427 or 454: how can you spot the difference?
 

Hi,

I just bought a 1973 K20 4x4 flatbed with a big block. The guy says it's a 427 but not 100% sure. Could be a 454. How can you tell the difference? I can't see the block casting number. It's too close to the firewall.

Thanks,

dyno

Re: 427 or 454: how can you spot the difference?
 

Look at the boss just in front of the right head. Provided the block has never been decked and that number ground off your should see a number that starts with two letters followed by three number followed by two letters. That you can look up and it will tell you the year, size and in some cases the type of car it came out of.

Hope that helps.

Re: 427 or 454: how can you spot the difference?
 

Is that the passenger side?


Thanks...the truck will be delivered in a couple of days so I will look at it then.

Re: 427 or 454: how can you spot the difference?
 

454's are externally balanced . Look at the inside of the harmonic balancer for a cast in counterweight . If it is an automatic, the flexplate will have a weight spot welded on the outer perimeter just inside the ring gear also.
Frank

Re: 427 or 454: how can you spot the difference?
 

Quickest and surest way if it assembled. Jay

Re: 427 or 454: how can you spot the difference?
 

Often the 427 will be a medium duty high deck motor with the 4 ring pistons as these are cheap and available from buses and dump trucks...you can id these with the extra half inch of height above the water pump pads that the cylinder heads are ....also the intake manifold is wider ...