dang-it compression and spark but not starting

[surfjunkie]

dual carb 701 that has good compression 150ish both holes, plugs spark when hold them against engine (blue spark?) spray staring in fluid in carbs-nothing, spray in cylinders-nothing.

this engine was burning off starter fluid last night. now doesnt even cough or sputter or pretend to try to start.

wth? any suggestions

engine had been filled with oil by previous owner. bendix was rusted and would not let engine turn over and i guess they poured oil in to free up engine not realizing the problem. so much so, oil was all over plugs. i had to remove carbs and intake and tip it on its side to pour out all the oil. 1 cup poured out. but engine had run the night before with all that oil in there. now plugs look clean, almost dry, when i check them after trying to start. have tried a different start/stop switch which is known good and tried with black/white plug disconnected.

 

[surfjunkie]

reeds looked ok when i had intake manifold off.

 

[CarterB]

Check stator plate timing

 

[surfjunkie]

ok will do. but nothing should have changed since it did run. i wouldnt think. i did have to have all that apart to clean up the bendix issue....but did that before it ran and havent messed with since. maybe i didnt get it tight enough and it moved

 

[SmittySX]

Did you put in "new" plugs...?

 

[surfjunkie]

ok so my flywheel key was sheared. but the engine was turning over so not really sure i understand a) if key sheared how is bendix spining the engine and b) if engine is spinning, which it was, why would that cause it to not start and 3) what caused the key to shear. (i did not torque nut on flywheel just tightened it as seemed reasonable) most likely the culprit but can someone help me understand how and d) what is torgue for flywheel nut?

can i just throw a new key on there tighten to spec and try it or was any damage done with all that cranking

thanks for helping a shade tree mechanic minus the tree and the mechanic

 

[Harbor]

Inspect the key way in the crank and the key way in the flywheel, if both are good and no other visual damage install a new key and torque flywheel to 51 pounds.

Crank is tapered @ the end helps lock it.

It's not a lot of work for the starter to spin the flywheel against compression and it's at a slow speed. When the engine fires the crank spins away from the flywheel very fast with much more torque.

Some brand Keys ways fail more than others, inconsistent heat treat etc. hand tightening flywheel does not help but they fail even when properly torqued. Iam sure all that oil didn't help as well.

Every thing needs to be clean and dry

When the flywheels out position spark no longer happens slightly before TDC. Yours could have been firing the plug on exhaust after TDC

 

[Harbor]

Good find! Kudos

 

[surfjunkie]

oh i figured it would run, just not well, if the timing was off. makes sense though. thanks for the response!

couldnt see any damage. but if you dont know what youre looking for its hard to know if everything is ok. there is a scrape on the flywheel keyway where im sure the key rubbed but when i run my finger over it i dont feel the scratch. ???

 

[surfjunkie]

with all that oil in the crankcase could it have in essence hydrolocked briefly and sheared the key? seemed like more and more oil was getting up into the combustion chamber as it would start it and run for a few seconds. the plugs were getting increasingly covered in oil as this process was happening

 

[Harbor]

Sound like it will be fine then. I have some on mine too. A used wheel I recently bought has a chip out of the key way in the area of keyway when installed, it's small just kinda took the corner off, prolly happened from a broken key way too. Iam running it without issue so yours sounds ok

 

[Harbor]

Good point but how about a small momentary hydro lock condition from all the oil in the cylinder, crank stopped suddenly and flywheel kept going

 

[Harbor]

Use an OE keyway.

 

[surfjunkie]

will do. rounded side goes into crank right?

 

[Harbor]

Yes

 

[surfjunkie]

running like a champ now. thanks for all the responses!

 

[Vumad]

Kind of skimmed, someone may have already said this.

Compression is 0 when plugs are out so cranking is easy. Bad starter, bad cables, etc that causes low voltage issues can make a ski with spark the way you tried not have spark when the plugs are in.

The correct way to check is with the plug light tool. It goes between the boot and the plug and lights up when cranking. That way you know you have spark when the plugs are in.

 

[mybad]

Great job helping this member. How bad was the corrision on crank?

 

[surfjunkie]

Great job helping this member. How bad was the corrision on crank?

Because of all the oil inside and outside this engine it has no corrosion any where. It is the cleanest almost 20 year old engine I have ever seen. Crank looked perfect to this novice crank inspector

 

[Harbor]

One more point, the flywheel taper locks the flywheel to the crank and key way is for timing flywheel to Crankshaft TDC