What have I done?

[fxp]

Ok, I'm sure this is simple, but just pretend I'm a complete fool (shouldn't be too hard)

I decided to try my hand at servicing the old girl (stocky standard 1966 170 Oz Falcon) this morning (complete engine novice, but I had the factory service manual so I figured I'd be ok). The car runs nice and smooth, but it's been running a little hot in Sydney's heatwave and after 6 months it was time for a little maintenance.

Anyhow, I flushed the coolant and replaced it, and did the same with the oil and filter. Engine bay got a bit wet doing it, but all seemed fine when I ran the engine after. Then the problems start. I pulled the plugs to check them and the gap. Gave each one a clean up (they were all in pretty good nick) and file and checked the gap to 0.032 (0.8 mm) and replaced each one in turn. Torqued em in and replaced the lead (no I haven't mistakenly swapped any leads). Now the damn thing is missing. Slightly rough at idle, but if I try and drive it she goes no where and feels like it's going to rip the engine off the mounts.

I started pulling leads, and it seems 1 & 5 are the problems (I think). Every other cylinder noticeably slows the engine when I pull off the lead. Pull the lead off these two and there isn't too much of a difference. I pulled all of the plugs out again to double check them and even swapped them around (2 swapped with 5), but no change, still seems I have 1 & 5 missing.

So am I missing something ultra obvious? I'm suspecting the leads, but they're pretty new, and all I've done is take em off the plugs and then put them back on.

 

[addo]

I emailed you.

 

[Funky Cricket]

did you bump your distributer? check the timing?

 

[MustangSix]

1&5 are next to each other on the distributor. Make sure:
1. plug wires not swapped
2. no carbon arcing inside the cap
3. point lobe or electronic reluctor still good
4. plug wires not shorted together or chaffing
5. cap is clean and dry inside and out.

 

[80Stang]

Was all the wires detached from the distributor cap at the same time? If so you may have plugged them in the right order (153624) but in wrong direction. Check that they are attached clockwise.

Seen one engine done that way, and had same symptoms.

 

[MercuryMarc]

Have you tried swapping the plug wires to 1 and 5?
I was certain I had not misconnected the leads, but it happened to me once.
It is the easiest solution to try and you'lll know in 15 seconds if your problem is solved.

Good Luck!

 

[Anonymous]

in case you forget, 153624 is molded into the intake (atleast on mine it is)

 

[Anonymous]

Engine bay got a bit wet doing it, but all seemed fine when I ran the engine after. Then the problems start.

Sounds like moisture inside the cap to me. As Jack pointed out "1&5 are next to each other on the distributor." So dry the Dizzy well and check for cracks too, and do all of the above

 

[LaGrasta]

Yup, sounds like water. If you let it sit over night, that should fix it. If it doesn't, pull the cap and look for water. A neat trick is grab the leaf blower and blow it into every crevice to extract the water from tight areas.
I do this every time I wash my motorcycles. It dries the water out of the engine area lickity split!

 

[Lazy JW]

Dry it with WD-40. That's what it was made for.
Joe

 

[fxp]

Guys thanks for the caring and sharing.

Update:
-Nope the leads weren't crossed.
-Pretty sure there was no water, but cleaned and dried it up anyhow.
-Points gap was tight so I opened that up a bit but it didn't fix it (didn't make it worse though)
-Couldn't see the timing mark when I put the light on it. The engine ran much smoother when I pull off 5 so I did that and low and behold the timing mark appears (at about 25deg adv)
-I tried getting the timing in with 5 on but can't see it anywhere. I pull it off and again it idles smoother and I can dial in the timing. Plug 5 back in and it goes to hell again and the timing mark disappears.
-I tried pulling 4 off to see if it would act the same as dropping 5 but no the engine just bogs down.

Any ideas?

 

[fxp]

had another look in the dizzy cap and there is a suspicious looking 'crack' inside between 1 and 5 contacts. I say crack as it's nearly invisible and looks more like a scratch. Is this the culprit? What is it doing? Forgive my ignorance but I'm a complete noob at this. I wouldn't have given it a second thought as it's so small, but being between 1 & 5 seems a bit too coincidental.

 

[ludwig]

Well, you have a cracked distributor cap. Take it out, get a high quality new one and replace it. Make sure everything is dry inside and out, then re-string your plug wires one at a time, making sure that they start and end at the right places.
Your shop manual should have a diagram of the plug numbers on the distributor and whether the plugs are numbered front to back. If you were an auto shop, you could charge $350 for a $30 job like happened to me before I got the 411.

 

[fxp]

got a new cap and rotor on order, but won't get it til Monday

So for the ignorant like me what is happening with this crack? Is it somehow shorting the two? Something to stick in the memory bank.

 

[Lazy JW]

got a new cap and rotor on order, but won't get it til Monday

So for the ignorant like me what is happening with this crack? Is it somehow shorting the two? Something to stick in the memory bank.

Yup

 

[fxp]

uh-huh

so that's why dropping the lead off 5 actually improved the idle? No short circuit if it's trying to short to an open circuit?

opening the bonnet always seems to be an education

Next question is what the hell did I do to crack the sucker? Water, impact or just plain bad luck? Would like to avoid future pain.

 

[ludwig]

Could be water splashed on a hot distributor cap or it is brittle and you scored it with a screwdriver or pliers. Maybe its time was up.

 

[MustangSix]

got a new cap and rotor on order, but won't get it til Monday

So for the ignorant like me what is happening with this crack? Is it somehow shorting the two? Something to stick in the memory bank.

Monday?? Where are you? Those caps should be common as dirt and on the shelf. :

It may not be a crack. It might be the trace from an arc. If you get a crossfire between cylinders it begins to burn a thin line. It might look like a crack but is actually a thin line. Either way, the cap is shot.

Keep in mind that electricity will follow the path of least resistance. If you can generate an arc inside the cap the resistance thru the plugs and wires was very high, or a lower resistance circuit inside the cap (due to water or a crack or something else) exiisted.

 

[weeds]

What Jack said. you may want to check the resistance on the plug wires as you replce the cap.

 

[fxp]

maybe common in the states, but not here. The XT (late 66) had a different cap. XP and earlier (60-66) are pretty rare these days. Tried half a dozen places, even Rare Spares, nuthin.

Trace of an arc sounds more like what I've got, but I'm a little confused as to why it continues to be a problem now that the water isn't present. The trace actually changes the resistance of the plastic? Anyhow thanks all for the assistance - lets hope Monday produces a positive result.