Latest and greatest timing and deck height?

Pylon Racing General Interest --
KRProton
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Re: Latest and greatest timing and deck height?

Post by KRProton »

Kurt Bozarth wrote:Hey Tim,

Here are my only two cents worth:

$0.01: I don't think anyone needles to peak on the line and then backs it off.

$0.02: Motor set-up and airplane (tank height) can dictate how much to be off of peak on the line. Different set-ups unload differently.

Kurt
Thanks Kurt!

Now that's something I can work with...

Yes, peaking on the line, then backing it down doesn't sound right to me either. I was probably misunderstanding something there.

So then, to your point no. 2 (determining how far below peak to launch), you need to know how the engine behaves in your plane and read the plug after a flight to determine where to set it for launch.

And apparently, the procedure of peaking the engine on a test stand on location before the race lets you know the peak rpm at that point in time. Given that, and your prior knowledge of how far below peak to launch, you will know where to launch that day.

Sounds like one of the first things you do before you fly is to peak the engine on the ground to see where peak is then and there.

In my case, my Nelson in my Sweet Vee that Sunday morning peaked at 25,300rpm. I'm running a Jett oval tank as high as it will go, so the plane does not have a tendency to lean as the flight progresses - it seems to remain pretty much consistent through the 10 laps. We were launching it at around 24,300 and even "eeked" it up from there a bit. As the heats progressed the plane seemed fast (after my last race with Danny Coe he said "man, you got some speed!") and the plug looked good, so I'm there - I guess.

Given the above, for practice I might launch about 1000rpm below peak, read the plug and go from there. I can get into shimming later once I have a better understanding of a good launch rpm.

Thanks again.

Tim
airraptor
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Re: Latest and greatest timing and deck height?

Post by airraptor »

I am new to this racing, well new compared to must in here. One thing is almost everyone will help you. This past Phoenix classic was my third time and the biggest thing that has helped my times on the course wasn't the best engine prop or so forth. It was flying the course as best you can. You can take any of these guys like Ray, Lee, Travis, Dan and many others and give them an early polecat with a old SS engine and they will still turn a 61 or 62 on the course.
Like I said I am still learning and with the two planes I fly the Strega and the Dago. Both of these I have the needle one turn open from last run adjusted if needed depending on the plug. Then when race time I prime at 50 seconds, start engine by 42-45 seconds, and once its running I close needle half turn and pull glow igniter. At the 35-30 second mark I tune to peak (clear smoke) then richen until smoke reappears and then continue to rich till a very slight rpm drop. This works for at this time but one day I will work toward the leave needle alone and choke carb idea. But that is down the road for me now its engine starts every time and pipes up for the race. flying the course has improved my times the most.

As far as the engine goes my thoughts are what ever you do stay with the same methods of measuring, shimming and tuning, changing methods will just keep you chasing issues IMO. As far as telemetry goes I have seen up to 29,300 in the air on a 7.6 prop. This was on a sweet V built by Richard so I know the firewall was correct and all. With timing my number one engine liked .008 under the liner and .012 under the head on hot days with low density air. On the colder and high density days it liked .006-.007 under liner and .009-.010 under the head. Now with that I changed out the whole top end on that engine set up with same numbers and didn't run as strong as it did before. So like Ray and Lee said piston fit and liner alignment are important.
All of this is my opinion so good or bad its what works for me so far but in racing you are always learning. Oh one thing I learned with normal sport engines when messing with timing and all with them is if oil was dark it had to much compression or overloaded with prop. Thoughts?
rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

I received my boxes back from Phoenix. Had the opportunity on Sunday to clean up the motor from the blue too sweet which crashed around pylon 3. Basically the old case with the cracks from the broken connecting rods has seen its last match. Rather than bore you with the rebuild I'll just show you a couple cool tips, and the finished product. The first picture is a relief hole for a crack on the web. I think the crash in Phoenix caused the crack to move into a case so it was time for a new case. Image
Also, scribing the date on to your connecting rod is a sure way of knowing exactly how old it is not necessarily how many flights it has unless you log your flights. This was the connecting rod from the crashed too sweet. It's thought that a crash like that where the motor comes to an abrupt stop will cause the connecting rod to fail if you use it again. So better safe than sorry.
Image
New case, conrod, front bearing and she's ready for life number 4 of nine. Image
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KRProton
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Re: Latest and greatest timing and deck height?

Post by KRProton »

I got my stuff back from Phoenix too - came through perfectly intact! :D (Though my wood crate/box needs a little repair.)

Thanks for more tips Ray - and the images - always enjoy looking at Q40 engines! :mrgreen:

Tim
Last edited by KRProton on Mon Mar 06, 2017 3:24 pm, edited 1 time in total.
rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Gorilla grip, glow plugs and last place.

It seems lots of folks enjoy reading the latest and greatest thread. It also has caused yours truly to take on the job of impromptu engine checker. Being the eternal tinkerer I said sure, I'll have a look, it will give me something to do lol. Anywho, after disassembly and a thorough looking at. I thought what I found worthy of a pic n post.
The gorilla grip glow plug install will cause the smaller of the two bowls to deform. Prolly leak and is definitely detrimental to the horsepower.the first two pics are healthy heads with the proper shape in the bowls.ImageImage
You can see in the next two pics of a gorilla gripped glow plug install an the deformed bowls.ImageImage
Just snugem enough where you can spray your favorite cleaner on the head, turn the prop to TDC and check for bubbles. Anything more than that is unnecessary.
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rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Someone was listening.

A transcript from an email thread between mario, Dan and myself.

Hey Ray,
Mario and I were perplexed following our Phoenix racing! We used your technique using the degree wheel and I believe we've found the answer why Mario's engine was a Missile and mine was so cranky when both were setup at .194/18

This is what we found using the degree wheel, let me know if what we found is correct?

My motor was setup at .194/18 using my depth mic setup, degree wheel showed .201° of ex-timing and .184 from the top. (Bare) So with the .010 shims added to get me to .194 that put my ex-timing at 204.5°.

We degree'd Mario's Missile Motor and saw these numbers, .197 Ex-timing and .187 from the top. So putting .006 under the sleeve takes him to .193 with ex-timing at 199°!
So in conclusion my motor had very high ex timing as compared to Mario's with both engines setup at .194/18!

So to get my motor as close to Mario's I'd need to remove all shims to get 201° lowest I can go with his motor shim'd to 199°!
But my ex timing would still be 3° more open than his!
This would explain why it was so tough to keep in the pipe on Sunday!
Is this finding correct!

Thanks Ray!

Dan Thordarson

~~~~~~~~~~~~~~~~~~

Ray,

Thanks for sharing your tips on the forum.
Dan and I are just trying to duplicate good engines' settings as much as they are "duplicable" to our other engines.

We'd really appreciate your input!

Thanks bud!

Mario Salazar

~~~~~~~~~~~~~~~~~

That's exactly right. Setting the motors with a depth micrometer and shims means nothing if your trying to set two motors the same. 200° of exhaust timing is where Henry designed it to run. 200 or less is favored. RR
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KRProton
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Re: Latest and greatest timing and deck height?

Post by KRProton »

Some pages back there was discussion about using a ring on the back of the firewall for securing the engine mount bolts rather than using blind nuts. I didn’t even know it, but the other day I was on the Jett web site and happened across a reinforcing ring made by Jett for his engine mount (and apparently, most other ring-type mounts) – this is ready made for those who use the Jett mounts. The ring is listed at the bottom of the price chart about halfway down the page:

https://www.dubjett.com/accy2015.html

Wish I would have known about this before! :P

Tim
Attachments
Jett mount ring.jpg
Jett ring.jpg
rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Lol, you did. You just read too fast. Mike langolis has them as well. The bolt pattern is the same.
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KRProton
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Re: Latest and greatest timing and deck height?

Post by KRProton »

Don't know how I missed those mount rings Ray. I thought I made some kind of discovery everybody else had missed! :roll:

Tim
rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

I think it's in your too sweet build thread too.
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KRProton
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Re: Latest and greatest timing and deck height?

Post by KRProton »

Well,

I do remember several mentions and an image or two of a ring, but I thought the rings I saw were homemade from aluminum engine mounts with the beams cut off, not the manufactured Jett ring.

Huh.

Tim
splatt
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Re: Latest and greatest timing and deck height?

Post by splatt »

Someone let this thread fall to page two, so much information here. I decided to take little bits and pieces of what I learned here to help me find where my ideas of engine operation play out. And since the weather is crap, its time to bench race

I am going to put a new top end in a small flange and figured I would test my contraption on a known quantity of engine build first to see if I can correctly record what a good engine set up is.

A maximum of 200 degrees and no more of exhaust duration is said to be a target. OK. I have an engine that I want to see before I have a chance to wreck it. Using nothing more than normal household items, items found on my workbench and the power of the Internet. I can check my own exhaust duration and see for myself

Me and my friend attached a motor mount to an old wood assembly stand. Then I googled degree wheel and hit the images link and looked at several images of degree wheels. I decided to use one with 360 degrees marked out because of the goal needed, a total count of degrees.

Once I found one I liked, with MS Windows, I click Start and type snip and open the MS Snipping tool and save an image of it. Save it. Print it. Cut it out, Safety moment. Don't hurt yourself

I used a some thin paneling board and used Contact 77 adhesive to apply it. Cut it out with a scroll saw and then covered it with clear packing tape. Drill a hole. Slap it on. Put the prop on front of it and tighten the nut, just enough to it snug so you can zero out your wheel with your finger tips.

I used a clip on LED light for a music stand and aimed it into the port. I can hold this whole contraption in my lap and leave both hands free to fiddle with. Then I zero out the wheel at the point where the light from the LED just disspeared when looking at the port from the inside, referencing the powerful image below from Mr. R. I used a stack of tiny washers and an allen wrench to fashion my pointer
Capture.JPG
Then its just a matter of spinning the wheel around till the light once again just disappears. Here is what it looks like with no shims under the sleeve. 195.5 -- 196 degrees of duration.
one.jpg
After placing the 2 shims back in, a 003 and 008, the timing comes out to be just a touch short of 200 degrees. Walking away and coming back to look again, I get 195.5 degrees of duration.
Capture2.JPG
I will want to look my other engines as time goes by and will be interested in any comments on duration. When to change, when to leave alone. Humid , dry, ocean or mountain tops.
Last edited by splatt on Sun Apr 30, 2017 9:24 pm, edited 4 times in total.
rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Just a reminder "cause I didn't read where you mentioned this" you need to be looking at the lowest possible angle to get the most accurate reading. Anything more than this diagram your seeing the taper of the piston top. Cool idea on printing your own degree wheel.
Image
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RSmith
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Re: Latest and greatest timing and deck height?

Post by RSmith »

If anyone is looking for a good quality degree wheel, Hank Kauffmann had some made out of FR4 circuit board material (fiberglass sheet) and had the 360 degree scale etched on to the board same as is done with printed circuits. He was selling them in Phoenix for about $10 or $15 I think. Center hole is 5/8" for Q40's and he might have some with a smaller hole for 426 - not sure. Contact Hank if you're interested.

Randy
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rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Image
This thing is too nice to use. If he's selling them, I would get one for your trophy case. Or, if you don't mind using a work of art to measure your motor with then by all means.
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