Best spark plugs?

[78 GMC Jimmy]

SBC 400
Unknown cam
Aluminum intake
1406 carb
Headers

So whats the best spark plugs? Standard OEM? Fancy iridium plugs? G3 plugs?

I'm looking to replace mine due to misfire and pinging. So what plug would be best for me?

 

[Wes Harden]

R43ts, or equivalent in ngk, or ngk ur6ix which is iridium

Edit r43ts is small 5/8 hex plug if you need the old 13/16 then r43s

 

[78 GMC Jimmy]

Not having much luck finding those plugs at a reasonable price.

Would these be OK?

Amazon.com

Or even better - these:

Amazon.com

 

[Wes Harden]

the g power are cooler, than the ur4, and the ur5gp are platinum plug so will last a bit longer than a nickle alloy plug. 400 sbc run a little hot so a cooler plug is better, esp if it has improved compression.

 

[78 GMC Jimmy]

the g power are cooler, than the ur4, and the ur5gp are platinum plug so will last a bit longer than a nickle alloy plug. 400 sbc run a little hot so a cooler plug is better, esp if it has improved compression.

I'm still battling a "pinging" problem. Pings on start when hot, pings under 30% throttle in second gear WOT at 30 MPH. Tried 3 different carbs, tried 2 different distributors, tried 1000 distributor rotation positions, tried different octane, tried octane additives, tired different thermostats, tried removing the thermostat.

Now I'm looking at the de-carbon procedure on the cylinders and different spark plugs. So what ever plugs promote Non-detonation, is what I would pick.

Every time I drive it, it pings and kicks back on start up (after its warmed up). And I can always get it to pink under load if I want to. Its a brief ping at a certain RPM under a certain load when WOT, always in the lower PRM range.

 

[Wes Harden]

a r43ts would be a ur6 in ngk I would try a 6.

 

[Fastereddie]

Isnt r45 the standard heat range?

 

[Fastereddie]

And if its hard to start hot, its too adavanced

 

[Wes Harden]

low compression smoggers are r45

 

[78 GMC Jimmy]

And if its hard to start hot, its too adavanced

If we eliminate timing, what else could cause this?

 

[Fastereddie]

Has it always done this?

 

[Blue85]

It seems we should take this discussion back to https://ck5.com/forums/threads/pre-ignition-starting-problem-ripping-hair-out.349339/

 

[78 GMC Jimmy]

Side note: I replaced the entire distributor - no help.

This is why I'm thinking spark plugs / de-carbon the cylinders.