427 vs 454

[Don M.]

Guys since both the 427 and the 454 use the same engine casting #, is there an easy way to tell visually a 454 from a 427?? I don't know how. Don

[Joe L.]

Re: 427 vs 454

Guys since both the 427 and the 454 use the same engine casting #, is there an easy way to tell visually a 454 from a 427?? I don't know how. Don

Don------


The only way to know, for sure, with an engine installed in the car is to try to check rear of the harmonic balancer to see if it's counterweighted. If it is, the engine is a 454.

Any block originally built as a 454 can be converted to 427 by changing the crank and pistons. Most later 427 blocks can be converted to 454 by changing crank and pistons. Some earlier 427 blocks can be converted to 454 by the aforementioned and grinding out certain areas on the lower crankcase.

454's use different harmonic balancers and flywheels than 427's.

[Ray K.]

Re: 427 vs 454

Don,

As Joe has referenced the best option is the harmonic balancer and flywheel. The 454 engines were externally balanced by counterweights on the these 2 components. The 427 engines were internally balanced. If you can see ( with a mirror ) you might be able to determine if the back side of the balancer has this weight provision or not Checking the flywheel requires a little more effort as the flywheel underpan must be removed to see the back side of the flywheel but this would give you good visual access to inspect for the weighted area.

Ray

[Mark E.]

Re: 427 vs 454

Do you want to know the current displacement? Or the original application for the block?

Joe and Ray addressed the first. The only way I know to determine the latter (there may be other ways) is the engine suffix code if the block is stamped.

Of course, there's always the sticker on the air cleaner. :-)

[Don M.]

Re: 427 vs 454

Thanks guys, I will check the harmonic balancer in the morning.

[Joe L.]

Re: 427 vs 454

Thanks guys, I will check the harmonic balancer in the morning.

Don------


This is what you're looking for.

[Don M.]

Re: 427 vs 454

Thanks Joe, you are always a big help. Don

[Jeff B.]

Re: 427 vs 454

Guys since both the 427 and the 454 use the same engine casting #, is there an easy way to tell visually a 454 from a 427?? I don't know how. Don

427 engines and 454 engines do not share the same casting number. That, in itself, should ID whether the engine was born as a 427 or a 454.

[Joe L.]

Re: 427 vs 454

427 engines and 454 engines do not share the same casting number. That, in itself, should ID whether the engine was born as a 427 or a 454.

Jeff------

The GM #3963512 block was used for both 427 and 454 applications during the 1969-70 period. Otherwise, post factory, the 427 and 454 blocks can be interchanged as I described above.

[Dick W.]

Re: 427 vs 454

Don------




Any block originally built as a 454 can be converted to 427 by changing the crank and pistons. Most later 427 blocks can be converted to 454 by changing crank and pistons. Some earlier 427 blocks can be converted to 454 by the aforementioned and grinding out certain areas on the lower crankcase.

454's use different harmonic balancers and flywheels than 427's.

As a side note, the early 512 blocks were not ground for crank counterweight clearance

[Jeff B.]

Re: 427 vs 454

Joe:
Thanks for the info. Never to old to learn.

[Ray K.]

Re: 427 vs 454

All,

The #3963512 block also shows application for 1971 production.

Ray

[Tom P.]

Re: 427 vs 454

And just to throw a twist into this discussion, just for the heck of it. If someone has rebuilt a 427 and stroked it with a 454 crank (or aftermarket 4.25in crank)---------------AND THEN HAD IT INTERNALLY BALANCED---------------the same 427 balancer and flywheel can be used. Thus, checking the balancer/flywheel for additional weight and determining whether it is a 427 or 454 is invalid.
My philosophy is "More cubes is still not enough". Therefore, I feel a 427 or 454 deserves to become a 496. Too much power and torque is just right!

[Kenneth B.]

Re: 427 vs 454

Don------


The only way to know, for sure, with an engine installed in the car is to try to check rear of the harmonic balancer to see if it's counterweighted. If it is, the engine is a 454.

Any block originally built as a 454 can be converted to 427 by changing the crank and pistons. Most later 427 blocks can be converted to 454 by changing crank and pistons. Some earlier 427 blocks can be converted to 454 by the aforementioned and grinding out certain areas on the lower crankcase.

454's use different harmonic balancers and flywheels than 427's.

Don't the 454's use a deeper oil pan also?

[Joe L.]

Re: 427 vs 454

Don't the 454's use a deeper oil pan also?

Kenneth------



No, the oil pan is not deeper. However, the internal baffle on the oil pan is set a little deeper to allow clearance for the crank.