Got an 83 HO garage find sitting for about 30 years. Im going thru each system and replacing everything as I go. The sticker on the shroud says gap is .080. I read a few posts and guys said they run kinda crummy at that gap and Ive seen recommendations of .060 and .040. I do have the correct NOS spark plugs. Is there a consensus on the gap or go with factory and dont change a thing. Thanks

 

I'd run at 0.060, it would be less stress on the ignition coil and probably reduce burning of the cap and rotor contacts. There were TSB's back in the day to reduce the gap which could cause starting problems in extremely cold conditions.

 

045 is plenty

 

If you're going to run .045 or .060 it would be best to get plugs made for the gap you will use vs. gapping an .080 plug at the tighter spec.

 

So instead of the R45SX what plugs if I use the .06 or .04?

 

I want to say 46s are hotter, so shorter hotter spark instead of colder with a Grand Canyon. NGKs are reverse- higher number is colder.

 

I think an R45S would be good at .045. I'm not sure about taking it to .060 though, you could end up with the electrodes not close to parallel.

 

Keep in mind that the monster plug gaps were used to allow these cars to meet EPA requirements to be able to meet emissions standards after 50,000 miles without a tune up. The huge gap prevents the plugs from shorting out even with crud built up on the electrodes. The whole reason why GM went to the High Energy Ignition (HEI) system was to provide enough voltage to fire those crusty plugs. If you actually maintain your car, you don't need nor want the 0.080 gap.

 

I’ve been running HEI’s for decades on big blocks. I’m not a real engine specialist, but have retrofitted Progression Ignition HEI’s to both my big cars.

If I have it right, a narrower gap tends to run smoother at idle, whereas a wider gap tends to yield more power. Just to understand the trade off.

I run both my big blocks at .0.045” gap and that seems to provide a nice balance of idle smoothness and power.

If you really want to beef the h*ll out of your ignition, sure, try .060. But .080, however factory it might be is madness to me.

Do what you want, but if it were me I’d play around with gaps between 0.030, 0.045 and 0.060 and not beyond.

Having said that, if you run and like a bigger gap, please report in here at CO

Cheers
Chris

 

I think I recall R45s is .045, R46sx is .080, R46sz is .060. "46" is one heat range higher than "45". I haven't been able to find the x or z lately. I now use R45S in my 71 350 as I now have pertronix in standard distributor. Seems fine.

 

It will be a bit before I fire it up as I still need to drop the tank and clean out the old fuel. I set gaps at .060. Figured it’s kinda the middle. 🤷

 

If I'm reading this right, I can go with R45s plugs for my Olds 260 F motor in my 1979 Calais and my 1979 350 R motor in my 79 Hurst Olds, and use a gap of .045, instead of the R46sz's at .060 I currently use for both motors? I would really like to try this as I've always thought my rotors and/or ignition modules were burning up too quickly. This sounds like a great idea. These are both low power motors, so I probably not feel any measurable amount of sluggishness at the high end.