Author Topic: Flat head hit and miss engine???  (Read 8844 times)

Offline Jasonb

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Re: Flat head hit and miss engine???
« Reply #135 on: March 20, 2023, 01:09:38 PM »
Wedge looks to be the right way up so it holds the arm in the up position.

Agree the interference which will increase as the weights get thrown outwards.

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #136 on: March 20, 2023, 01:30:47 PM »
Per--the wedge shape is facing the correct direction. The interferance you see is only there because I haven't shown the notch in the swing arm yet. Remember, when the hit and miss mechanism engages, it prevents the swing arm from coming down and letting the exhaust valve close.

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #137 on: March 20, 2023, 10:16:29 PM »
Today I machined the hit and miss mechanism and mounted it to the engine. I think it will work alright.--When I move the governor weights by had the weird shaped arm does easily rotate into place and if there was a notch in the swinging arm it certainly appears that it will catch it and hold the exhaust valve open. I'm not going to put the notch in the swinging arm until the engine is up and running. You only get one chance at something like this, and if you file the notch in the wrong place you end up having to machine a new swinging arm. I still have deburring and filing to do to make everything pretty, but first assembly is simply to show me that all the parts fit where they are supposed to.--


Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #138 on: March 21, 2023, 08:20:04 PM »
Great deeds were accomplished today. Ignition points and condenser were ordered and can be picked up tomorrow. New sparkplug was purchased and installed. New Viton piston ring and head gasket o-rings were picked up and installed. Finally made a new longer keyway bushing and was able to use it with my broach set to cut a keyway in the flywheel hub. (These broaches cost $100 each and will break if the keyway bushing is shorter than the hub being keyseated.---Don't ask me how I know!!) The keyway was cut in the crankshaft. There are some really nasty looking mig welds on the side of that flywheel that faces the engine, I will grind them down before I am finished here. So--For the moment everything is assembled, first time. I still have gaskets to make, add oil ports to the crankcase, and welds to grind. I also have to make a starter hub that attaches to the flywheel so I can use my electric drill as a starter.




Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #139 on: March 22, 2023, 07:17:21 PM »
Today I machined the starter hub which attaches to the flywheel and mounted it. Likewise machined the part which fits into my electric drill. I picked up the points and condenser and installed them. The two brass plugs that fit into the manifold above the valves were polished and then loctited into place. I still have to put in an oil filler pipe---haven't thought about it too much, but I've almost ran out of things to make.


Offline crueby

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Re: Flat head hit and miss engine???
« Reply #140 on: March 22, 2023, 07:44:40 PM »
... but I've almost ran out of things to make.
One more thing to make, engine sounds!    :popcorn: :popcorn:

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #141 on: March 22, 2023, 08:09:02 PM »
Getting close Chris.--Thanks for stopping by and saying Hi----Brian

Offline Art K

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Re: Flat head hit and miss engine???
« Reply #142 on: March 23, 2023, 01:43:50 AM »
Looking good Brian, won't be long now!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #143 on: March 23, 2023, 10:00:28 PM »
So, what did I do today?--I made and installed the gasket which goes between the manifold and the cylinder---the gasket that goes between the cylinder and the crankcase, and the gasket that goes between the crankcase and the baseplate. All from 0.030" waterpump gasket material from my local auto shop. I drilled and tapped the crankcase for a 1/4"-npt pipe plug, which according to various calculations and measurements will give me an oil level that comes up 0.125" on the bottom of the connecting rod at the very bottom of the piston stroke. I set the ignition timing. I set the valve timing. I flame hardened and quenched the cam and the cam follower wheel which were both made from 01 steel. I soldered the needle into the brass cap which adjusts the needle on the carburetor. I tested the carburetor to make sure that when air flowed thru the main body, it would create enough suction due to venturi effect to lift fluid from a tank mounted below the carburetor. I wired up the ignition points and condenser. I set the valve lash on the exhaust valve. I stopped at my fastener supplier and purchased a 0.013" wire diameter compression spring to be used on the atmospheric intake valve. What do I have left to do?--Fill the crankcase with oil and file the notch in the swing arm which the hit and miss mechanism latches into to hold the exhaust valve open during the miss cycles. I have to select and install a tension spring between the governor arms. Then maybe I'll try and start this engine!!!

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #144 on: March 24, 2023, 10:55:48 PM »
Today was a first try to run the engine. No go---no firing. Time for diagnostics. Pulled off the manifold, made up a blanking plate to cover the holes in the side of the cylinder, then bolted the blanking plate back on with a gasket. Pulled off the cylinder head and stuck my thumb over the top of the cylinder. When I did this and flipped the flywheel over, the engine would "bounce back" from compression. Tried it again with a layer of oil over top of the piston--engine bounced back , but not enough difference to indicate a piston ring not sealing. Took a good look at the o-ring head gasket and determined that it hadn't been flattened equally all around.  Sometimes this happens if the head bolts are too long---they bottom out in the cylinder before they really squeeze the head gasket properly for a good seal. Shortened up the cylinder head bolts and retorqued them evenly, ensuring a definite seal at the head gasket. Removed two coils from the intake valve spring. This is a really delicate dance on an atmospheric valve. You need enough spring pressure to close the valve, but not so much pressure that the spring overcomes the atmospheric pressure which opens the valve. Will try again tomorrow, after rechecking valve and ignition timing. I have a can of ether which can be a good thing to convince the engine to fire. Once the engine fires a couple of dozen times, the valves seal much better. My theory on this is that the steel valve deforms the brass valve seats enough to give a much better seal.

Offline d.williams

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Re: Flat head hit and miss engine???
« Reply #145 on: March 25, 2023, 02:20:18 AM »
Brian, I have all the faith in the world in your ability to sort things out and I know you’ll have it running directly.

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #146 on: March 25, 2023, 10:07:43 PM »
Good news at the end of the day.--The engine runs on it's own. Much monkeying with carburetor main jet and ignition timing, but for now it's a runner. I have to do more tweaking to get the engine running at a faster rpm, but things are looking promising.---Brian

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Offline crueby

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Re: Flat head hit and miss engine???
« Reply #147 on: March 25, 2023, 10:53:59 PM »
That's  great Brian!

Offline RReid

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Re: Flat head hit and miss engine???
« Reply #148 on: March 26, 2023, 12:00:56 AM »
Congratulations, Brian! How's the flywheel fan working out?
Regards,
Ron

Offline Brian Rupnow

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Re: Flat head hit and miss engine???
« Reply #149 on: March 26, 2023, 12:09:36 AM »
The flywheel fan seems to put out a good quantity of air, but something isn't quite right. The engine fires and runs but eventually it runs down and stops. None of the firing strokes are very powerful sounding, and the engine doesn't have proper compression. I'm quite sure that the valves are not leaking. I'm suspicious of the piston ring. Tomorrow I will pull the piston and change the Viton ring. It may have been damaged when it went down past the ports in the side of the cylinder when I installed it.

 

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