how to tell a 454 from a 454 mag

[cor124]

how can i tell the difference between a 454 and a 454 magnum engine and what are the differences.

thank you

 

[cor124]

how can i tell the difference between a 454 and a 454 magnum engine and what are the differences.

thank you

 

[tcob]

you mean before or after you do the autopsy ????after is easy ?the mag has rectangular exhaust ports , the little guy has oval ports . i'm sure vinny can be more specific

 

[Dave's ZT260]

Bring the serial number to a mercury dealer. They can look it up and tell you.

 

[Eriktheviking]

There can be a lot of differences.The 454 (330hp) has a cast crankshaft,lighter duty connecting rods,Smaller ports in the heads as Bob stated,very small runners on the intake manfold.They are a good engine but, you'll have to change everything but the block to make it a reliable high horsepower engine.The Magnum(365hp) has a forged steel crank,heavier duty rods,Larger ported heads,better cam and intake.Makes a good starting point.As I mentioned in a previous thread.If the intake manifold looks almost like its sunk into the block its a 330hp.If the manifold rises up a couple inches then theres a better chance that its a Magnum.

 

[Dave's ZT260]

Check the block code. Front passenger side. XW=7.4, XA=Mag

 

[vinny p.]

I agree with what they said, except for the part about the rectangular exhaust ports. It is the intake ports that are rectangular.

Sorry Bob...

 

[tcob]

vinny , you're on the money ! i need to proofread better