IHC LA Engine Trouble HELP!!!!

Here is some stuff about the LB.

1st. Check the magneto to see if you are getting fire. If you have it, then, the thing must fire at or just a hair past tdc. If you dont do it this way, when you try to wind it up, you are going to miss an arm.

2d. As you have had the head off, I think your problem is more than likely there.

When you view the front of the cylider looking towards the rear, at the bottom, there is a hole. In that hole there is a slip on square coupling. This coupling hooks to the govenor and carb. If you do not have this connected correctly, it will never run.

The butter fly valve in the carb must be full open while the engine is not running. To make this happen, take the rear access cover off. Get a light and shine up in there. You will see the governor shaft that runs to the front through the block. It will be spring loaded down. Get someone to hold the lever on the shaft with a screw driver in the full opposite direction. As they are holding this, you go to the head, and guide the butterfly shaft onto the linkage and install the head. When the screwdriver is released in the rear, this will allow the valve to go full open up front.

Bolt it up.

If you have proper timing, fire and gasoline, it should run.

If it does not, you might try a shot of ether in the intake. If it hits and runs for a moment, you will then know you have a dirty carb.

Check this out first. If you have further problems, get back with me. at twindsor@aol.com

PS. it took me a full 1/2 day to properly time one of these engines. The magneto should click just as the timing mark hits tdc.

tw

Here's a couple things to check:

First, is the impulse on the magneto working? As you turn the engine over you should be able to hear it click. Take the end cap off the magneto and watch the shaft as you turn the engine. The shaft will stop turning as the piston comes up on compression, then snap through part of a rotation as it opens the points. If the shaft just turns, the impluse is stuck & needs to be cleaned. Weak, thin spark is a possible result of the impulse not working.

You can check ignition timing just like any other four stroke engine. Take out the spark plug, put your finger over the hole, turn the engine over until you feel pressure against your finger. Pressure indicates that the piston is coming up on compression. Watch the top of the piston through the spark plug hole (it's easy to see with a small flashlight on an LA) so you can tell when it reaches TDC. The impulse on the magneto should trip just after the piston is at top dead center. If it trips too soon, the engine can kick back.

I don't have the official timing procedure, but a quick check will tell you if its close enough for the engine to run. If your friend's engine is actually sparking a quarter turn before TDC, theres no way it would run. The spark would be happening with the piston at the bottom of the intake stroke. Are you determining this based on timing marks or on actually watching to top dead center? Timing marks have been known to be off.

If you don't get compression, then valve timing is off which means the camshaft is not synchronized to the crank. A quick check for valve timing is to watch the intake & exhaust valves open & close. You should be able to see the exhaust valve close and the intake valve start to open (sort of a rocking motion between the two valves) as the piston reaches top dead center on the exhaust stroke.

Hope this helps,

Keith

1. Confirm that the DC timing mark on the flywheel and the timing mark on the case do in fact correspond to the piston being at top dead center. If you pull the inspection plate off the back of the case, you can see the crank & watch when the piston is at TDC (or look through the spark plug hole & watch the top of the piston). This confirms that the flywheel is properly aligned on the crankshaft.

2. Verify that valve timing is correct per my previous post. This confirms that the camshaft is properly timed to the crank. If you have confirmed that the timing marks do in fact correspond to TDC, its probably easier to watch the timing marks than the piston.

3. Assuming that the timing marks on the flywheel and engine case align properly with both the motion of the piston and the valves, set the "DC" mark on the flywheel at about the 9:00 position, then turn the gear on the magneto in the direction it normally rotates until you feel some rsistance - this corresponds to the point at which the impluse spring engages.

4. Install the magneto (shift the magneto gear part of a tooth as needed to make the teeth align with the camshaft gear).

5. Turn the flywheel in its normal direction of travel until the impluse trips, and look at the relative position of the DC mark on the flywheel. If it doesn't align with the mark on the engine, increment the magneto drive gear one tooth at a time until the impluse trips at or just after the point at which the timing marks align. Turns out when I looked at mine that the magneto fires on every revolution of the crankshaft, so it doesn't matter whether you set timing on the compression or exhaust stroke.

Now that you've confirmed that both valve and ignition timing are correct, if the engine still doesn't fire there's a problem somewhere else. Either the spark is too weak, there's insufficient compression (most likely due to a sticking valve), or the fuel mixture is wrong. If you have spark, compression and fuel synchronized properly, it WILL fire.

Keith

Keith

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