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post #2 of (permalink) Old 12-29-2019, 12:08 AM
Big Dave
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Join Date: Jan 2006
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A couple of problems with this engine. First it is a tall deck marine block. It was made by the Mercruiser division of Mercury Marine as a yacht inboard motor. When Chevy stopped making the BBC on Dec 18 2009 at Tonawanda, NY. Chevy then bought the Mercruiser 8.1 liter engine as a short term substitute for a diesel engine until such time as they introduced the 6.2 litter Isuzu diesel in t's place.

As a tall deck block it will be even taller and wider than a passenger car motor is; so the chances you will be able to close the hood is slim. This is especially true since the EFI intake manifold is for a truck and is taller than the tunnel ram based Arizona Speed EFI system Chevy used on the ZZ502 that usually requires a two inch tall hood scoop.

Mercury licensed the BBC from Chevy but discovered it didn't hold up under marine use (running full power for days, or weeks at time,` moving a large boat around the world). Mercury completely redesigned the motor and unfortunately only the starter motor and the front timing cover interchange with a Gen V or Gen VI big block. Nothing else will fit between the motors. This means you can not change anything. not to improve performance, or to get it to fit under your hood (so expect to cut the front cross-member to clear the truck oil pan). Good news is it uses the same motor mounts so it will drop right into the car (except for the oil pan hitting the front cross-member). You will have to massage the trans tunnel to get a 4L80 to fit and it needs a custom made transmission cross-member but those exist in the aftermarket.

You will have to rework the truck wiring harness or tuck the excess into lumps with wire ties as the wiring and the ECU are programmed for a power curve to emulate a diesel engine in a one ton to a duce and half truck. No cam options to raise the RPM or programmable engine controllers designed for this engine. It can not be converted to a carb and distributor as there isn't a manifold to fit the engine, nor a gear drive for the distributor (uses plug on coil distributorless ignition). There isn't a boss for the fuel pump either so you have to use a high pressure EFI based in tank fuel pump that requires a custom tank.

There are a few more reasons that this engine was never adopted by the aftermarket for hotrodders who rejected it's limitations. But if you read this far you probably realize it is great for a one ton truck but unsuitable for a passenger car. You can turn a standard deck 454 into a 496 far cheaper and with better results. You can still use the 4L80 transmission with a throttle sensor, and an aftermarket Transmission Control Unit (I recommend TCI and have used them frequently). Like I said the tranny will mostly fit (it is based upon a 3L80, which you probably know better as the TH400) except for the added length.

Big Dave
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