video on it. I think i know who can help me put it all together but i need a new ignition box.</p>

Well I see you edited your post and took out where I was a idiot, stupid and if I said I could do it three times and get the same reading I was a lair, Will do another post later to see if that is all true.

Milton

<p style="MARGIN: 0in 0in 0pt" class="MsoNormal"><span style="FONT-SIZE: 9pt; FONT-FAMILY: "Arial","sans-serif"">10-12 On </span><span style="FONT-SIZE: 10pt; FONT-FAMILY: "Verdana","sans-serif"; mso-bidi-font-family: Arial">compression </span><span style="FONT-SIZE: 9pt; FONT-FAMILY: "Arial","sans-serif"">is right.  Not 4.  what you are doing is bring the piston up all the way.  Let the compression leak off.  then move it back and forth.  You will see that it will be about 10 to 12.  divide in 1/2 and that is TDC, set timing.  run engine see what you get with rpm.  Move timing to see if you get more or less.  Set it for the best running that you like and your done.   it is not that hard and no one will die with a off timing RC plane.

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I was reading same thread....seems like no timing wheel is needed or piston stop. Just get engine running and advance timing in small amounts untill top RPM is reached. My next engine will have a moveable pick-up to advanceand retard spark a few degrees. Some new engines come that way. I do not see what all the fuss is about. Go cool your brains a bit. Capt,n