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Barry 
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Joined: 01 Oct 2009
Location: Rochester, NY
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 Topic: C Engine Rebuild
Posted: 17 May 2010 at 7:28am |
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Last Fall I asked for advice re low engine compression. The consensus was it needed rebuilding, so I did. New pistons, sleeves, rings, rod bearings, valve regrind, new valve guides and the head trued up. Also rebuilt the carb. Finally got her back together but am having trouble getting her started. I poured a little fuel in the cylinders and tried turning her over. It popped and spit out the carb. Without being primed I don't even get a pop, even after shooting ether into the carb. Plugs are dry.
I checked spark and it is good, the magneto fires #1 when the "Fire" mark is centered in the opening in the torque tube. Valve clearance is correct, plug wires are connected in the correct firing order (1243). The engine is tight enough that the starter can only push it over TDC once. Then it stops and I have to hit the starter again and I will make one more revolution before stalling. Thus I can't "spin" the engine ( I know this should not be necessary though). So, any ideas?
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Dick L
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Joined: 12 Sep 2009
Location: Edon Ohio
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Posted: 17 May 2010 at 7:53am |
If you are turning it over with a crank and looking at the flywheel at the time you get spark on number one compression stroke you want to see the TDC in the center of the inspection hole. Not the Fire line! If it is set at TDC and after it is running and you put a timing light on the inspection hole you will see the fire line. The advance in the magneto or distributor will make that adjustment when running not by just slowly cranking the engine over. The adjustment is made with the spinning of the weights inside.
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Dave Richards (WV)
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Location: Fairmont, WV
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Posted: 17 May 2010 at 8:00am |
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Barry sounds like too much friction some where. Pull the plugs out and let us know how well she turns then. What did you set the ring gap to??? Did you plasti-guage the rod and main bearings. Don't want to insult you but if the main or rod bearing caps are on backwards at any one point, the engine will act this way. You will get better reactions soon, but I thought these questions might help the others diagnose the problem better.
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BobHnwO
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Joined: 16 Sep 2009
Location: Jenera Ohio
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Posted: 17 May 2010 at 8:01am |
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Sounds like your engine is to tight,better recheck clearances!
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Why do today what you can put off til tomorrow.
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wbecker
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Joined: 29 Oct 2009
Location: STL
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Posted: 17 May 2010 at 10:10am |
What Dick L said is right on!
It must fire on TDC when hand cranked.
Bill
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Bill Long
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Joined: 12 Sep 2009
Location: Bel Air, MD
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Posted: 17 May 2010 at 3:00pm |
Barry, When all else fails you can use the "finger in the number one cyl spark hole" after removing the spark. When you feel compression near top dead center you should be ready to fire number one. Check mag to see if that is right.
I am not home but there is an excellent site that shows timing a B-C engine or I would post it.
I know, what is being disucssed above about timing is more accurate, but frankly, I never even knew the timing marks existed till I came on this site. I sure starated a lot of tractors using that tried and true method.
Remember you are not dealing with the sophisticated electronically controlled engines of today.
Take good care of my favorates brother - the C.
Good Luck!
Bill Long
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Barry
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Joined: 01 Oct 2009
Location: Rochester, NY
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Posted: 17 May 2010 at 3:07pm |
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I must have had a brain fart this morning. I meant to say the magneto was timed to the "Center" mark, not the "Fire" mark. My boo-boo.
Anyway, I don't think the engine is excessively tight as it cranks just fine with the plugs out, and I can rotate it with the crank OK. I probably have a weak battery though. I used plastigage to check rod bearing clearance and shimmed the caps accordingly. They are installed facing the correct way.
Dick, despite knowing your mandates to check ring end clearance, I flat out forgot to do that even though I fully intended to. Anyway, when I got the piston assembly in the liners I could push them down with my hand. It didn't feel any harder than I would have expected with new bores, pistons and rings.
I can tow it to try to start it, but if it doesn't start I'm going to have a real hard time getting it back in my garage. So I don't really want to do that until I'm pretty sure everything else is OK.
Right now two things really bother me. First, why did it spit back through the carb. I got a little bit of flame out of the air intake (no air cleaner on yet). Second, why were the plugs dry even though there was clearly gasoline in the carburator (some actually drained out). It's possible I didn't get it rebuilt correctly. Am thinking about taking the carb off my CA and trying it.
Will appreciate any additional thoughts from you experts.
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CTuckerNWIL
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Joined: 11 Sep 2009
Location: NW Illinois
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Posted: 17 May 2010 at 4:25pm |
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Barry, TDC comes up 2 times in the cycle of the engine. It sounds to me like your fire order is 180 degrees out of time. First retard your spark as far as it will go. Use the thumb in the plug hole to make sure number 1 is coming up on compression,stop it at TDC, then advance the mag to the point of spark making sure it is number 1 that sparks not number 4. If number 4 fires when 1 is on compression TDC it would normally back fire out the exhaust and tend to damage your ear drums. I'm just not sure you are on TDC with the spark at the right wire yet. And then again I may be all wet too. Charlie
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Barry
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Location: Rochester, NY
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Posted: 17 May 2010 at 6:58pm |
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Mr. Tucker, you are a genius! Timing was off 180 degrees. Once I fixed that she started and ran fine, although in need of some adjustments. Thanks a bunch to all.
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Dick L
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Joined: 12 Sep 2009
Location: Edon Ohio
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Posted: 17 May 2010 at 7:00pm |
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Don't start beating yourself up about doing something wrong. If you had the timing marks on the crankshaft, camshaft and governor gear you are good to go that far. You seem to have compression but make sure you have no less than .010 between the rocker arm and the valve end. After that it is getting the number one cylinder to fire TDC on the compression stroke which is the one nest to the radiator. As Bill Long tells you can get it close enough to run without checking the flywheel and hone in the timing after it is running by ear. What I suggest will place on exact fire line when running. Advance is 30 degrees so if you use the Fire line to set it when it sparks by slowly cranking you are now advanced 60 degrees and you are way off.
You can make them run without a carburetor bolted up to the manifold with a spray can of starting fluid. I have done it many times when buying a tractor that has set for a long time inside with gas in it which has it clogged it up and has been removed. That is a test to rule out spark timing as a problem.
The 180 degrees off will cause you the kind of problems which has been stated.
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CTuckerNWIL
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Location: NW Illinois
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Posted: 17 May 2010 at 7:47pm |
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I guess that is the second time I got lucky in the last week. LOL
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