GM 8.1 496ci big block

[staledale]

Tried a search but nothing came up, is it down? I'm interested in a 496 truck engine. Is it the same as the older tall truck blocks? I can get one cheap, but no fuel injection. Will the older truck block manifolds fit? I think if the you get the right ports and use a spacer the carb manifolds might work. Now, will the new ports match any of the older manifolds? I saw a marine version with a carb and distributor, but lost the site before getting any info.Might have been a GM high po web site. Any help from you Chevy guru's please............Thanks, Stale

[660Z]

The only thing I know about them is they used Allison transmissions behind them. So i`m betting the bellhousing pattern would be very different. The marine version im guessing the same but not sure.

 

Mark

[Pop N Wood]

Know my neighbors boat uses that motor. Probably doesn't help you any but nice boat.

[staledale]

I did find out it uses the old bolt pattern for the bell housing. It uses drive by wire on the injection (which this doesn't have). If I can get an intake that is cheap enough I'd buy it.

[Michael]

From what I heard, the 496 big block currently installed in heavy-duty Chevy trucks is quite a bit different from the Gen VI BBC, installed since 1996, which in turn is quite different from the “traditional†BBC, the so-called Mark IV, 1965-1991.

 

In the hot-rodding world, by “496†one usually means a 454 or 427 Mark IV block, bored 0.060†over, with a +0.25†stroker crank (so, total stroke is 4.25â€). There never was a stock 496 Mark IV BBC; the largest was 454.

 

The Gen VI BBC differs from the Mark IV principally in one-piece vs. two-piece rear crank seal. The oil gallery and water jacket design is also different. The Gen VI BBC installed in boats is typically a 502, “siamese†(like the 400 small block) with 4.47†bore stock. In recent years it has started to garner aftermarket support, though the Mark IV aftermarket support is still vastly greater. I have never heard of aftermarket parts for the new 496 BBC. From what I recall, it’s back to a smaller bore but longer stroke. The hot rodding community evidently considers it a “truck engineâ€.

 

The Mark IV BBC “truck engine†had a taller deck height (10.20†inches vs. 9.80†inches for the “passenger†big blocks), and is relatively rare. Some hot rodders prefer it for the opportunity to run a stroker crank with a long rod, thus preserving or improving rod to stroke ratio. But the taller deck hampers selection of intake manifold, distributor, pushrods, etc.

 

The new 496 BBC is referred to as a “truck engine†in a pejorative sense – and not to imply that it’s somehow tougher and therefore better suited to high performance use.

[dr_hunt]

The truck blocks are not sought after for HP builds cause they won't accept stroker cranks. They will accept longer rods however. Aftermarket blocks come with either deck height and one even taller than that. The truck block isn't a sought after piece. I have several 427 truck blocks, they are 4 bolt mains, but you can't stick stroker cranks in them without major machine work.