Holden 186 Misfire

[jdobson]

Hi there, I have a Holden 186, it's developed a misfire. I've replaced the distributor cap, rotor arm and leads but the misfire remains. Tomorrow I'll take out and clean the spark plugs. Does anyone have any suggestions as to what might be the cause assuming the spark plugs are fine? It is a Bosch distributor with points, I know nothing about points to be honest, can these be replaced? Do they wear out?

Be grateful for any help you can provide, it was running fine until yesterday.

Thanks Jack

[bee utey]

Points require regular adjustment, lubrication and replacement. They cost around $10 per set and usually last less than 10,000km, and should be inspected every 2000 to 3000 km at least. The rubbing block wears and requires lubrication. The contact faces are silver plated and burn away slowly causing misfiring. More about setting points distributors in Holdens:

DISTRIBUTOR TIMING - Holdenpaedia (http://holdenpaedia.oldholden.com/DISTRIBUTOR_TIMING)

If you are unable to get excited by points maintenance, get an electronic distributor off a later Holden 6 and have a sparkie fit that. Once it's adjusted it stays in tune for very long periods as well as giving a much stronger spark.

Example:

Holden Genuine Bosch 6CYL Electronic Distributor 202 | eBay (http://www.ebay.com.au/itm/HOLDEN-GENUINE-BOSCH-6cyl-ELECTRONIC-DISTRIBUTOR-202-/370838188316?pt=AU_Car_Parts_Accessories&hash=item5657adb11c)

[jdobson]

Thanks for that, I'll try replacing the points first and see how I go from there.

[pk.hoarder]

Maybe have a look under the bonnet in the dark, if there is poor insulation somewhere (maybe on the distributor cap or coil) you might see a little blue spark. Happened on my 186, but problem was pretty bad by the time I looked, you may not see anything if it's only a small misfire.
Also check dist cap for any cracks or moisture as that can do it too.
Cheers
Paul

[ian4002000]

It might be a mechanical problem ....
Try pulling off spark plug wires to find out which cylinder isnt working and then change plugs around and see what happens.
If you can do a compression check of all cylinders and this will show a poor cylinder if it is the cause.

[jdobson]

Well that particular issue turned out to be the points. I replaced them, plus the distributor cap and leads. All working fine until the head gasket blew! So it's currently out of action whilst I have the head skimmed and valves renewed. I'd had my doubts over the conditions of the head gasket, it has been losing water but the oil seemed free of contamination. Whatever it was must have given up the ghost and suddenly it got very hot and the water had clearly got into the engine oil. Good job I watch the temperature gauge like a hawk! Managed to get home and now the head's off and being machined. Hopefully be back on the road in a week or so time.

[ian4002000]

Dont forget to use GM Head Stud Sealer or similar on the head bolts, if they still sell it....