VH4D Bob's theory

So I couldn't resist driving all the way home 3 hour drive to put Bob's idea to the test, we'll I found a stiff wire , removed spark plug number one, snaked the wire down past the lifters and let it rest on top of the piston, I then hand cranked the engine until the wire rose, when it appeared to be done rising I was at 10:00 I continued to crank the engine until I hit 12:00 it's kinda hard to tell but I don't think the piston went down at all from 10 to 12 so I called 12 TDC. Next I removed the mag spun the gear until the rotor was pointing at number one turned the gear just a little to see the X thru the site plug, and reinstalled the mag. Then I went with the stock firing order 1342 . Before installing the plugs I turned off the lights in my shop and hung the plugs attached to the wires where I could see all 4 and once again hand cranked the engine, the firing order is now correct 1342 . I set the flywheel X at 12 and when that mark comes around the rotor snaps and the plug sparks at 10 so am I off a little? I guess what I'm saying is it seems TDC is 10:00 and the rotation down begins maybe 12:30 1:00? I tried to start it with calling TDC 12 and didn't get anything so should I try 10:00 as TDC? Remember the snap and spark happens at 10:00 but yet it seems the piston from 10 -12 kind of sits there doesn't go up or down, would changing TDC to 10 make a difference ?If I reset the flywheel to 10:00 the mag should be reset to the same position correct ? x thru the window? I have to be close I just thought if the timing is only a couple cranks off it would still at least try to start but I got nothing.
 
I just took a closer look and placed a wire in number one again and as I turn the flywheel the wire rises and stops dead at 10 and doesn't move until 12 then starts going down. So where should I set the flywheel X 10 or 12 ? Just had to confirm exactly what she is doing besides driving me crazy!
 
I would set it at 12. If the piston isn't at TDC on the compression stroke it may kick back when the plug fires. Make sure the rotor is at the No1 plug tower. Hal
 
If things aren't lining up where they are supposed to be according to the book, I think you are going to find the people who worked on it for you got the timing marks off when they put it together. If it was put together right then you should be seeing the other marks in the right place.
 
El Toro, the DC and X vane at the center-line of number one and three cylinder the X on the magneto gear visible through the lower half of the inspection hole. Find number one wire tower on the magneto. clockwise number two next, then three and last number four. It's that simple, it's in the manual.
We all know that the piston does not stay at TDC when the crankshaft is moved just a couple of degrees, either direction.
 
Scott,
Here goes nothing,I just pulled a couple of VH4 cranks out to confirm what I remember.Both keyways front and rear [flywheel and pulley ends of crankshaft are in line].Mag snaps at 10:00,centerline of cylinder period.........Mag is set up at 12:00 so you are not fighting impulse dogs in mag.Flywheel keyhole lines with fin with X on it,Pin for hand crank in crankshaft lines up with DC fin on flywheel.Mag also has to to timed internally on rotor to be right.Valve timing is checked by observing intake valve just starting to open and crankshaft at TDC.No 1 throw on crank is the only one that is in line with TDC marks every other throw is not in line with any others.I know I am not remembering everything,but it should get you going.Ralph
 
Made a slight mistake below, you are right install magneto when the DC, X marked vane is at the vertical centerline mark on the shroud.
 
The flywheel keyway should be at 12 o'clock when No piston is a tdc on the compression stroke. Hal
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Well, thanks for all the responses and I hate to sound like an idiot but what should I do now? Here is what I know for sure I have,
1. fuel
2. spark at 1342 starting when #1 is at TDC
3. TDC was established by taking a wire and snaking it down #1 spark plug hole and cranking the engine by hand.
4. There is appears to be a flat spot where the piston starts to switch from going up to down watching it closely and hand cranking it slowly at 10:00 I reach TDC and the snap and spark happens.
5. The X on the flywheel fin is at 12:00 sort of the end of the upward stroke. and that's where the book said to put it.
6. The mag rotor/coupler is pointing at number one dist. cap hole and the X on the mag gear is seen thru the site plug ( per the book)

It seems I am correct with everything except maybe the x on the flywheel , should that be at 10:00 ? remember the plug sparks at 10 not 12 do you guys think the spark happening at 10 the piston may be starting down just a little at 12 maybe I should call 10 TDC not 12???????????? am I close or what?????
 
2 Thoughts

1) make sure you timed mag to compression stroke and not the exhaust.
2) how are the plugs, as much as you have cranked this to try to start it they should be really fuel soaked, a new dry plug set to the proper gap sure would not hurt.
 
Hey Jo,
huh? Time mag to compreesion stroke? Not sure what you mean, the only thing I did with the mag was made sure the coupler was pointing to number one and the X on the one gear fin was seen thru the inspection plug?
 
Thanks Hal, I just watched it and the guy said 23 degrees before the TDC the spark occurs wouldn't that be around 10:00? because that's what I have now.
 
Pour about a tablespoon of gas on top of No1 piston. Install the plug and make an attempt to see if the engine fires when trying to start the engine. Hal
 
I never really checked where the rotor was at time of spark , I just followed the book , made sure I was pointing at number one, made sure X was visible and married the mag to the other gear.
 
The piston does move between 10:00 and 12:00, but the amount is very small which is why you can't see it. If movement stops at 10:00 and starts again at 12:00, an argument could be made that TDC is at 11:00.
But it sounds like you should go with the marks in the manual, as it seems like you are in the ballpark.
 

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