Spark plugs NGK OK?

[rich112]

Are NGK BR5HS plugs ok in a '68 1300 single port?

These have resistors in.

Cheers!

[Phil69]

I'd go with a cooler plug say a 6 BR6HS maybe?
To hot and it may start pinging.

[P_Vilefort]

Pinging is not the fault of the plug or is it associated with the heat range of the plug. Pinging is pre-ignition and that is a function of shitty fuel and an incompatible compression ratio; i.e. low grade motor fuel and too high of a compression. For carbureted .engines you can only add premium fuel to stop the pinging or retard the ignition more or less permanently. If the engine has fuel injection and an ECU, the ignition can be retarded automatically to stop the pinging without changing the fuel type. But if it pings frequently a fuel upgrade will help to solve the problem.
Using colder plugs in old air-cooled VW engines usually leads to fouling. Use a hotter plug and check it after a week of running. If it is gray or light brown, leave it alone. If it is black you are having or are beginning to have an oil blow-by problem.

I would look for an equivalent NGK to the original Bosch plug. Get as close to the heat range of the original Bosch. Champion plugs have also been used successfully over many years.

[Piledriver]

Pinging (or more likely preignition, much worse) can be induced by a plug with the wrong (too hot) heat range, usually on a heavily modified engine you run 1 or 2 ranges cooler to mitigate the effects of higher compression or boost.
This is less needed on modern ECUs with high load time enrichment, knock detect etc.

Cooler plugs on a properly running stock engine will not help anything and are more likely to get carboned up, as the correct heat keeps the electrode insulator clean, ideally a nice light brown to cappuchino-ish color.

Traditionally, NGK preferred over std Champion plugs due to NGKs having nickel plated threads that are far less likely to seize in the head.
On higher end Champions, they likely got with the program and do the same as ~all modern cars have aluminum heads.

.. of course, dont forget to use your Milk Of Magnesia on the threads...
(shout out to Jake Raby for providing the ancient gas turbine/jet engine spark plug antisieze tip, I prefer the sugar free with mint flavor)

I basically gave up on Bosch coppers and low end plugs on aircooled engines, NGK or Denso dual iridium or ir/pt tipped plugs can be ordered off ebay/amazon for reasonable prices, and will likely last >the life of a T1 engine unless they get oiled up.

Bosch heat range 7 (std for ACVWs) is equivalent to NGK heat range 6.
From memory Nippondensos heat range 20 is ~same as Bosch 7, chart (hotter or cooler#) runs opposite direction.