Latest and greatest timing and deck height?

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vonderhey
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Re: Latest and greatest timing and deck height?

Post by vonderhey »

Hmmmm. I wonder if port alignment could affect the performance of the engine as much as the timing change does. Just maybe having the ports aligned as good as they can get along with the fit & seal location in its ultimate location could be a good formula for creating consistent and fast engines. Hint... Von Der Hey.
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Dave N
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Re: Latest and greatest timing and deck height?

Post by Dave N »

Lee,

I always wondered why the sleeves were not pinned or notched in some way to assure the sleeve doesn't twist while tighening the head down. I suppose it would be pretty easy to do some tests with the port perfectly centered, or off slightly forward or back to see if there are differences..
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vonderhey
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Re: Latest and greatest timing and deck height?

Post by vonderhey »

It's the height of the sleeve ports in relationship with the ports on the case that need to be properly aligned. If you raise the sleeve to .203 it doesn't do much good if you can't raise the exhaust manifold port in the case. Likewise with the intake and transfer ports. This sounds simple but there is quite a bit of back and forth measuring and adjusting because of the fit to seal relationship needing to be at the right location. This might be why some engines run very good at .191 and some run good at .196. Having a sized selection of pistons on hand is a must. Von Der Hey.
Mike Del Ponte
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Re: Latest and greatest timing and deck height?

Post by Mike Del Ponte »

KURT, KURT, KURT
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Re: Latest and greatest timing and deck height?

Post by KRProton »

vonderhey wrote:It's the height of the sleeve ports in relationship with the ports on the case that need to be properly aligned. If you raise the sleeve to .203 it doesn't do much good if you can't raise the exhaust manifold port in the case. Likewise with the intake and transfer ports. This sounds simple but there is quite a bit of back and forth measuring and adjusting because of the fit to seal relationship needing to be at the right location. This might be why some engines run very good at .191 and some run good at .196. Having a sized selection of pistons on hand is a must. Von Der Hey.
Are you saying Lee that the objective isn't to tinker with the timing, but to optimize the timing by aligning the ports in the sleeve with the ports in the case?

Then, once you've achieved that, you need a piston to match so it has the proper "pinch" at the location of the sleeve, yes?

Thanks.

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

Post by vonderhey »

Yes, this is what works for me.
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Re: Latest and greatest timing and deck height?

Post by rocket »

vonderhey wrote:Hmmmm. I wonder if port alignment could affect the performance of the engine as much as the timing change does. Just maybe having the ports aligned as good as they can get along with the fit & seal location in its ultimate location could be a good formula for creating consistent and fast engines. Hint... Von Der Hey.
so, ive looked at this from all angles now. theres about a mm of travel for the cylinder from head bolt center l to r without boring the holes in the cylinder or trimming off the threads of the head bolts.. things that make you say hmmm. is it a measurable change? im sure. even the mm of travel you could see better alignment. cool tip.
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rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

At the classic, the blue too sweet is dead... the motor that dominated this thread, cracked case, broken rod, used liner, piston, refurbished diehard is going back on the bench for life 4 of 9.Image
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Kurt Bozarth
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Re: Latest and greatest timing and deck height?

Post by Kurt Bozarth »

Somewhat ironic that I was flying with Rocket when it went in.

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rocket
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Re: Latest and greatest timing and deck height?

Post by rocket »

Kurt Bozarth wrote:Somewhat ironic that I was flying with Rocket when it went in.

Kurt
Wow, yes it is. We have come full circle. Even more ironic that I'm reading this and your eating on the other side of the restaurant. Image
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Re: Latest and greatest timing and deck height?

Post by DHULEN »

It was hauling ass.
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Re: Latest and greatest timing and deck height?

Post by KRProton »

I’m just beginning to understand how to needle a Q40 engine at the line for optiumum performance during the race. My first Q40 race in Wichita (Too Sweet/Nelson engine) Duane Hulen and Mike Deneve did the needlign and changed my diaper for me. But now I’m a big boy, so I needled my own engines at the Q40 classic (under the tutelage of my caller Trey Whitte).

Let me just throw this out there and see what comes back…

Before the racing on Sunday, Trey suggested we go to the airplane stands behind the pits and find peak rpm on our engines (Nelsons that day). Kurt Bozarth looked to be doing the same, so I peaked over his shoulder to see 25,300rpm on his tach! (Kurt, I hope you don’t mind me discolsing this information – better to ask forgiveness than to ask permission.)

Zoiks! I’ve never had my Nelson up that high. But sure enough, I got exactly the same reading on my engine – 25,300rpm. Cool!

So what am I to do with that? The figures floating around the pits are to set your engine on the line 1,000 – 1,200rpm below peak depending upon who you talk to.

So, is this procedure of determining peak rpm in the pits before the race to be used as a base for setting the on the line? Then, I would get to the line, set my engine to about 24,300, launch and race, then read the plug and go from there?

Or, is that peak rpm on the stand only confirmation that your engine is where you want it to be and you re peak it on the line and back off the aforementioned 1,000 – 1,200rpm from there?

Or, either is okay depending on your preference?

I understand conditions may change as the day progresses, so the method of finding peak on the line (then backing it off) may be preferred. My problem with that is, right now I’m too tentative to find peak before the clock runs out. Maybe as I practice that I’ll become more efficient.

I know, I know. Can-of-worms here. :o

Tim
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Re: Latest and greatest timing and deck height?

Post by KRProton »

delateurj wrote:I tend to not peak on the line, I am more of set based on last needle and lean out a little if plug looks I can and not sure what it peaked at last time I bench run.....so can't really say what peak on the ground.

That initial peak on startup is not me peaking. This engine has a tendency to want to jump on the pipe hard right at the start even a half or 3/4 of needle open from my set point. I use thumb partially over venturi to quickly get it a little rich until it warms up and then position set, so bottom line, wouldn't read much into anything before launch.

I am using the Spektrum backplate sensor which is a hall effect sensor that detects crank pin. Zap a dap goo'd into the backplate.
In regard to my previous post/question, this is more along the lines of my preference for the time being. "Position" set the needle (where it was last flight) plus or minus a little depending upon what the plug looked like last flight. Mike Helsel also mentioned this to me as an option (when consulting him about my Jett engine).

Tim
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Re: Latest and greatest timing and deck height?

Post by Kurt Bozarth »

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
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splatt
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Re: Latest and greatest timing and deck height?

Post by splatt »

Hello all,

Taking all the wisdom from Mr. Browns words, I present something.. What I want for myself, are alternate ways to choke an engine other than asking someone to stick their finger in harms way to choke the intake. Is there a butt plug, uh an exhaust outlet method that could be used to keep the engine cool until launch?

Problem: The jump of RPM when starting is the result of no tank pressure at start up. It's lean from the get go making the engine get hot too early, masking the observation of a rich or lean condition

Goal: Having a pre-set needle setting,then being able to choke the engine after start-up until a couple seconds before the flag, maintaining a true needle setting for flight.

Avoid: starting and let it run hard on the pipe for the 45 seconds, allowing the engine to heat up. The thought is that once the engine is overheated it will not cool down on its own when it time to launch.

Optional: To test where your needle setting is compared to this method, after you have flown while needling and letting the motor heat up, on your next flight, leave the needle in the same position, start it choked, keep it choked for 30 or 40 seconds pull your finger off the venturi and push it. It will fly rich all 10 laps.

To find the right needle setting for this type of start. After you have done the type of flight mentioned above, on your next start, with the needle the same, choke it, let it run 30 or 40 seconds to simulate a heat. When you pull your finger off it should be running rich. Don’t fly it yet.

Turn the needle in until it hits the pipe and shut it off. After it cools fly it again. Go through the start sequence again. This time when you pull your finger off, after 30, 40 seconds, it should hit the pipe hard. It’s important that only a couple seconds are left on the clock before you pull your finger off and push. Don't let it sit there and run. Now your first lap is on the pipe and running. The engine never gets a chance to heat up and if everything is good it should run all 10 laps hard.

I need to practice what I preach here and learn what that" hard "RPM is. Now onto the magic spot in a liner. Wha?
Last edited by splatt on Sun Oct 29, 2017 3:21 pm, edited 2 times in total.
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