Continental F series cylinder miss

DW1307

Member
I'm working on an old Clark forklift with an F series Continental engine, it's either an F-140 or an F-162, but shouldn't make any difference. It sat for years and I got it running fairly easily, but I have a miss on #2 cylinder. I checked compression on all 4 cylinders with all the plugs removed and get a fairly even 130 to 140 # in each. Good (copper) wires with strong spark at the plug. I tried switching plugs, wires etc and still #2 cylinder not firing. The firing order is correct 1-3-4-2. Any ideas?
 
on forklifts sometimes the firing order is opposite of what you would think. no 1 isn't always by the fan.
 
Well, that's all I have to go by, #1 at the fan end. Every Continental I've worked on was that way.
 
Take out the plugs,take off the distributor cap,turn the engine over by one hand while you block #1 cylinder with your thumb,pull the engine over in normal direction and you will feel the pressure under your thumb when it's coming up on compression stroke,bring the TDC marks to match,look at the distributor rotor,see which plug lead the rotor it's pointing at,that should be #1,next wire on the cap #3 then#4 and finish at #2,on all four cylinder engines #1 & #4 are always opposite each other and so #3 & #2,look closely at the cap for a crack,often the cap can crack between two leads,check the plug lead is not grounding,the compression is ok but a valve could be sticking a bit at speed try a shot of upper cylinder oil and see how it goes.
AJ
 
Well in my opinion if the firing order was not right ( and I think you are right) it would miss on either PAIR and not on that single cylinder. For years I messed with a lot of those but has been 30 years ago. I am thinking the culprit is your 130/140 lb compression. That is right on the edge of running. Fresh engine would be around 180 (I am thinking) . I would bet you have a valve that is just not hardly closing or leaking there on the # 2 because nothing changes when you move plugs ect. Has to be confined to that cylinder. Warm the engine up, take the plug out and add just a little (can,t stand much) oil to that cylinder and try it. Might bring the compression up if it is a stuck ring. Keep us posted I am interested in what it turns out to be.
 
Look for a vacuum line off of its port on the intake to that cylinder. A bad intake gasket will also produce that result. Swap spark plugs to see if that changes the misfire. Engines run with 50 psi of compression (ask anyone with a single cylinder stationary engine from the early 1900s it is not that). Jim
 
I read the other comments and it would seem all the bases have been covered. You got an incredible reading on compression and that alone would sideline many problems. I work with old engines when the high is just over a 100 and may have one way low and will run on two or three for awhile until the rings free. So my guess is the #2 exhaust valve guide is full of varnish or other sticky stuff. With all the plugs out doing compression check the valves are only turning very slow compared to a running engine. The spring pressure is enough in slow motion to close the valve. So once the motor is started the exhaust valve is not closing you get no fuel/air mixture therefore no fire that cylinder. the proof is in the pudding as they say. Start the engine and keep it running slow as you can for a few minutes. Stop the engine and pull the plug and it will be dry. If its wet the pudding is in my face!
 
I already tried swapping spark plugs and same results. There are no vacuum lines, just a plug on the intake side of the manifold.
 
Really, the 130# compression is quite good on that old flat head engine. I've had ones with uneven compression with the highest cylinders being around 100# and the weakest maybe 40 or 50# and they still ran.
 
I sort of already did that and I think the plug was dry, but I'll do it again to be sure. If I had the compression gauge screwed in with the engine running that would prove that I have good compression with the engine running. I'll try it again tomorrow and see what happens. Thanks for the reply.
 
Another thought is to take the tappet cover off and see if the valves on #2 cylinder are closing completely.
 
Well, I played around with it some more today, and still no answer. First I brought #1 cylinder up on compression and had rotor heading towards the hole that is currently # 1 so basic timing seems correct. I didn't check the timing mark for TDC , but I'm sure it's correct. It's cold out and timing hole on the flywheel housing isn't easy to get to. Next.I ran the engine with the compression gauge screwed in and got 130# with it running at idle. After that I ran it with a clean dry plug in #2 and it came out wet, not a lot, but wet for sure. Just for fun, I moved the wires around in the cap a few times and it wouldn't run at all, just pop out the intake. I'm stumped, I've worked on a lot of these engines and never had any thing like this.
 
Bad intake manafold gasket on #2 cylinder. Use a propane torch with the head taken off to whiff propane all around the area where #2 intake hits the head. A second thought is to put a teaspoon of gasoline into #2, then the plug, and start it. if it runs briefly on 2 you know it is intake of fuel that is at fault. Jim
 
It's easier to take the manifold off than the head, so I might just take it off and replace the gasket. I'll try gas in the cylinder, but considering I get a wet plug when I run it?
 
What's the point of warming the plug? I already started with a clean dry plug and after running a few minutes, it cam out slightly wet.
 
Update on the Continental: It was driving me nuts, every basic thing I tried didn't help, so I ended up taking the head and manifold off. I found a broken valve spring on #2 exhaust valve. If the exhaust valve isn't sealing on intake, it wouldn't suck in the fuel/air mixture. Anyway, I'm going to do the valves and seats and put it back together and hopefully the mystery is solved.
 

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