Best Spark Plugs for Big Block 454 Chevy

A little more than 50 years after its inception, Chevy’s big block 454 is still tremendously popular among hot rodders. If that’s not a testament to its performance, what is?

There’s one funny thing about the 454’s spark plug options, though. Usually, I’d wholeheartedly vouch for NGK as the leader in most engine applications.

Things are different here. The best option would be either ACDelco or Autolite, as the good ol’ big block responds best to their plugs. Namely:

I’ll discuss this later on, but the different numbers (43, 44, 45) in the ACDelco spark plugs refer to their heat range. The 43s are the coldest, while the 45s are the hottest.

As for the Autolite option, this one’s the correct for your 454 big block:

For casual city driving, you’d want something warmer. If you’re on the race track or plan on speed-fueled highway action, go for a colder spark plug.

Let’s kick things off with a bit of historical context.

At their inception, stock Chevy big block engines used ACDelco’s 43N spark plug variety. It was tailored to fit and perform well with the standardized 454 gasket design. You can’t find 43N (or R43N) plugs anymore, though – maybe at an online auction, if lucky.

The thing is, gasketed plugs were a pain. They’d choke during cold starts in winter, the engines would stall, etc. GM decided to switch to tapered seat plugs at the end of the 60s to address those issues.

Here’s where the ACDelco R4xT/R4xTS lineup comes.

These plugs are direct OEM fit for the tapered seats on the updated GM design. The ‘T’ stands for tapered seat.

If you wonder what’s the difference between an R43TS and an R43T…It’s the extended tip on the ‘S’ plugs. The extended core tip is overall better for street Chevy 454 engines.

You can still use ‘S’ spark plugs on a standard/milder big block. In fact, this type runs great with headers, too.

So when should you get the extended tips?

In most cases, really. They perform better and above all, they also last longer compared to the older plug design (recessed tips).

You don’t need to fuss with platinum or iridium spark plugs, either. The 454 Big Block runs most optimally on standard copper plugs.

Platinum would be the worst out of the three, actually. It’s a poor conductor that holds heat and on a racing 454 engine, you will see a lot of strong pinging.

Here’s a quick look at ACDelco and Autolite, the best spark plug brands for Chevy 454 in my opinion:

➥➥ ACDelco R4xTS series

All of the OEM-fit ACDelco spark plugs feature a copper core. This helps with better conductivity and keeps them intact for longer.

ACDelco’s also has a nickel-chrome alloy coating which protects the core electrode from corroding over time.

Potential misfires and the dreaded flash-overs are taken care of by the ribbed suppressor seal. It improves the plugs’ resistance extension and minimizes the risk of faulty performance.

➥➥ Autolite 26 series

This is another copper core spark plug, pretty much a direct alternative to ACDelco or Chevy 454 engine OEM parts.

You have a ribbed insulator here too with the exact same mission to prevent misfires or flash-overs.

Compared to the ACDelco, the Autolite spark plugs also feature a better resistor focused on clearing out any radio frequency interferences.

With a cold-formed steel shell and intricate thread design, the Autolite 26 ensures long-lasting, durable, and conductive operation.

Obviously, it would depend on how you configured your engine.

Generally, Chevy big block 454 engines run their spark plugs gapped between .032 to .045 in the majority of applications. This is a slight deviation from the gap found in brotherly setups like the 396.

If you have an STD ignition, most often you want to run your 454 engine between .032 to .035.

At higher voltages when running an HEI big block, you want to go higher. In most cases, your spark plugs should be gapped at .045.

There are also some custom setups that go beyond this range. I can’t comment on these; I’m giving you the most common scenario for big blocks. Remember to keep your spark plug wires up-to-date too.

These 454 spark plug wires offer great durability and heat conductivity for their price.

As I noted at the beginning of my post, you need to make a decision whether you’ll go hot or cold with your big block 454 spark plugs.

The general rule of thumb is to run hotter plugs in colder engines. Vice versa, you’d better put some cold spark plugs in hotter-running engines.

Essentially, this means that if you’re drag racing or conquering the tracks, you’d need ACDelco R43TS or equivalent. High-performance 454 big blocks generate a ton of heat, so you need to counterbalance it with colder plugs.

Related: for strip action, check out my guide to Chevy 454 carbs for higher RPM, and hot-on-the-action performance. An extra factor is also carefully selecting the proper starter for your big block.

Working together, these components will provide the oomph! you want to see in your 454 engine. If you’re seeking higher performance, that is!

For casual cruising around town or lower RPM driving, spark plugs in the 45 range would fit your 454 engine the best.

In this case, running too cold of a spark plug might simply lead to your engine not starting at all. Especially in colder months of the year.

Part of my fascination with the Chevy 454 involves the iconic muscle cars from the 70s that ran on it. I’m sure this holds true for both you and other car enthusiasts.

Here are the staple Chevy models from big block’s heyday:

• 1970-1975 Chevrolet Chevelle
• 1970-1975 Chevy Monte Carlo
• 1971-1972 GMC Sprint – too brisk of an appearance, sadly
• 1970-1974 Chevrolet Corvette – my dream car as a kid
• 1970-1975 Chevrolet El Camino – the one I like the least, but still an amazing car

What’s yours? I’ve seen a lot of well-kept Chevelles, though the one car that made a tremendous impression on me was a neatly modded Caprice a few years ago.

Let me know your favorite 70s muscle car running on this roaring engine beast, the Chevy 454 big block.

For other entries related to classic Chevy trivia, check my guide to older Chevy engine carbs. If you’re keen on something more modern, I have a guide on contemporary Chevy truck stabilizers.

If you run a small block engine-based project alongside your work on the 454, you might have wondered about cylinder head numbers. I’ve written on the 799/243 heads you can see on LS2/LS6 engines, a topic that’s filled with inconsistencies.

In the mean time, cheers and happy big blockin’!