72 Johnson 85hp half fire

[Tubbsharper]

Cant get fire to plugs 2&4 1&3 fire hot, done pulled flywheel an checked the stator for cracks and or leaks all good there the distributor looks damn near new just don't see it going dead on 2 plug wires at same time.:grumpy::crazy:

 

[F_R]

Pull flywheel and check breaker points. They must be gapped to exactly 0.010". While you are in there, clean and re-lube the anti-reverse cut out ring. Use EP grease, very sparingly.

 

[Tubbsharper]

Okay got out and checked the gap its what the manual states it to be set and its all lighty lubed and clean just stopped firing on 2&4 the other day. ( E.G. Half burnt distributor? )

 

[Faztbullet]

Distributer cap or wire ends burnt off in boots

 

[Joe Reeves]

Okay got out and checked the gap its what the manual states it to be set and its all lighty lubed and clean just stopped firing on 2&4 the other day. ( E.G. Half burnt distributor? )

In checking spark directly from the coil... set the air gap to 7/16"...... From each spark plug lead, to 1/4". The air gap is important... nothing else will do!

If indeed you do not have any spark on cylinders 2 & 4 (port bank), double check the points as follows below.

Regardless of what the manual states.... clean those points with either lacquer thinner or acetone, then set as instructed here.
********************
(Point Setting Of Battery Capacitance Discharge)
( Ignition Models - 1968 thru 1972)
(Some have points - Some do not)
(Joe Reeves)

The points must be set to .010 but no wider than .010..... BUT in some instances due to a possible slight inaccurately machined crankshaft lobe or a slight offset of one set of points, a setting slightly less than .010 would be required as follows.

Whether the crankshaft has two or three lobes, when setting the points, check the setting of the points on each individual lobe by rotating the crankshaft by hand.

You may find that setting one set of points to .010 on one lobe, then turning the crankshaft to the next lobe, the gap measures .011 or .012 (too wide). This is where you would need to close that gap down to the required .010. A gap too wide can result in a ignition miss when throttle is applied.

Bottom line, pertaining to the point setting of your 1972 85hp model at the various lobe locations
____ .010, .009, or .010, .010 is okay____ .010, .011 is not!
********************

Tubbsharper: To be sure all of us are on the same page The cylinders on a V4, standing in back of the engine, facing the spark plugs are numbered as follows.

2.....1
4.....3

You are speaking of the port bank, cylinders 2 & 4 ?

 

[F_R]

Agreed, some people expect too much from those things. A lot of spark strength gets lost as it goes through the plug wires and distributor. Don't expect more than 1/4" spark gap at the plug wires.

EDIT: And don't expect it to run well on surface gap spark plugs. Maybe they did in a perfect world.

 

[Tubbsharper]

Has new J-plugs and coil/sparkplug wires(cheaply thanks to joes post with the brass screw terminals) so if one of the points is off or not working will that cause 2/4 not fire it hit on all 4 ,it ran for about 5-10 mins then coughed. Then I could pull plugs 2/4 off and not get shocked. I have strong power out 1/3 enough to start. Just stumped, don't want/need to throw money in to it on a part that is still working :facepalm:

 

[racerone]

Does spark jump a gap of 3/8" or more on #2 and #4 leads, yes or no ?

 

[Tubbsharper]

Define where the gap is. I've set the braking point gaps back to .010, they were both off by a smidge. still just firing on plug wires 1/3. both breaker points are new looking compared to what I've seen on some other models, everything's good till it goes into the distributor. just never seen one burn up half way. my flywheel it's good all magnets are Intact ,newish stator passes test. breaker points are lightly lubed and like I said are spot on what there supposed to be. Any way to test a distributor was told to check while engine was running,but what's to check it's not firing on 2&4 replaced plug wires boots spark plugs ect. This list goes on.:noidea: It's down to only one thing "The hardtofindcostly" Distributor-you know that black thang with the pentapuss spark plug legs.:Cry:

 

[Faztbullet]

Points will not effect just 2 cylinders......

 

[racerone]

There are 2 sets of points.--------MY bet is on a problem there !!

 

[Joe Reeves]

One set of points fires the starboard bank... the other set fires the port bank. The lobes on the crankshaft are 180 degrees apart... think about it.

Post reply #5... If the points are not set as I listed, they'll give you a problem.

You going to answer my question Tubbs?

 

[Tubbsharper]

Yes I have set both points rotating checking the lobes and watching my points even went out an Bought a new filler gauge... Do I stick a impact on'r an turn it over an look for a spark in dark between the points or how can I test them without buying new ones

 

[Tubbsharper]

Like I said I have already checked
1.set the gaps as joe stated above.
2.went through all wires sprkplg,ect.
3.tested all electronics stator,coil,amp,ect.
4.flywheel it's good.
5.all clean an lighty lubed.
6.new plugs.
7.pulled all hair out:crutch:

I also want to thank anyone who has posted it has been great advice better then cylimers.

 

[Joe Reeves]

Tubbsharper: To be sure all of us are on the same page The cylinders on a V4, standing in back of the engine, facing the spark plugs are numbered as follows.

2.....1
4.....3

You are speaking of the port bank, cylinders 2 & 4 ?

In a PM, something different was said and that's why I ask.

 

[F_R]

Common sense goes a long way in diagnostics.
1. The stator ring charges the battery. It has nothing at all to do with the ignition system (unless battery is discharged).
2. The coil and amplifier fire all four cylinders.
3. You replaced the plug wires, so they should be ok unless they are arcing out at the dist towers. But check their resistance with an Ohm meter anyway, "just in case".
4. The breaker points in that system carry very little current. That is why they never burn up.
5. Everything you say points to one set of breaker points not making contact. That would kill spark to two cylinders. Use that Ohm meter again to test them. Unplug the wire connector going to the breaker plate and connect one meter lead to it (the one going to the breaker plate). Connect the other meter lead to cylinder block (not to breaker plate). Set meter to lowest Ohms scale and rotate crankshaft while observing meter. Should go to zero and back to infinity four times per revolution. If not, there is a problem with the points or the ground wire.

 

[Tubbsharper]

Yes the 2 left/port/2&4 cylinders. Going to go out tonight or tomorrow and switch the condensers around on my points an see if it makes any difference. Spoke to a hand full of decent mechanics but all just scratch there heads

again sorry joe you've been the best help so far

 

[Tubbsharper]

And yes F_R I've done been up and down all that 2×3=9

 

[Tubbsharper]

Getting a same year over cooked motor this weekend looks good but someone didn't use there muffs might swap the timer base and give that swing

 

[racerone]

?----There are no condensers on that system !!