Spark plugs

[STDog]

Rebuild a 1970 472. Stock ignition and carb.
And recomendations on plugs?

I though about trying the platinum, like the Bosch Platinum2, but can not find a direct cross.

Stock is Delco R44XLS (.035" gap), Autolite 66.

I did see a cross for a '76 500, but it used HEI, and a 0.060" gap originally.

So how do I find a good match? What are the trade offs?

[cadzu]

imo i would stick with the ac-delcos i've never had any problems with them.
plus you'll get a better burn with a cooper plug.platinum runs cooler that's why they last longer but dont burn as good.

[Gorf]

I have had really good luck with Bosch platinums. I have also run split-fires in years past. Don't seem to see them much anymore. They really paid off with high-fire ignition systems like MSD.

[cadillac512]

I have R44XLS in the '70 472 in the malibu and in both 500's I race the T with. They have been perfect.
Terry

[cj2/500]

I always run ac plugs in my cads. In fact, I run factory plugs in everything even remotely stock. not as important on older cars as it is newer ones though. Wanna pi** off a 4.9 caddy? :evil: try a set of multiple electrode platinum plugs :!: What a p.i.t.a. to do a set of those twice :!: :oops:

[Caddycarlo]

if you are going to stay with the points ignition you need to stay away from platinum plugs as they are harder to fire and can cause arcing of the ponts and short point and condensor life ...... if you are looking for a better spark you can add a msd box or go to hei or some other electronic ignition ........ also non carbon core wires ......

[rickpilgrim]

The expensive irridium AC plugs work great for us, you can flood them and they still work. They don't take any extra voltage either

[Schurkey]

Rebuild a 1970 472. Stock ignition and carb.
And recomendations on plugs?

I though about trying the platinum, like the Bosch Platinum2, but can not find a direct cross.
Platinum plugs with multiple ground straps are a marketing gimmick. It's a way to justify the insane purchase price. Stay away.

Stock is Delco R44XLS (.035" gap),
There ya go. I'd consider opening the gap to .040; but either way it'll work fine.

Autolite 66.
I used to love Autolite plugs. Now they've moved production to Communist China, so I avoid them like AIDS. I did find some leftover non-Chinese-shit plugs; and I bought all I could find in the part numbers I use.

I did see a cross for a '76 500, but it used HEI, and a 0.060" gap originally.
Too wide for performance use. Burns up the carbon button in the HEI distributor cap even in stock trim; if you drive hard.

[rickpilgrim]

When GM brought out HEI they specified the plug gap at .060. a few yrs later they (GM) started specified setting the plug gap at .045 and a TSB
to the Chevy dealership I worked at recommended that all previous yr cars be changed to that (.045) gap also when HEI equipped.

[whitfimb]

I avoid the platnium plugs. They are designed for the 70k - 100k miles tune up (endurance) not premium performance.

http://www.fueleconomy-blog.com/spark-plugs-for-fuel-economy/ (http://www.fueleconomy-blog.com/spark-plugs-for-fuel-economy/)

The most common materials a spark plug is made out of would be copper or platinum. Platinum plugs have gotten a lot of press and marketing in the last decade or so. One of the major marketing messages is that platinum plugs increase fuel economy.

The truth is that copper actually conducts electricity better than platinum and produces a stronger spark (and thus a better burn). However copper doesn’t last as long as platinum, which is how they can make the false statement. If left unchanged over 20-30K miles then platinum plugs can produce better fuel economy.

The moral of the story is that if you can replace the plugs more often stick with copper. They will produce better fuel economy and cost less than platinum plugs.

Also:

Platinum spark plugs are not recommended due to the fact that the tip surfaces of a platinum spark plug is not large enough to make a good conductor in a non perfect (Read older vehicle's) environment. Standard type spark plugs provide plenty of surface area for the spark to conduct under such conditions. Therefore a conventional spark plug is recommended because it has a larger surface area that will allow the spark to occur.

In a racing environment, there are generally no emissions standards and an excessive amount of fuel present. This environment can cause spark blowout if you are not using the appropriate setup. Same can be applied to high miles engines that are burning / using oil.

[79fleetwood]

i really like NGK G power platinum plugs. have them in my 70 427 with a HEI. raced it all summer and they look like new. its in a full trim 79 fleetwood that runs mid 8s in the 1/8 th mile.

[STDog]

Wow, dug up an old thread.

I honestly don't remember what I ended up going with now. Just a copper plug though, as everything pointed to the other metals not being good choices for a points ignition.

[trvlr480]

Hello ST,

I've been using AC Rapid Fires in mine for a real long time and they work great. They may be overkill for a stock ignition but with elctronic they work like a charm. I can't see why they wouldn't work for a stock ignition as well.

I asked around to see if any of the higher end Bosch plugs were made for the 472 but they weren't at the time so I just stayed with the Rapid Fires. As far as I know, Bosch doesn't make any of their higher end plugs for the Cads but that may not be the case now.

Yes, the Rapid Fires cost a lot more but I noticed a slight difference in throttle response when I switched to them years ago over the stock plugs.

I put in a new set about 8000 miles ago and haven't even pulled them for a check since then. It will probably be another 8000 before I look at them.

[trvlr480]

When I went to this thread all that showed up were the first two posts. It looks like the problem has been solved.

[STDog]

As far as I know, Bosch doesn't make any of their higher end plugs for the Cads but that may not be the case now.



Which Bosch pugs are you thinking of?
http://www.rockauto.com/catalog/x,carcode,1025378,parttype,7212

BOSCH Part # 7911 {SUPER PLUS}
BOSCH Part # 4220 {Platinum #WR9DP}
BOSCH Part # 4020 {PLATINUM PLUS #4220, WR9DP}

I'm sure a suitable iridium plug exists too, it's just not in the application charts.
For example, 4507 (WGR9DQI ) listed for the '84 Fleetwood w/ 6.0L
http://www.boschsparkplugs.net/more_info.asp?AAIA=&pid=27505

Or the 4506 (WGR8DQI) for the '84 Blazer w/ 1.9L for a hotter plug
http://www.boschsparkplugs.net/more_info.asp?AAIA=&pid=27504

[trvlr480]

Which Bosch pugs are you thinking of?
http://www.rockauto.com/catalog/x,carcode,1025378,parttype,7212

BOSCH Part # 7911 {SUPER PLUS}
BOSCH Part # 4220 {Platinum #WR9DP}
BOSCH Part # 4020 {PLATINUM PLUS #4220, WR9DP}

I'm sure a suitable iridium plug exists too, it's just not in the application charts.
For example, 4507 (WGR9DQI ) listed for the '84 Fleetwood w/ 6.0L
http://www.boschsparkplugs.net/more_info.asp?AAIA=&pid=27505

Or the 4506 (WGR8DQI) for the '84 Blazer w/ 1.9L for a hotter plug
http://www.boschsparkplugs.net/more_info.asp?AAIA=&pid=27504

I was referring to the Bosch Platinum's. As I said in my post the situation has probably changed but over five years ago I was asking at NAPA, Autozone etc. if they could get any Bosch plugs for the '73 472 and they said no.

I've been using the Rapid Fires for a very long time and haven't checked into it in over five years. Maybe longer. It's possible that I just ran into people who didn't know what they were doing and since the Rapid Fires have performed nicely I quit looking into it.

[STDog]

I was referring to the Bosch Platinum's. As I said in my post the situation has probably changed but over five years ago I was asking at NAPA, Autozone etc. if they could get any Bosch plugs for the '73 472 and they said no.


They were just being lazy then. Bosh plugs were listed for the 472 when I got the car in 2000. I just couldn't find the Platnium2 line (dual ground electrodes) in 2005 when I started this thread.



And I'm not spending $5+ for a spark plug now. I don't have cash to waste like that.

[trvlr480]

That's good news. I may give Bosch a try the next time I replace my plugs. Some of these guy's at the parts stores ARE lazy. I asked around when the platinums first came out and for acouple of years after that and I was always told they didn't make them for the 472.

As far as the $5 bucks for a spark plug I know what you mean with cash being tight. The Rapid Fires I have in there now will probably be in there for some time to come. I'll just clean them from time to time. Supposedly they are good for a very long time but I've never pushed the issue before. I may have to see just how long that is this time.

[1975_Fleetwood_Limo]

I prefer to use the regular AC plugs in My GM engines