Latest and greatest timing and deck height?

Pylon Racing General Interest --
sahartman21
Super Contributor
Posts: 597
Joined: Thu Jan 10, 2008 8:52 pm
Location: Fritch, TX 79036

Re: Latest and greatest timing and deck height?

Post by sahartman21 »

Obviously your wife is much more supportive to this hobby than most of our wives.

Great story!
Scott Hartman
Fritch, TX 79036
KRProton
Super Contributor
Posts: 895
Joined: Mon Sep 15, 2014 3:11 pm

Re: Latest and greatest timing and deck height?

Post by KRProton »

FYI, I swapped between my Sweet 1 (with Jett) and Too Sweet (with Nelson) at the Champ race last weekend. I didn’t seem to have the speed and my plugs kept coming out too dark – not destroyed, but definitely more heat than I wanted. Theorizing that the good (dense, cool) air was the cause of over-compression, I raised the head on both engines and used the lightest props I had. Seemed to help, but the plug was still too hot. The Nelson ended up at .190/.021 if memory serves – pretty close to standard if there is such a thing. On Sunday the air seemed to be getting warmer – same as I’m accustomed to in the Midwest in the summer. Then, my engines started going better. After a practice run during the lunch break on Sunday the plug in my Nelson came out perfect – first time all weekend!!! Unfortunately, I killed my last opportunity to test it in a race due to my error in shorting my plug clip how I had it connected to the engine and didn’t get it started. :oops:

Anyway, in retrospect, I should have simply launched at a lower rpm by setting the needle richer. There were plenty of clues for me to do so; For one, listen to what your glow plug is telling you! Two, another experienced racer told me what rpm they were launching at which was much lower than I ever considered. That should have tipped me off as well. Probably would have had the correct fuel/air mixture and I guess more speed! Even though I’m behind the curve, hopefully my understanding is correct and I’m on the right track.

Hey, live and learn!

Tim
vonderhey
Super Contributor
Posts: 241
Joined: Mon Apr 13, 2015 12:22 pm

Re: Latest and greatest timing and deck height?

Post by vonderhey »

I would like to correct many of you.
“ Motors have windings “
splatt
Super Contributor
Posts: 114
Joined: Mon Aug 26, 2002 4:56 pm

Re: Latest and greatest timing and deck height?

Post by splatt »

To put another spin on it, Real motors have windings. Get it, spin?

Now that you're thinking clearly, lets say we go back to the beginning and try to apply what we learned thus far. My angle is to make what I already have work as best as possible, without having a bin of pistons or piston return springs to pick from.
rocket wrote:The higher timed guys, 7 under 11, 12, 13 over. The factory setup is 3 to 5 under 13 over. The lower timed guys nothing under 15, 16 over. The higher timed guys favor the 5 prop. Lower timed guys 6 and 7 prop. You wanna play with hotter plugs... 10 under 15 to 17 over. 5 prop. The difference in the no shim under setup and 6 thou under is 2 degrees in exhaust timing. You should measure the stroke. The norm is 188-9 tdc but some cranks have been measured with more.
We have higher timed, factory, and the lower timed crowd. Help me identify this. They tend not to wear colors or have stickers on their flight boxes

I am measuring timing with a 360 degree wheel. ( But others do a hard mechanical method with some kind of decimal number? ) Stop me here if I am wrong

I measure the total degrees of exhaust duration opening using a LED light to detect when the port is just closed. Using this method, I am taking all the variables of manufacturing and seeing what that bunch of assembled parts is offering me, as an engine assembly. Right so far ?

So , what is high, factory , low timing? is it best to talk in degrees of timing or a mechincal measurement I have yet to learn.

I have an unused factory engine that measures 202 degrees of duration
I read Henry designed it for 200 degrees of exhaust timing
Mr. B make his junk go at 198,,,, ?? yeah junk, I said it . is that low ?

Once we agree on that , we can move onto head spacing, ?
vonderhey
Super Contributor
Posts: 241
Joined: Mon Apr 13, 2015 12:22 pm

Re: Latest and greatest timing and deck height?

Post by vonderhey »

There is no magic set-up. There are very different combinations that can produce the same results. Example: A .191 & .020 engine running a higher pitch propeller could go sub-minute. A .198 & .024 engine could also go sub-minute. The pitch in any propeller is measured in inches which means for every 360 degree rotation the propeller would move forward that many inches. This is how the propeller is measured. Now of course there is no such thing as a 100% efficient propeller which means that due to slippage the propeller or aircraft won’t move forward as far the measured pitch on the propeller. All that being said I will explain my point. A lower pitch propeller with higher timing turning more rpm can have the same efficiency as a higher pitch propeller turning at a lower rpm which explains the different successful set-ups.
Von Der Hey.
rocket
Super Contributor
Posts: 901
Joined: Sun Mar 01, 2009 1:57 pm

Re: Latest and greatest timing and deck height?

Post by rocket »

Was out today running at 200° of exhaust timing. I.E. I started at my happy number of 197 and added .009 under. I'll be dammed, there is life above 197°. After a chat with Mr Von der hey about setups running deep fitting pistons. I set this one with the piston biting down at .325. Why so deep after i cursed this tight fitting piston setup. Well, with the piston fitted deeper, it starts to seal sooner and compresses more air/fuel. Plus with the liner jacked I needed a tighter fit to offset the height. Lee also mentioned the head clearance will need to raised due to more air/fuel being compressed. Well, the plug told the tale, I started at .020 and have had to add a few thou to keep the plug from looking Frazer on a 6 pack. The air today at Markham was cool and dry which contributed to the higher head.
And I said, here am I send me.
airraptor
Super Contributor
Posts: 18
Joined: Fri Apr 29, 2016 10:17 pm

Re: Latest and greatest timing and deck height?

Post by airraptor »

On my engine at Whittier last week I was running .197 and .023. It ran well and piped up all day no changes at all. It had a best of 29,370 on the race course with a 7.6 prop. Others were running .193/194 and .019-.020 and were fast and sub minute times. If you guys had seen my top end you would yell at me. Its all peppered from a bad run long ago. I never cleaned up but is running strong. I better change the rod out before Phoenix.
Kurt Bozarth
Super Contributor
Posts: 250
Joined: Sat Jan 25, 2003 12:36 pm
Location: Aurora, Colorado

Re: Latest and greatest timing and deck height?

Post by Kurt Bozarth »

Question #1) So if an engine is running mediocre (not hitting the pipe very hard) at 197/23, what do you start moving first, the sleeve height or the head height? Same question with a lower timed setting.

Question #2) I have made a list of all of the settings mentioned throughout this thread...almost every possible combination has been mentioned. Are most addressing the approx. 0.003 slop?

Thank you,
Jennifer
(Kurt's wife)
Kurt Bozarth
kbozarth01@gmail.com
Kurt Bozarth
Super Contributor
Posts: 250
Joined: Sat Jan 25, 2003 12:36 pm
Location: Aurora, Colorado

Re: Latest and greatest timing and deck height?

Post by Kurt Bozarth »

deleted
Kurt Bozarth
kbozarth01@gmail.com
splatt
Super Contributor
Posts: 114
Joined: Mon Aug 26, 2002 4:56 pm

Re: Latest and greatest timing and deck height?

Post by splatt »

aw come on , put it back. I was digging it. There's nothing else to do this time of year :P I wonder what a 7.6 prop would have done being timed under 198 degrees of timing .

what did the plug look like ? Did it offer any clean jump onto the pipe ? Try doing the choked start thing , choke it for 20 seconds and push it off or at least see what RPM it does then after choking it that time, leaving the needle where it was from the previous flight.
vonderhey
Super Contributor
Posts: 241
Joined: Mon Apr 13, 2015 12:22 pm

Re: Latest and greatest timing and deck height?

Post by vonderhey »

Hmmmmm...... The pipe design can be a double edged sword. It develops quite a bit of horsepower at specific rpms. It also becomes a governor as well which means that there is a peak rpm that the pipe will allow. Do take note if you get caught up in running engines with real high timing you run into a problem that doesn’t usually come to mind. If the timing is high to the point where the pipe is governing the rpms then it is almost impossible to determine which engine is better than another engine.
Von Der Hey.
GaryS
Super Contributor
Posts: 348
Joined: Tue May 14, 2002 1:58 pm
Location: Worldwide

Re: Latest and greatest timing and deck height?

Post by GaryS »

vonderhey wrote:Hmmmmm...... The pipe design can be a double edged sword. It develops quite a bit of horsepower at specific rpms. It also becomes a governor as well which means that there is a peak rpm that the pipe will allow. Do take note if you get caught up in running engines with real high timing you run into a problem that doesn’t usually come to mind. If the timing is high to the point where the pipe is governing the rpms then it is almost impossible to determine which engine is better than another engine.
Von Der Hey.

No wonder I can never figure out which of my sub 59 second engines is best! :D
GS
rocket
Super Contributor
Posts: 901
Joined: Sun Mar 01, 2009 1:57 pm

Re: Latest and greatest timing and deck height?

Post by rocket »

Another coil tip. When you have a tail heavy CG issue and you need to mount the battery up in the nose. Getting velcro up in there, getting a battery up in there is a pain in the ass. Here's a cool tip. Mount balsa wood on to your gas tank that you will use as a stopper for the tank anyway. some thin CA on the basla so the velcro will stick. Velcro on the battery and Slide the whole thing up in there one shot, boom, done.
Attachments
20180516_153718.jpg
20180516_153711.jpg
And I said, here am I send me.
vonderhey
Super Contributor
Posts: 241
Joined: Mon Apr 13, 2015 12:22 pm

Re: Latest and greatest timing and deck height?

Post by vonderhey »

Hey Ray, You should fabricate those and ship them to the pylon world. I'm sure the Post Office won't think it's a bomb. Von Der Hey. :lol:
rocket
Super Contributor
Posts: 901
Joined: Sun Mar 01, 2009 1:57 pm

Re: Latest and greatest timing and deck height?

Post by rocket »

Yeah, they might ask a few questions after x raying these.
And I said, here am I send me.
Post Reply