What is the easiest way to tell the difference beteween a 502 and 454 when in the boat. Looking at a boat that is supposed to have a 502 but not sure and want to check it out tonight

Casting numbers on the back of the block is the best way to tell..

also i dint know if they all had this but mine have a 8.2 casted on the side of the block next to the freeze plugs.

Do you know what the casting number should be for a 92

There should also be a metal tag attached to the block with the serial number on it.

454 has 7.4 on the side of block
502 has 8.2 on it !!!!!

But maybe its a 454 stroked to a 502 ?!

Where might that tag be located

On the back by the bellhousing but usually doesnt survive that long. Is a mercruiser engine or a custom. A merc motor will have it on it or at least you can look it up. Other than that you will have to pull the casting number and look it up.

i may be wrong but i thought 502,s had no provision for a mechancal fuel pump,no casting for it on the block.

Gen 4 502's have a mechanical fuel pump on the block. Gen 4 502's also have a chevy bowtie on one side of the block....hense, a Bowtie block! Gen 5 and 6 blocks need to run electric fuel pump or off the sea pump.

[QUOTE=kreed;3189572]Gen 4 502's have a mechanical fuel pump on the block. Gen 4 502's also have a chevy bowtie on one side of the block....hense, a Bowtie block! Gen 5 and 6 blocks need to run electric fuel pump or off the sea pump.[/QUOTE

Gen 5 454/7.4 also do not have the casting for block mounted fuel pump. At least my 7.4 doesn't.