BadAzzMaxx

Here is a link showing how to time a engine for RCexl without using a degree wheel.

http://www.rcextremepower.net/ignition_timing.html

Also here there are some neat new products coming from RCexl in 2012.

Milton

bcchi

Boy that Ralph is trickey.Plus being grumpy.This is much eaiser then measure the paper thing.Of course I use the TLAR method or eyeball timing.
BC Used to be BCCHI.
Youll never no how little I really care.
Bill

Antique

My Feedback: (4)

OOPS 3.14 not 3.4

BadAzzMaxx

oooops, corrected.

Thanks

Milton

soarrich

My Feedback: (98)

The paper thing was invented because some people are just adverse to math of any kind.

Whistling Death

Or for people who don't own a dial caliper.

Antique

My Feedback: (4)

Dial caliper is a very handy thing to have, cost around $10 from Harbor freight or Ebay..Sometimes free with an order from Boca Bearing....

BadAzzMaxx

If you do not have calipers, You can do it with a measuring tape and a couple blocks of square wood on a flat surface.

But the calipers are so cheap anyone in the hobby should have one.

Milton

Whistling Death

I own two Brown and Sharpe's but you are right, at that price, anyone that is in this hobby have a set.

BadAzzMaxx

Yep, Pay $15.00 for a servo arm, $10 bucks for a good tool sounds cheap. LOL

Milton

Whistling Death

Ah, but it isn't an "RC Caliper". If that same caliper was rebranded and sold by Dubro or Hobbico it would cost you 3-4 times as much. [>:]

a1pcfixer

My Feedback: (7)

FleaBay has 'em........

http://compare.ebay.com/like/3902468...=sbar&_lwgsi=y

HunkaJunk

I have done something similar on 2 strokes where I didn't have access to the output shaft. I found TDC and BDC, and measured the distance of each with a depth gauge (measured through the spark plug hole). A little mathematics gave me a distance for the desired degree.

w8ye

My Feedback: (16)

This finding of TDC and BDC directly does not work because of the sweep of the connecting rod big end.

It must be done as Milton explains it.

av8tor1977

My Feedback: (6)

YEP. The positive stop method as shown is the only sure way to find true TDC. That's the way it is done even in super high dollar auto racing.

AV8TOR

Antique

My Feedback: (4)

Or in the case of a straight up spark plug, an old spark plug with the porcelain bored out to fit a cheapie 0-1 depth dial indicator...

MetallicaJunkie

i find TDC the way i learned in a video on you tube..... where can i get a cheapie dept dial indicator?

captinjohn

Now we are talking something good! That gets my vote....Capt,n

blikseme300

My Feedback: (118)

You can get one for about $20 at Rex Supply, 1313 West Ferguson Street Pharr, TX 78577 - (956) 781-7761

They are a great local source for machine tool things.

Bliksem

w8ye

My Feedback: (16)

The only way to accurately find top dead center is to accurately stop the piston at the half way point in both directions and then select a degree point half way in between these two.

This is the method Milton talks of.

Directly measuring BDC or TDC with a dial indicator, it would be more accurate to feel for TDC with the prop and then make the timing look about right like Bill does?

captinjohn

It is not so much the way or tools you use to find top dead center. It is how accurate the person is inusing the tools in the right manner. Capt,n

MetallicaJunkie

thanks Carl

av8tor1977

My Feedback: (6)

Ralph, you know very well that a dial indicator won't give you true TDC unless you use it to measure a specific distance on either side of TDC and then split the difference. That is the only way to eliminate the dwell time of the piston at TDC as the crank goes across its travel. I know, it is "splitting hairs" a bit as far as timing these little airplane engines, but correct is correct right??

AV8TOR

captinjohn

I am sure Ralpf (the Antique one) knows how to use a dial indicator and any machine tool related to RC. It is simple. Say the stroke of the engine was 1.000 inch. Just lower the tip of the indicator .500 and that will be mid travel of the piston. If a guy cannot figure out the rest.....forget buying a indicator. Go play some pocket pool!!!! Capt,n

Antique

My Feedback: (4)

Actually guys, I don't use anything..been doing this long enough to know where TDC is by feel...The middle of the dead spot when the piston is alll the way at the top...A few degrees either way makes absolutely NO difference in the way the engine runs....ONLY engine I ever found to make a difference was a 289cc race engine...Ran just as well at 22 BTDC as it did at 28....Tming is much ado about nothing, just like oil ratios and brands...Use what works for you....