Big block in a 78
Thread Starter
Melting Slicks
Joined: Oct 2001
Posts: 2,315
Likes: 110
From: Brandon Fl
Big block in a 78
A friend of mine wants to buy my 454 and put it in his 78. What does he need to know to do this? I know 74 was the last year of big blocks in Vettes did they change much since then as far as space wise that would make this harder to do than just an engine swap?
Instructor
Joined: Apr 2006
Posts: 174
Likes: 0
From: Wallaceburg Ontario
I'm considering the same swap for my '79. So far, I've been told the left header may need a kink to clear the steering box and that 3" exhaust may be a tight fit through those holes in the crossmember. Also, the fan shroud may have to be replaced with a shorter one (dual electric fans are also recommended) and it's a good idea to swap the front suspension with big block springs. Solid U-joints (non-greasable) are a must; I keep hearing the name "Spicer" as the recommended brand. A mini starter would probably make life easier for passenger side header clearance. If the car has a/c, ditch it; the more room you can make under the hood, the better. Speaking of the (stock original) hood, I've heard different opionions on whether or not it will clear different carb/intake set-ups for a big block. For my set up (Performer RPM Air Gap a la Holley 770 Street Avenger), I've heard some say a drop base air cleaner might solve the problem while others have said no chance; these replies have been both on and off this forum. Oh yeah; there's also the pricey pulley replacements. To sum it up, the big block swap is certainly feasable, but it'll be tight and require a few alterations. Others on this forum are FAR more knowledgeable on the matter.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Do a search on this. There must be a million posts.
You should not have to modify your headers. Use headers (or manifolds) for a 68-74 BB car and they should fit fine. You will want to add BB springs. Use a BB fan and shroud or electric fans. You should source BB Vette specific pulleys, accessory brackets, and water pump, but I have heard of using more common Chevelle brackets with success-but I haven't done it. Will bolt up to the same transmission bellhousing as a SB. You need the correct flexplate/flywheel for a BB (396/427 is different than 454 due to balancing). Hope that helps.
You should not have to modify your headers. Use headers (or manifolds) for a 68-74 BB car and they should fit fine. You will want to add BB springs. Use a BB fan and shroud or electric fans. You should source BB Vette specific pulleys, accessory brackets, and water pump, but I have heard of using more common Chevelle brackets with success-but I haven't done it. Will bolt up to the same transmission bellhousing as a SB. You need the correct flexplate/flywheel for a BB (396/427 is different than 454 due to balancing). Hope that helps.
Drifting
Joined: Jul 2002
Posts: 1,944
Likes: 20
From: The only Corvettes in Highett Victoria
engine swap
G'day,
You guys are pretty lucky living where you do, with access to plenty of Corvette parts at great prices, unlike us on the other side of the world. As to your request, sure it would be great to drop a more powerful engine into a '78, but think of the parts your friend will have to alter.
Does he reallly want to pull his front end apart to put in heavier springs? Does he really want to change his driveshaft, U-joints, etc?
Radiator, headers, mufflers, tail pipes, etc.
It might end up costing him more than just buying a small block crate engine that will bolt straight in and connect up to all the standard parts. He can buy a 383, or even a 400 or 427 that will be 200 pounds lighter than a big block and make the car run like it's got a big block in it.
Just my $0.02 worth.
Regards from Down Under
aussiejohn
You guys are pretty lucky living where you do, with access to plenty of Corvette parts at great prices, unlike us on the other side of the world. As to your request, sure it would be great to drop a more powerful engine into a '78, but think of the parts your friend will have to alter.
Does he reallly want to pull his front end apart to put in heavier springs? Does he really want to change his driveshaft, U-joints, etc?
Radiator, headers, mufflers, tail pipes, etc.
It might end up costing him more than just buying a small block crate engine that will bolt straight in and connect up to all the standard parts. He can buy a 383, or even a 400 or 427 that will be 200 pounds lighter than a big block and make the car run like it's got a big block in it.
Just my $0.02 worth.
Regards from Down Under
aussiejohn
