Hi! Im new to bbc's and was wondering what parts fit what as far as gen Iv, v, vI go? Im looking at buying some parts and want to build my first bbc(468 or 496...maybe bigger who knows)...Ive found some 502 heads...but what gen they are im not sure and what blocks they fit Im cluless...Im also looking at a set of pistons but they claim they wont fit the gen v or vI blocks...why is this?? Thanks for helping a novice bbc guy out!!
BBC parts whats interchangeable? Gen IV,V,VI?
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The Gen 5/6 crank and flexplate/flywheel is not compatable with Mark IV blocks.
Mark IV heads often leak coolant when used on Gen 5 blocks--but should be OK on Gen 6 blocks. Newer heads work fine on older blocks--use a head gasket that matches the BLOCK.
Gen 5 blocks won't have a fuel pump mount. Some--not many--Gen 6 blocks do have a fuel pump mount.
I have no idea why pistons would not fit a Gen 5/6 block--unless--the dome shape is incompatible with the combustion chamber those engines were equipped with. This would be more common with the tiny-chambered Gen 6 Vortec heads.
The Gen 5/6 crank and flexplate/flywheel is not compatable with Mark IV blocks.
Mark IV heads often leak coolant when used on Gen 5 blocks--but should be OK on Gen 6 blocks. Newer heads work fine on older blocks--use a head gasket that matches the BLOCK.
Gen 5 blocks won't have a fuel pump mount. Some--not many--Gen 6 blocks do have a fuel pump mount.
I have no idea why pistons would not fit a Gen 5/6 block--unless--the dome shape is incompatible with the combustion chamber those engines were equipped with. This would be more common with the tiny-chambered Gen 6 Vortec heads.
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as far as the pistons go theres alot of confusing info out there, i was told by a summit tech guy that the skirt clearance to the crank is different and gen5/6 pistons will not swap to the mark 4 block/crank.(maybe just wanted to sell me new pistons) speed pro says a l2399f "mark 4 only piston" will not work in a gen5 or gen6 block... the tech for je who makes the crate motor pistons for the 502 but wasnt sure if they made the 454 ones, said if the pistons turn out to be je they will deffinatly fit any block...and doesnt see why you would have a problem...with any brand... but his information was not conclusive as they werent sure if they made the 454ho/zz454 pistons... so if it is a skirt clearance problem it should be able to swap one way or the other i will find out for sure soon, as i have a set of gen6 454ho rods and pistons i want to put in a mark 4 block... let you know how it works out...
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I found out first hand that gen IV pistons won't fit a gen V block. The skirts on the gen IV piston are taller than the gen V and hit the crank. You can make the gen IV pistons work with some machine work, just as cheep to buy new pistons. I also believe that the gen IV verses the gen V-VI motors are balanced differently, one is internal and the other is external balance, not sure which one is which. You can use gen IV heads on a gen V block, if you buy this kit from scoggin-dickie and a certain head gasket. There kit consist of 4 pieces of some kinda metal that blocks off one water port and reroutes a steam port. I think the gasket is a fel-pro fel-1017-1. I used this on my gen V without water leaking issues before I went to a new set of Brodix heads. I know the balancer and fly wheel are different between a gen IV and gen V as well.
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