Hand Start B

[45 JDB]

I read this forum every day and enjoy it very much. A couple of days ago I was reading some responses from a few of you guys about the different techniques used for hand starting the old Deere's. I have a 45 B and know that it is picky and has it's own little kwirks and sequences of proper choke and throttle adjustments in order to start. I noticed a few comments about turning the fly wheel until the piston on the right side is in compression and then rocking it back and forth a few times before completeing the stroke. My B usually starts on the second or third stroke but sometimes can be stubborn. It was having one of it's stubborn moments yesterday so I decided to try the rocking technique and to my amazement it fired right up. What is the science behind the success of this technique?

 

[John T]

Darn if I know?? For one I prefer to start mine on the Left cylinder cuz that way its ONLY 1/2 turn later until the Right comes up on compression n fires versus starting on the Right where its 1 1/2 turns till Left fires.......

If you have her up on the compresion stroke but instead of pulling her over to fire you rock it, seems to me like each rocking and that associated time delay allows compression to bleed off so when you finally do pull her over TDC to fire its under a lot less compression then it would be if you just pulled her ahead over the first time (no rocking and time delay and compression bleed).

If youre up on compression near TDC theres no other valve operation taking place, and whatever fuel n air already in the cylinder is what youre working with and rocking DOES NOT change that (other then compression bleed) other then perhaps the atomized fuel condenses out of the vapor state resulting in more raw gas tantamount to simulated more choking???????? Maybe the rocking time delay causes more choking effect (vapor state goes to raw gas) is why some start better that way THATS BOUT ALL I CAN COME UP WITH...

As I posted before, TIMING TIMING TIMING (Start Timing Impulse snap right near TDC) is critical for hand starts, too fast n she kicks back but too slow makes her harder to start. Then the right choking but NOT overchoke n wet gas foul the plugs. The throttle at a slow idle.

John T

 

[PBrowning]

Here's yet another small tidbit that may help some -- Not all John Deeres behave the smae way! (PatB)

From the John Deere Model "H" Restoration Guide, Chapter 8 - - -

"TIP: Start Engine With Nearly Closed Throttle

Most tractors start easily, however, there are those one of two in a hundred that give trouble. In most cases, these can be improved by placing the throttle in an almost closed position.

The higher velocity of air entering at the edges of the throttle disk helps to vaporize the mixture of fuel and air and keep it in a volatile state for starting.

With the throttle nearly closed, the amount of air-fuel mixture entering the cylinder is limited, lowering the compression.

With lower compression, the spark will more readily jump to gap at the spark plug electrodes; battery load is decreased, causing a hotter spark; and cranking rpm is increased (FSB 200-S, February 1953). This technique works equally well for hand-start models -- seems to help avoid flooding. ++++

 

[45 JDB]

Makes since to me! The secret to my B is throttle between 1/2 and 3/4 with full choke. It really helps if all the gas has either been drained or ran out of the carb at last shut down. I always close both my 3 way fuel valve and setimate bowl and run it out every time, seems to start easier that way. As soon as she coughs I IMMEDIATELY MUST turn the choke off or it's %$&* to pay. As stated earlier she got a little difficult yesterday and the rocking technique worked great. Thanks for the replies, I just wanted to know why this works and sounds like you guys explained it.

 

[old]

What it does is sucks fuel into the cylinders so when it fires it has a very rich mixture in the cylinder. I had an old guy tell me how to do that a couple years ago. He told me you should never have to spin the flywheel over more then 2 or 3 times to start one. But I rock it so it does that on the left cylinder not the right one since the left is the one that fires first. On a good day my B will start the first pull over on both cylinders
Hobby farm

 

[Lee B]

The main problem is that the carb doesn't vaporize the gasoline very well at the low air speeds generated during hand cranking. Blowing the same air back and forth across the choke plate by rocking the flywheel would allow for much more vaporized gasoline in that air without a subsequent increase in "liquid" gasoline which often spurts out the petcocks under various starting conditions.

One aspect not touched upon often enough for me is the fact that these carbs often have chokes that shut off 100% of ALL air thru them. This is NOT how a choke works best guys - it needs to be cracked open just a hair to let the air actually get into the cylinders after all...