: 1970 coupe deville spark plug



marcscaddy75
03-30-11, 09:08 PM
can anyone recomend a specific spark plug for my 70 coupe deville??

cadillac kevin
03-30-11, 10:10 PM
go with AC DELCO plugs. GM motors seem to run best on GM plugs. gap them to factory specs.

intragration
03-31-11, 03:52 AM
I always use Champions, but I would trust AC Delco too. Plain old copper...good in 1970, good today. Goes without saying, if you have HEI or some ignition system other than the factory points, you'd want to go with that particular plug and gap.

cadillac kevin
03-31-11, 02:40 PM
I put champions in my 307. worst plugs ever. they didn't work any better than my 25 year old rusted, burnt, and oil caked plugs.

marcscaddy75
03-31-11, 06:22 PM
thanks, thats what i thought as well.

marcscaddy75
03-31-11, 06:25 PM
i have a petronics points eliminator, what plugs work well with that? also factory gap is .035, do you think it could be different with the petronics? Thanks

intragration
03-31-11, 08:03 PM
I put champions in my 307. worst plugs ever. they didn't work any better than my 25 year old rusted, burnt, and oil caked plugs.

I have put Champion sparkplugs in every car I've owned, including two 307s. I think your statement says more about the 307 than it does about Champion spark plugs. ;)

jayoldschool
03-31-11, 09:59 PM
Nothing but AC Delcos in my GM cars... that's 56 plugs ;)

intragration
04-01-11, 03:34 AM
Who knew that passions ran so high with spark plugs? :) It doesn't seem that the number of plugs owned is a fair gauge of how good a plug is. I owned 70 Champion-fired cylinders as of earlier this year, but who's counting? All my cars run good, I'm sure so do all yours. Champions are good plugs, so are Delcos. All things being equal, new plugs will work better than old plugs. Wrong or mis-gapped plugs will work worse than worn out plugs. 200k mile 140-horsepower 307s in 4500 pound Cadillacs that cause plugs to become oil-caked have bigger problems than even magical spark plugs could cure. In summary, get some new plugs, the copper kind, of the brand that gives you a warm fuzzy, gap them properly, make sure you have more than 10 pounds of cylinder pressure, and throw 'em in. I recommend AGAINST NGK spark plugs. ;)

cadillac kevin
04-01-11, 05:54 PM
my car actually has just under 67k on it. oil was from leaking valve cover gaskets. plugs were gapped to GM specs and installed so the ground strap faces toward the outside of the cylinder. new wires too.

anyways, I also recommend copper plugs. stay away from the fancy schmancy plugs (3 or 4 ground straps, splitfires, etc) they are just a gimmick to get your $ and depending on the car they are put in, can make your car perform worse.

intragration
04-01-11, 07:22 PM
When you said oil-caked, I thought you meant the electrodes. So if you have a low-mile car and you changed the plugs and didn't notice a difference, it's not that surprising. My '70 DeVille has 72k, and I replaced the existing plugs, and I also didn't notice much of a difference. A spark plug isn't going to really add power, unless the old ones are causing a power loss. I agree on the fancy multi-ground strap ones. That seems like it would possibly inhibit flame travel.