blowing spark plugs??

[sexual_sushi]

hi all,

my daily driver (1974 260z) has had a bit of a rough time lately. got hit by a random woman at a set of traffic lights and after i got it back from the panel beaters it was only running on 3 or 4 cylinders.

 

Replaced 3 of the spark plugs with a few new ones i had lying around and then the next day the other 3 died. so i got 3 more new ones and replaced them so i had a fresh set of 6 in there. then went to take it for a drive and 2 of the other spark plugs i replaced initially, died. i have just put in a new coil and replaced the 2 dead spark plugs and ill drive it to work this week and see if it kills anymore.

 

so my question...  is there anything besides the coil that could kill spark plugs? i am yet to replace the ballast resistor but i will do this over the next week. i just wanted to see if there was anything else i can check/replace

[gav240z]

What do you mean "blowing spark plugs"? How do you know they are dead and not just flooded with fuel? What colour are they?

 

I use a wire brush to clean mine up if they get fouled from a rich mixture.

 

Usually if this happens there is something else going on anyway, rich mixture, incorrect timing.

 

Also are they the right gap for your application? I use NGK plugs usually.

[gav240z]

Ballast Resistor shouldn't cause you any problems. When you put electronic ignition in a Z you bypass this anyway.

[sexual_sushi]

well they appear to be dead, it may not have killed all of them but they needed replacing anyway. they are ngk bp6es. set to .8mm (as far as i know its a fairly standard engine, l26 round top twin su's). there is spark when i take the lead off and hold it against the valve cover. and the same plug won't work when swapped to another cylnder that was working. they are quite black but not fouled up with gunk, however i have cleand them with a wire brush and wet & dry between the gap and it didnt seem to help. im thinking i may have fixed the problem with the new coil but ill see how it goes 2moro.

 

does 'killing' a plug sound unlikely to you? I'm thinking my next step is to get a su rebuild kit and then take it to a shop to get tuned ( i haven't had it tuned since i first got the car 3 years ago). they don't really want to touch them unless they have been rebuilt recently as "they can spend hours on them and not get them to match." this was a guy at ultra tune who had a rolling road. if anyone in brisbane can recommend a good shop for tuning im all ears.

[gav240z]

They don't really want to touch them unless they have been rebuilt recently as "they can spend hours on them and not get them to match." this was a guy at ultra tune who had a rolling road. if anyone in brisbane can recommend a good shop for tuning im all ears.

 

He's spot on really, if the SU's are stuffed (mainly problems with the bushing of the throttle shaft) then you will never get them right.

 

Killing plugs in such short time seems unlikely to me, unless they have been dropped etc..

 

The biggest problem I've had with SU's and Spark plugs is the mixture being too rich. This causes them to foul up but usually a quick clean with a wirebrush and there good to go again.

[pauly_adams]

this is going to sound strange but try buy the plugs from a different shop, i had this problem last year the plugs with a fulty batch of plugs, they seemed to be only a little black but where not gunky etc. finaly after going back to supercrap for the third time they told me to go see repco and buy a set from them as they have had fulty stock before, after i bought a set from repco i have had no problems since.

 

 

cheers pauly

[Hunter]

How old are your sparkplug and coileads?

 

This could not be causing your problems could it?

[sexual_sushi]

thanks for everyones replies...

 

the leads are 1-2 years old max, the spark plugs were quite old so im not that suprised the 5 of them could die. 2 died one day, then 3 the next. but then after i replaced them, 2 of the new ones died and wouldn't work after cleaning them. i thought there was a possibility of getting a bad bunch of plugs but because the car killed 7 plugs in about a week I was a little dubious.

 

After replacing the coil (it was quite rusted anyway and probably hadnt been replaced in a while) and the last 2 dead plugs the car ran perfect today to and from work. i will drive it for the next week and hopefully it will be all good.