HEI distributor cap worn or not?

[kikkegek]

he guys, help me out here.

the engine has been idleing a little rougher lately...not bad but noticeable.

took the cap of today and took a picture.

is this ok? or does it really look worn?





Its on there now for about 25.000 miles

[old Rusty C10]

there is crud on the contacts id replace it as best i can see in the pics

[88Jimmy4x4]

looks wet too...replace it

[kikkegek]

hi rusty: I thought it looked only like some carbons on the surface and was hopeing I could just sand them off with some sandpaper?

he jimmy: it looks wet because of the flash I used and it reflects in the picture. Its absolutely dry.

[motornut]

I think I see what 88Jimmy sees
moisture oily like,might be enough to make a difference

[bnoon]

It does look wet in the pictures but if it is indeed dry, clean the contacts like you mentioned with sandpaper and then... Here's the kicker... you need to test resistance from the contacts inside the cap with the corresponding leads on top of the cap. You should see less than 1 ohm on each one. Outside of a worn/weak spring on the rotor contact, there's not much else unless you want to test for cracks and that can be done with some talc powder, but I see no signs of arcing at all.

[kikkegek]

Originally Posted by bnoon

It does look wet in the pictures but if it is indeed dry, clean the contacts like you mentioned with sandpaper and then... Here's the kicker... you need to test resistance from the contacts inside the cap with the corresponding leads on top of the cap. You should see less than 1 ohm on each one. Outside of a worn/weak spring on the rotor contact, there's not much else unless you want to test for cracks and that can be done with some talc powder, but I see no signs of arcing at all.

Hi bnoon...thanks for the reply. I check the resistance, thats a good tip.

how would you use talc powder for seeking cracks in the cap? can you explain that?

I think the oil in the pictures is reflection from the flash, but I'll check that too just to be sure.

contact to the rotor is made, in my case, by a copper lip that touches the button in the cap:

the thing I am a little worries about is that the wear of the contacts is at the bottom. shouldnt the rotor pass in the middle of them? in stead of past the bottom? so should I maybe lift the rotor up a little (bent it up?)

see this picture (its from march last year)


as you can see in the picture, there is no spring under the lip on the rotor

[bnoon]

Originally Posted by kikkegek

Hi bnoon...thanks for the reply. I check the resistance, thats a good tip.

how would you use talc powder for seeking cracks in the cap? can you explain that?

You can check for a crack in the distributor cap with baby powder by putting some powder in the cap and distributing it around evenly by rotating it, swirling, etc. The crack (if there is one) will collect the powder and make a white line at the crack.

Originally Posted by kikkegek

the thing I am a little worries about is that the wear of the contacts is at the bottom. shouldnt the rotor pass in the middle of them? in stead of past the bottom? so should I maybe lift the rotor up a little (bent it up?)

That little bit of green/white/etc isn't wear. It's corrosion from the condensation that gets inside every distributor cap out there. The problem is that the corrosion can grow large enough to short out and come in contact with the rotor, which will cause a change in dwell as well as possibly cause damage to the rotor tip. Sand them down to bare shiny metal.

The one I'd be concerned with is the one in the 3rd picture in about the 7:30 position that looks a little black in the picture (usually carbon deposits). If it is carbon, then that means that path has too much resistance from either a bad wire, a bad plug, or both, and has been taking too much voltage/amperage to fire. Kinda hard to tell for sure, may just be my monitor making that one look darker than the others.

Originally Posted by kikkegek

as you can see in the picture, there is no spring under the lip on the rotor

Yeah, the spring I was talking about is sometimes under the button in the center/top of the cap where the rotor meets the cap. Could be that only HEI's and or certain versions of it use that spring. No biggie.

[kikkegek]

he bnoon, thanks for the explanation. Do you mean the second tip on the left from the bottom with the green/whitish deposit also on it? I'll check to which cilinder that goes, because I have two fouling cilinders and untill now was blaming bad piston rings and just accepting it...I'll check my wires for resistance and check the cap for resistance.

[bnoon]

I think we're talking about the same tip. Just look for black marks, that's the tell tale sign. Green and white can just be sanded off and you should be done.

[kikkegek]

Originally Posted by bnoon

I think we're talking about the same tip. Just look for black marks, that's the tell tale sign. Green and white can just be sanded off and you should be done.

something I might need to add is, I use:
1 - standard wires

measured them one time and found this:
57 cm wire gives 8,84 kOhm
83 cm wire gives 11,65 kOhm

I found in a couple of articles this is just fine
for example:
10-15kOhm is said to be normal
http://www.popularmechanics.com/cars...enance/1272351

6-7 kOhm (mis-typed in he article)
http://www.ehow.com/how_2296047_test...-wire-car.html

2. but I use a MSD-6AL
so I have a pretty good spark, multiple even up to 3000rpm

3. I have gapped the plugs to 0.0433" which is where MSD says you should start and slowly open them up

So I guess the total combination of those three cause the black carbon deposites on the tips...

could it?

[bnoon]

Everything sounds like it should be fine with your ignition after a general cleanup. Hopefully there's not any black carbon and it will just be a little bit of sanding and go. A tiny bit of carbon is OK for something that has been in service for years, but should be cleaned up with sandpaper.

One thing with the 6AL is you want to make sure it has 13.5V-16V feed (while engine running). If you have low voltage (like 12-10 or below running) you will start to get stumbles/hard starts/etc. Low volts will kill the 6AL box and run like poo.

Make sure you have a 10 gauge wire feeding both power and ground to the 6AL and that your primary and secondary battery cable grounds are both in good condition and large enough for the rest of your electronics.

[kikkegek]

Originally Posted by bnoon

Everything sounds like it should be fine with your ignition after a general cleanup. Hopefully there's not any black carbon and it will just be a little bit of sanding and go. A tiny bit of carbon is OK for something that has been in service for years, but should be cleaned up with sandpaper.

One thing with the 6AL is you want to make sure it has 13.5V-16V feed (while engine running). If you have low voltage (like 12-10 or below running) you will start to get stumbles/hard starts/etc. Low volts will kill the 6AL box and run like poo.

Make sure you have a 10 gauge wire feeding both power and ground to the 6AL and that your primary and secondary battery cable grounds are both in good condition and large enough for the rest of your electronics.

check!

I have thick wires to and from the MSD6AL and have very thick ground and + wires on my battery.

I also have connected the MSD-6AL the junction on the firewall where the voltage is kept at 13.4 Volts by the voltage sensing function of the alternator.

thanks for the heads up.

I will try to clean up everything and report back here...but autumn has started over here, so need to find some dry time...

thanks guys

[INSIDIOUS '86]

Get some good wires. Those ohms are silly. My wires only put out 40ohms total
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[88Jimmy4x4]

go to rockauto and buy a cap/rotor/plugs and wires.....they have good prices on AC-DELCO parts

[kikkegek]

my distributor is bone dry, so the "oil" in the cap is probably not oil, but reflection. Here are some pics to proof it. If it is, I wonder where it would be coming from?

[motornut]

Originally Posted by kikkegek

my distributor is bone dry, so the "oil" in the cap is probably not oil, but reflection. Here are some pics to proof it. If it is, I wonder where it would be coming from?

maybe around the vac advance

[kikkegek]

hi motornut...and where would that oil then come from near the vacuum device?

[kikkegek]

well...opened her up again tonight:
- no oil (that was probable reflection on the plastic)
- took some sandpaper and the carbon came of easy
- cleaned up the middle button
- bent the lip on the rotor up a little
- cleaned up the rotor tip
- cleaned the cap with a dry cloth

and put her back together...saved me a new rotor and cap, because these were just fine

[Dead Parrot]

One trick that sometimes will find high voltage ignition problems is to park the truck in a dark place and with the motor running, look under the hood once your eyes adjust to the dark. Any sparks jumping from wires to ground become much easier to spot. Pay particular attention to those going to the fouled plugs. Check around the rotor cap as well for spark going down the outside. But please remember, even if you can't see them, the fan and belts ARE waiting to bite you.

[kikkegek]

Originally Posted by Dead Parrot

One trick that sometimes will find high voltage ignition problems is to park the truck in a dark place and with the motor running, look under the hood once your eyes adjust to the dark. Any sparks jumping from wires to ground become much easier to spot. Pay particular attention to those going to the fouled plugs. Check around the rotor cap as well for spark going down the outside. But please remember, even if you can't see them, the fan and belts ARE waiting to bite you.

thanks, good advise

[mrjata]

One thing that might help you, helped others. I swear by Taylor plug wires. Super low resistance, fantastic conductivity. I have put on several set on race cars of different kinds, to tractors. They make that much difference. Summit used to have the best price. Get the Spiro Pro wires to avoid radio noise.

For the cap and rotor, sand everything with fine paper, 220 or higher, use wet/dry but use it dry. Don't use the stuff for wood. That leaves little parts of grit everywhere. If you can't get the rotor smooth and clean, replace.(cheap). The cap will polish up ok.

Bottom line, clean everything,and replace wires and plugs(to get a good reading). Make sure your connection to the cap is clean too.

pm me if you have problems, be glad to help.

[motornut]

Originally Posted by kikkegek

hi motornut...and where would that oil then come from near the vacuum device?

over the years i've seen oil/grease get in there,some grease is used there but
small gaps i figure like under the vac advance for the rod to move
seems to spread in from there
not a "leak" persay more a oily spray,residue