Engine back fired after upgrade

[Charles Akins]

Fellow A4 guys,

I converted to an electrical ignition last summer. After the conversion the engine started but ran poorly with backfires. I needed to do a lot or other rebuilding but with hurricane season coming up I put that off. Well the old M35 did well, going through Hurricanes Gustav and IKE with only a few rubs on the jelcoat and a broken glass lens on a non-functioning knot meter but no other damage. I rewarded the old girl with a professional rebuild of her sea cocks, standing rigging, mast footing and keel support plates along with a new propeller shaft and a new prop. With a now “new” boat I was ready to adjust the timing on the old A4 and get down to sailing.
One problem, the timing would not adjust. The engine back fired and had very little power. I discovered just cylinder 1 and 4 were functional. Disconnecting ignition wire 2 and 3 had no effect on engine operation. I was getting spark to all 4 cylinders; compression was within limits to all cylinders.
I struggled with this problem for several weeks. I finial went back to a mechanical ignition, with no improvement. I decided that the valve stems to 2 and 3 must be bent allowing the valves to be stuck closed. Now faced with a major engine rebuild in desperation I connected ignition wire 3 to cylinder 2 and to my delight I got an immediate surge in power. Wire 2 to cylinder 3 gave me even more performance. With my timing light I set her to 10-15 degrees before TDC and the old A4 hummed like a top. When I put it in gear it nearly pulled the dock down.
I have spent the last week trying to figure out how my firing order got changed from 1-2-4-3 to 1-3-4-2.
After a second discussion with Tom Stevens at Indigo Electronics we figured out I was thinking the distributor rotated counter clockwise like the fly wheel. It doesn’t. The distributor rotates clockwise!
When I first blogged about this I was told the A4 would run with wires connected backwards. That did not mean anything to me at the time. BUT

..................1...........
.............3..........2.......
...................4.......
1-3-4-2 COUNTER-CLOCKWISE is 1-2-4-3 CLOCKWISE and the distributor rotates clockwise
Hope my experience helps some of the other amateur mechanics out there.

Charles Akins

[tenders]

Nice. I did a midsummer tuneup about 10 years ago and replaced the cap, meticulously restoring the wires to Moyer specifications and photos.

The engine backfired constantly and wouldn't start. On a mooring in the rough Hudson River, it took me two weeks, several battery charge cycles, the purchase of a generator to recharge the batteries after the first grueling removal and replacement cycle, and even an incident of seasickness before the problem was solved. I also had some ether (starting fluid) on board and tried to use it to get the engine going.

One of the backfires set the entire engine compartment on fire from the ether--the scariest thing I have ever done. Had my boat partner not been around and executed beautifully with a fire extinguisher I think he and I and the boat would have been lost at sea while tied to the mooring--a most ignominious way to go.

In the end, and days after the ether incident, I was at my wit's end, and moved the wires around on the distributor out of nothing more than frustration. Then, suddenly, with a light touch on the starter: VA-VOOM!

It actually required solving the problem before I figured out what the problem was. My engine was at some point set up with the distributor installed rotated 180 degrees away from the factory installation. I never noticed this because I had previously simply followed the wiring sequence on the old cap when replacing it. Only with Moyer's manual to show me the "right" way to do this did I have the confidence to attempt to do things the "right" way.

Moral here: it's always something. Also, NEVER EVER EVER USE ETHER ON THE BOAT.

[rigspelt]

Both superb stories. Thanks for posting them. Reinforces my plan to have our mechanic go over the upgrades I've done during the refit. I was just telling him on the weekend how I've had the distributor out and rotated the shaft a few dozen times since it was last fired up in the summer -- that was the main reason I wanted him back at the first firing: to check my distributor reinstallation.

[Greg Kingman]

Timing Light operation on A4

Can you explain how to use the timing light in adjusting the timing on the A4? Obviously, there is no timing mark on the Flywheel so what do you shine your light on?
Thanx,
Greg

[adab1402]

timing is everything

just a quick thought ,timing is usually set a few degrees after top dead center ,or a few degrees before ,ladies choice . pull your #1 around till its on compression stroke ,pull the plug, stuff a rag or if your brave put your thumb over the hole and when it pops your almost there .now insert a screwdiver into the hole ,gently ,by hand, rock your engine untill the piston is at top of its stroke . now take some paint or a light coloured mark-a-lot and make your own timing mark where its convenient ,the timing light should work on #1 when you fire it up . fair winds adab1402

[rigspelt]

Can you explain how to use the timing light in adjusting the timing on the A4? Obviously, there is no timing mark on the Flywheel so what do you shine your light on?

This might help: http://www.moyermarine.com/forums/showthread.php?t=511

[Charles Akins]

Timing Light

I used induction timing light. Its operation is simpler than the older “direct” lights. There is a clip connection to a hot positive and its corresponding ground (even back to another battery if you have any doubt about the connection). The third wire has a clothes-pen like pick-up coil that clips around the # 1 ignition wire. The light strobes every time # 1 fires.
I painted the “post” on the crank shaft that is up with TDC #1 (finger in the spark plug hole test) with Office Max White Out. (BTW I plan to file a small notch at TDC in the crank shaft with a triangle file and fill it with white bath room calk when I get time.)
My fly wheel has a cover with a notch at 12:00 o’clock. You can make a gage to go on your fly wheel cove from a piece of typing paper and a drawing compass. Make a circle and fold it in half for 180 degrees repeat 90 and 45 and 22.5. Cut out the 22.5 wedge. Divide it into 4 equal parts. This will give you marks every 5.6 degrees. Past the slice of pie wedge to the fly wheel cover with the point of the pie section over the center of the drive shaft and the back of the pie from 12:00(TDC) to 1:30 ( 22.5 degrees before TDC). Remember the fly wheel rotates counter-clock-wise as you look at it and the distributor rotates clock-wise as you look down on it. (Sell the 7 left over wedges to other A4 owners for $4.00 plus S&H to pay for your timing light)
The strobeing of the timing light “freezes” the white timing mark at the point in the cycle where #1 fires. (Works best in dim light) Loosen the set bolt that that holds the distributor in position and rotate it until you get the best performance. A tachometer is the best way to detect this “sweet spot” but the sound of the engine is also very effective. For every 2 full rotations of the fly wheel the distributor only makes 1 rotation on the 4 cycle A4 engine. So there is a 2 to 1 ratio between the change in position of the distributor and change in timing related to TDC. The A4 is forgiving, my A4 runs and starts from just before TD to 20+ degrees before TDC.