Any 454 experts?

[Orlando87Chevy]

I thought I got lucky today. I bought myself a 454 in excellent condition today for $500. What a steal. When I checked the casting numbers it came up a 1991 454 with a Gen 5 block. I heard that you can't swap the Gen 4 heads to the Gen 5. Is this correct?

[nvrenuf]

You can use Mark IV heads on a V block but you have to use special head gaskets, voodoo and be very careful. It's not a bad motor, you just need to read up on it and learn about the differences.

Does the block use a 1 pc or 2 pc rear main? 2 pc is Mark IV, 1 pc is Mark V or VI.

Btw, Mark V = no mechanical fuel pump boss, electric only.

[Orlando87Chevy]

I looked up the casting number and it was an 1991 4 bolt main. Who makes the special gasket?

[nvrenuf]

A quick Google search yielded this, check out post #4 -

http://www.chevelles.com/forums/showthread.php?t=19073