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502 BBC


Charger3488

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I have a question my fellow brothas i have a gen 5 502 block stamped 8.2l 502 i called an asked for a oil pan gasket but the tech guy said it was a 454 bored over to a 502 gm did not instal them in everyday vehicles. But from my own research 502 big blocks were not installed in every day vehicles but gm was using them in the 80's and 90's fleet vehicles and army transports. Can anyone confirm this or lend their expertise?

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if that was true...why would the casting on the side say 8.2L???

 

454 blocks can't be bored that big, that's .250 over a 454 bore!!! they did use a GEN V block on the Late 80's and 90's but they aren't the same as a 502 block, they were cast with 7.4L on the side

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Late 454s have 7.4 on the block, 502s like yours have the 8.2 0n the block. 502s were not offered in any vehicle. They are over the counter items. You need a oil pan gasket for a one piece rear main seal big block. Like Sam said it is not a over bored 454. The 502s have siamese cylinder walls to allow the large bore.

GM did supply a lot of 8.1L engines for the military and others uses. The 8.1 is the gen7 big block. Pan rails are different, heads are different, block is taller, and lots of other little things.

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Any Gen V or VI 454/502 pan gasket should fit. I'd either get it from a gm dealer or through Jegs or Summit. A parts store will probably have to look it up by vehicle, which won't work.

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  • 2 weeks later...

Can you send me a link for head gaskets I should use with my 502 to prevent water leaks. I'm looking at fel-pro but I like cometics and their custom gaskets a friend of mines told me that head gaskets play a role in engine compression the smaller the thickness the higher the compression and the thicker it is the lower the compression. I know 502 came with one piston design and with my 110 cc heads the compression will be around 9.7.1 but with the gasket being .25 thick the compression should be around 10.1 or higher like 10.7.1 so ill still be able to run unleaded gas. Can you help me with wat arp kit I should use send me links they'll be so much appreciated part number s will be heaven sent...........thanks

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you also have to take the deck height, and quench height into consideration here too, to get an accurate static compression ratio

 

deck height=how far down the piston is in the cylinder and figure out the CC's

 

head gasket volume CC's

 

piston volume either + or - CC's

 

quench=the distance from the flat part of the top of the piston to the flat part of the cylinder head combustion chamber, and you don't want this less than .035!!! I like mine to be .040-.045

 

then there's the dynamic compression ratio which takes the opening and closing points of your valves into consideration. this is a more accurate way to figure if you can still run pump gas

 

if you don't figure in all of these things, you really don't know where your compression is, but the dynamic compression is what you really want to know to see if you can run pump gas or not

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Are you using the Gen V heads that came with the motor?

 

If you use earlier Mark IV heads, you have to use a specific gasket to ensure the larger water jackets of the Gen V block are covered.

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