Guest Riviera Swede Posted June 3, 2016 Share Posted June 3, 2016 Hello Is there anyone who has experience using AC45S sparkplugs on a 65: a 401 ''? Buick writes on page 10-41 in the manual '' Where the car is mainly used for low-speed driving the hotter AC45S sparkplug may be used ''. I have read in some forum that someone is not recommended it. It should be mentioned that I only run quiet country road speed and cruising Link to comment Share on other sites More sharing options...
EmTee Posted June 4, 2016 Share Posted June 4, 2016 I'm wondering why you think that you need to go to a hotter plug. Are you fouling the current plugs (44S)? If so, what do the plugs look like? Are they black and sooty (dry carbon), or black and oily (wet)? If the engine is worn and oil fouling is the issue then a hotter plug can help as a temporary measure. If the plugs are carbon fouled (dry) that indicates an air/fuel mix that is too rich. That indicates a carburetor problem. First thing to check is that the choke is functioning properly (fully open when hot). As stated in the manual, the usual case for hotter plugs would be a car that sees a lot of low speed/city use, or prolonged periods of idling. The general condition of the ignition system should be assessed before moving to a different heat range spark plug. Link to comment Share on other sites More sharing options...
RivNut Posted June 4, 2016 Share Posted June 4, 2016 Log into the V8Buick.com site and do a search in "Da' Nailhead" forum for 'spark plugs.' You'll get some numbers that are now being used. Platinum or Iridium plugs that are much better than the older ACDelco's. Bosch, NKG, etc. Link to comment Share on other sites More sharing options...
Jim Cannon Posted June 4, 2016 Share Posted June 4, 2016 (edited) The AC 45S plug will be more prone to pinging when you accelerate. You really don't want to use it unless you have to. The AC 44S plugs are no longer available. I find them NOS at swap meets from time to time. You are better off going with the AC R43S plug. Unless you experience a fouling problem, because this is a cooler plug, this is the way to go. Edited June 6, 2016 by Jim Cannon (see edit history) Link to comment Share on other sites More sharing options...
EmTee Posted June 5, 2016 Share Posted June 5, 2016 Duh, now I understand why the question was asked. I didn't realize that the 44S (or R44S) was no longer available... Link to comment Share on other sites More sharing options...
jframe Posted June 5, 2016 Share Posted June 5, 2016 I crossed the AC 44S over to an Autolite and an NGK number on the OReilly's website that I use for work. Not too sure about Autolite, but I would suspect NGK would be a decent replacement. Any thoughts on this, or is this a Ford vs. Chevy type battle? Link to comment Share on other sites More sharing options...
60FlatTop Posted June 5, 2016 Share Posted June 5, 2016 Over the last few years I have been taking my plugs to the parts store and asking for an NGK that looks like the one I brought. Although I don't buy many my system is working. Through the years, from working on my own Buicks and other owner's GM cars, I amassed a big bag of fouled 44's from collector cars. My choice has always been a 45 heat range. The plugs in my '60 are 45S and been in there for 15 years and about 12,000 miles. Maybe I look at them this year. I think you have to shut it off to pull them. Seems like a shame not to be driving it. Bernie Link to comment Share on other sites More sharing options...
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