Now for the fun part… If you are installing a CH Ignition system with the CTC and are satisfied with the way your engine currently runs at
full throttle, you will just need to lock your timing plate at the full throttle position.
The easiest way to lock the timing plate is to drill (#36 drill) into the side of the plate and tap for a 6/32 set screw. It is better to pull off the prop hub and timing plate to do this, but you don’t have to. Just drill straight in until the drill bit touches the aluminum timing plate bushing. Now run in a bottoming tap in until it stops.
Be careful and do not strip the threads. Now you tighten the set screw and material at the bottom of the hole will lock the timing plate.
If you would want to go back to the throttle coupled system you will have to remove the timing plate and clean things up as the timing plate will probably bind up even when you loosen the screw. You can use a bolt in place of a set screw. If you do not have a tap you can drill a hole and use a sheet metal screw. Just screw it in and lock the plate.
If your engine is set-up with a TCSA mechanical system or you need to set the timing for your CTC equipped engine just follow these steps to set timing.
To install the CTC module, just unplug the pulse switch and plug the CTC between the pulse switch and the ignition box. The Dean’s plugs are correct for a CH Ignition that is all there is to installing the CTC module.
If you have a CH Ignition module with the CTC built-in, just plug it in the same way you would an ignition for a TCSA equipped engine.
The CTC module or the complete ignition module can be wrapped in foam and tied down.
For an engine using a TCSA set the timing to 28-32 degree Before Top Dead Center (BTDC) at full throttle and 2-8 degree BTDC at idle. This is approximately 26 degrees of total movement. To adjust the amount of movement, move the push rod in or out on the bell crank. To adjust the timing, change the length of the pushrod.
For an engine using a CTC equipped ignition set the timing at 28-32 degrees BTDC.
Most of the Sachs engine builders have settled on 30 degrees BTDC.
Ask us about other engine recommendations. The setting depends somewhat on fuel, altitude and outside temp.
The only way to set timing accurately is with a degree wheel.
Buy a 6 inch protractor and a paper clamp at your local discount store. Drill the protractor for your prop shaft then cut out and glue the degree wheel to the protractor.
You can also use a piece of lite-ply or whatever you have around the shop.
Attach a pointer to the clamp. Now you have a timing kit.
Mount the degree wheel to your engine crank shaft. Now all you have to do is find your engine’s Top Dead Center (TDC).
You can do this with a piston stop or a dowel stuck down in the spark plug hole.
Here is another way we have found TDC for many years. Leave the spark plug in and bring the engine up on compression, let the compression bleed off, on some engines you may have to loosen the spark plug a little. You will notice you have about thirty degrees of free travel as the engine toggles back and forth past TDC right in the center of this free travel is T.D.C. With the timing pointer clamped onto to a cylinder head, set the degree wheel so that the free travel at TDC is equal on both sides of zero on the timing plate.
We have found the average engine to have about 20 to 30 degrees of free travel, if there is more than this check your engine. Do this several time to make sure your pointer is on the zero mark when the engine is exactly on TDC.
Keep in mind the pointer and zero degrees do not have to be set at the top of the engine, this is only a reference.
Making sure you do not disturbed you timing pointer, put a spark plug in the plug cap, ground the plug, hook up the ignition and turn it on. Turn the engine over and make sure you have a spark at the plug. Turn the engine slowly and see when the ignition is firing. Set the correct timing by moving the timing plate.
DO NOT RUN THE ENGINE WITH THE DEGREE WHEEL INSTALLED.
Now set up and start your engine. Observe all Warnings and Safety Precautions and use a helper to restrain your airplane.
We should always wear a heavy glove when starting model engines.
Keep in mind any engine with the right (or wrong conditions) can hurt you.
Let your engine warm up and bring it up to full throttle and hold this setting for at least thirty seconds. You may have to set your carb a little richer on the low needle to get the correct throttle response. Now tach your engine at full throttle. Record this figure. If your R.P.M. is O.K Leave as is and go fly.
When you have your engine set where you want it check the timing with a degree wheel and record this for future reference.
If you want, we will set up your engine with the CTC and test run for best performance for $40.00 service charge plus handling. This is labor only and does not include any ignition or engine parts. If you send your engine, send the ignition system, battery pack and switch.