Spark plug options

[snowwolf]

I took one of my plugs to europarts to get an equivalent to my ACDelco 12571165/41-104 they came up with the Bosch HR6DPP33V as you can see in the photo the ceramic part is a lot different, I would normally just order the ACDelco from MF but needed some quick.

I can't seem to find anything on the internet if these are the equivalent for the ACDelco's

[stevieturbo]

Top one may potentially be a colder heat range.

Really wouldnt worry too much about it...and would just fit some normal plugs if it was my car, none of that silly tapered seat nonsense.
That's a strangely US thing.

[snowwolf]

Do they not have to be a tapered seal ? thought copper gasket ones were for a flat face seal, forgot to meantion what one was which, the lower sooty one is the ACDelco which the fit in the SC LS9 the upper one is the Bosch

[007 VXR]

Roger put ls9 plugs in mine

[stevieturbo]

snowwolf said:

Do they not have to be a tapered seal ? thought copper gasket ones were for a flat face seal, forgot to meantion what one was which, the lower sooty one is the ACDelco which the fit in the SC LS9 the upper one is the Bosch

Ive never used tapered seat in any LS heads I've used ( other than factory plugs and some TR6 right when it was a bog standard LS1 many many years ago )

From factory heads, Edelbrock and Trickflow.

All the heads Ive used have a flat face for the washer to seal on, and plug length in the chamber is identical to taper seats anyway.

And very very few UK/Euro spec cars use taper seat, so they arent so readily available.
So it's just easier to use normal plugs. Plus they're less likely to get stuck in the head.