Spark Plugs

[GCAMINO]

What plugs are the best for my mild 62 409 with 10 to 1 pistons , a mild hydraulic cam , and 2 carter four barrels. The carbs have been restored to what I think are factory specs. Seems to run very rich.

 

[rstreet]

Hot range plugs
Robert

 

[rstreet]

44 or 45 range. I used 45’s in my 2-4 car ran great

 

[heddrik]

Do you use old style plugs or the new split fires, or whatever they call them?

 

[Don Jacks]

I've used the AC Rapidfire plugs with great results.The Split fire and other "trick" shit was just that.

 

[La Hot Rods]

I like NGK's for the race car, they are easier to read. Can't think of the part number off hand.

 

[rstreet]

Do you use old style plugs or the new split fires, or whatever they call them?

Old school style! R45XLS
Robert

 

[chuckl]

 

[boxerdog]

I like the NGKs these days, but I have used Accel shorties, Autolites, Delphis, MSDs and ACs also.

 

[IMBVSUR?]

I've used the AC Rapidfire plugs with great results.The Split fire and other "trick" shit was just that.

Like most here, I have used many different brands over the years. I too don't care for plugs or tricks that hide ignition or tuning issues. I had not heard of the AC Rapidfire plugs Don. I looked and there seems to be a standard and a platinum? Why do you like them? What kind of motors have you used them in? 09's? Platinum or standard, or did I read it wrong.

 

[Don Jacks]

I've used them in small blocks.Why,because I can trust the heat range and because they last really well.I've always used the standard as opposed to platinum.AC Rapid fire's have been around since the 90's.

 

[wristpin]

Did the origional rich condition go away with plug change or is fine tuning of carbs and ignition curve required?

 

[chuckl]

For whatever reason (heat buildup/conduction/resistance) Bosch plugs will not work in my mild build 348 (10.5:1, 0950 cam and 333 heads). I've tried them all and Bosch simply do not work well. I have no idea why. The best performance is from R45XLS. I don't think having a rich exhaust mixture is the fault of the plugs. A plug's heat range can't do much to compensate for a rich mixture coming from the carbs/intake. Just my $.02 worth.

 

[Don Jacks]

I've never seen Bosch Platinum plugs work and hold up in any thing automotive.They're worse than Champion plugs and that's saying something.

 

[boxerdog]

I think I have Champions in some of my yard equipment. And I agree, Bosch NFG.

 

[heddrik]

I used autolite in the old days, even on chevies.

 

[Jim Sullivan]

Autolite has been my plug of choice for years. I stopped using AC because the electrodes started looking pretty bad when compared to other plugs. They must have cheapened there manufacturing processes? Never had any issues with Autolite. I did just switch over to NGK in my 409, after reading some positive posts here on the site. Too early to tell how they will do, no where to drive it to yet.

 

[GCAMINO]

Thanks to all for your input. I've had good luck with NGK's in the past. The carbs are original carters , 3661 , and2. restored to original. That being said , it's possible the the original jetting for a 409 horsepower engine might be too rich for the 10:1 pistons and milder hydraulic cam. I put a new set of NGK's , drove for ten minutes. The plugs were turning black. Any suggestions on some jetting changes I might make. I've re-built a number of carbs, but never got into the fine art of jetting.

 

[Don Jacks]

What are you running for ignition on that engine?

 

[Jim Sullivan]

I think you'll have to determine different driving conditions in which the engine is running rich. Is the car loading up at idle, cruise or wide open throttle or all conditions? Then you can start to determine what adjustments might be necessary.