1972 Beetle - recommended plugs and wire set

[rrb6699]

my bug started "missing badly. upon taking #2 plugvwire off I found the clip totally rusted. I tried to clean it up, but there must be other wire(s) also bad.

just gonna replace the entire set, rotor cap, etc.
should I use copper plugs? hot or cold fire plugs and would 8mm wire set be best?

thx

[Bruce2]

Get Bosch 09001 spark plug wire set. This is a top quality set, don't buy anything else.

The proper spark plug for a 72 Beetle was a Bosch W8AC. It has been replaced with a WR8AC. But first you must determine if your engine still has original heads that take ½" reach plugs. Some of the newer replacement heads require a 3/4" reach plug.
Do not buy a colder or hotter plug. You need the neutral heat range plug.

[rrb6699]

most plugs dont have much in the way of specs listed. I guess ill have to measure the reach. I'm pretty sure, but, not sure the heads were ever replaced.

it looks like the engine was replaced due to the engine number starting with a 126 number indicating it was a generator motor at one time.

don't know if those engines had any specific differences from the auto engines.

[sideshow]

Because of the way threads are cut the suggested practice is to not vary brands to reduce wear of the softer head threads.

Bosch copper core is probably the most successful of all time, my second choice would be NGK often easier/cheaper to find (today) and high quality.

The charging system matters little, check the hole depth to determine if long reach plugs are required. The odds are against you that after 45 years the head is the original.

[rrb6699]

ok I need to double check the heads but how do you tell? is there a way without dropping the engine? to measure reach do I put #1 at TDC and measure depth to the piston?

its possible that sometime in the past some stripping occurred on my #2 plug. I drove it when I first got it when it started running similar to the way it happened last week except it got really loud. I found that plug had popped out.

I put it back and it seemed ok, but, I can help think its not sealing totally. maybe it was stripped once.wont know till I get the new plugs.

so don't worry about the wire gauge? I'd think 8mm would be better than 7mm. true?

I'll go with Bosch copper core. which plug number? regardless of the reach wont it be the same plug?

[sideshow]

First of all, if your ejecting a threaded insert replace both heads. However if just the threads are poor, time sert that hole.

I would take a scrap of AC (110V house hold solid core) bend a hook on the end, 1/2" and 3/4" are the most common. Bore wise 14mm and 12mm are the most common.

The quality of the insulation is more important; safe bet the bosch\ silicon stock. I don't like the bosch solid core rubber stock (they harden up).

[rrb6699]

took the plugs out and cleaned them up. not to say they're right, but, they are 1/2" plugs.

it fires much better but, one cylinder still missing. gonna do continuity check on each wire to see if its a wire. I cleaned the rotor up last week.

there are Bosch Supers WJ6?s in now. none were fouled just normal looking. some soot. its gotta be a plug or wire. I suspect a wire first.

I will get these running until I get the plugs & wireset. I'd rather order these online if there is a better place than AutoZone.

so get the WR8AC plugs and Bosch 09001 wireset. silicone covered.

[Bruce2]

Because of the way threads are cut the suggested practice is to not vary brands to reduce wear of the softer head threads.

I've never seen any manual suggesting this, and never heard any mechanic say this, so I think it's a dubious claim.

I'd think 8mm would be better than 7mm. true?

If you get the Bosch 7mm wires I suggested and you keep them in good condition, they will outlive your engine. Sets of wires are very cheap right now on ebay.

regardless of the reach wont it be the same plug?

Different reach plugs have different part numbers.

[rrb6699]

I would think plugs thread should be designed to strip before the block threads in the head. true? that's how I'd design things.

to update, I cut all the wire ends and replaced connectors. the car runs perfectly but, at first was still missing for the first 8 miles or so of a 15mile trip I took.

then it started firing. the car runs with a lot more power.

however, I still intend to replace things. these plugs and wires have about 50k miles on them. although I agree wires should last if not damaged. these are 8mm with Bosch Supers . I'm not sure of the plug number. I didn't write it down but remember W6J something like that.
these are older colder plugs I think.

[Piledriver]

I would think plugs thread should be designed to strip before the block threads in the head. true? that's how I'd design things.

Tough to pull off with aluminum heads and steel plug bodies.

[rrb6699]

I still think it would have to be intentional to strip the head.

[Piledriver]

I still think it would have to be intentional to strip the head.

Much harder to do with 3/4" reach plugs, but still happens all the time on many models of cars.
I'm talking new cars.

It usually works like this:

An improperly torqued plug can remove all the threads in a few thousand miles, or instantly.
A loose plug can beat up the threads and blow out or leave them weak so the next time anyone tries to tighten properly, the damaged threads pull out.

Or you could install non-nickel plated champion or autolite plugs and just unscrew the threads along with the plugs because they welded together.

Good mechanics use a torque wrench on plugs and wheel lugs (aluminum wheels anyway) religiously.
Its a good habit. Don't guess.

Milk of Magnesia works great as high temperature antisieze, I have a bottle that only gets used for that.
(sugar free)
(Thank you Jake)

[Bruce2]

I would think plugs thread should be designed to strip before the block threads in the head. true? that's how I'd design things.

The auto makers and the auto parts makers never design things to fail. Why would you want something to fail?

I'm not sure of the plug number. I didn't write it down but remember W6J something like that.

Definitely the wrong plugs. They are two steps to the wrong heat range. The right plugs won't misfire.

[Marc]

"Because of the way threads are cut the suggested practice is to not vary brands to reduce wear of the softer head threads."

I've never seen any manual suggesting this, and never heard any mechanic say this, so I think it's a dubious claim

Perhaps, but it was common dogma back in the day. Supposedly subtle differences in the way that the threads were cut/rolled by different manufacturers was considered reason enough to avoid going back & forth between brands in aluminum heads (e.g. switching from Bosch/Champion/AC/et al without ever settling on a brand). So, there, you've now heard it from a mechanic. I admit to not ever personally verifying that there was anything to this, but it was easy enough to avoid doing, so I never saw any reason to push my luck by testing it...other popular beliefs back then were to avoid Pennzoil & Quaker State oil, or Shell gasoline. Dubious superstitions/myths? Probably... but to this day I won't ever run Pennzoil or QS in an aircooled and I won't gas up at a Shell station unless it's the only one open in town

[sideshow]

It definitely was dogma before the internet, and Champion plugs did look different to me than the then common w145 I found in most free 40hp. How different? hard to say since I lacked any way to measure that kind of subtleness. My pet theory at the time while both were to spec, one start to finish was Metric and the other started SAE the transposed to Metric (tolerances, engrish, thread class something like that).

Or much like the how GL-4 was recommended because that is what was for sale in that era.

Air cooled motorcycle people at that time had the same phobia about using anything other than Ngk or Denso for fear of thread failures (jap dirt bikes)



A random page listing the common plug part numbers; http://vw.zenseeker.net/Ignition-SparkPlugs.htm