Correct spark plugs for 327-250hp

[John F.]

Haven't replaced spark plugs in years. Can you still get ACs? What are your recs for a basic 250hp motor? Nearest auto parts store is O'Riellys or Advanve. I will also be doing a compression check. Have owned the car for about a year and have never touched the plugs.

[John H.]

Re: Correct spark plugs for 327-250hp

John -

AC R45S plugs will work fine - I run them in all my small-blocks; any auto parts store should have them.

[John F.]

Re: Correct spark plugs for 327-250hp

John -

AC R45S plugs will work fine - I run them in all my small-blocks; any auto parts store should have them.

Thanks John!

JF

[John D.]

Re: Correct spark plugs for 327-250hp

John, Your owners manual spells out what spark plugs were used originally. JD

[Duke W.]

Re: Correct spark plugs for 327-250hp

If you want a non-resistor plug (like OE) equivalent to the discontinued AC 45, the Denso W14-U and NGK B4 are it for SBs with gasket seat plugs.

For all OE vintage engines - both SB and BB regardless of power rating - a heat range equivalent to AC "5" is best to avoid premature fouling, and they won't overheat in sustained high speed freeway cruising.

If you run race track hot lap events, install a plug equivalent to AC heat range "3" for SBs and "2" for BBs.

Duke

[John F.]

Re: Correct spark plugs for 327-250hp

If you want a non-resistor plug (like OE) equivalent to the discontinued AC 45, the Denso W14-U and NGK B4 are it for SBs with gasket seat plugs.

For all OE vintage engines - both SB and BB regardless of power rating - a heat range equivalent to AC "5" is best to avoid premature fouling, and they won't overheat in sustained high speed freeway cruising.

If you run race track hot lap events, install a plug equivalent to AC heat range "3" for SBs and "2" for BBs.

Duke

I just put in a new set of R 45S from Advance and all is working fine.