Back in 1970, Keith Diabo’s father came home with a new Buick Riviera GS and sparked what would be Keith’s calling in life – restoring classic muscle cars and engines. Not to be outdone by his dad, it wasn’t long before Keith got his first 1970 Buick GS Stage 1 in 1979, and the rest, as they say, is history.
Along with Duane and Corey Diabo, Keith has been running Gran Sport Autobody in Kahnawake, Quebec, Canada since 1985. The shop specializes in custom muscle car restoration and engine work with a focus on Buick performance cars and engines.
Recently, Gran Sport Autobody had two customers request aluminum Buick big block engines. The first was a 530 cid block for a white GSX that had been in the shop more than 20 years before.
“We first built the car in 1996, with a Buick big block,” says Diabo. “This car has since changed hands a couple of times. Today, it has ended up with Bob Ortolani, who has become a really good customer and a good friend who lives in Syracuse, New York. The car is a street strip car.”
That 530 cid aluminum Buick engine puts out well over 900hp. The second engine Gran Sport Autobody is building is for a blue GS owned by Ken Montour and is also a 530 cid block. However, Keith expects it to be a little beefier than its sister engine.
“Our goal with the latest 530 cid engine is to try and meet or exceed the 1,000hp mark,” Keith says. “It’s a really special build as far as Buick goes because it’s getting built with all top shelf components for the crankshaft, pistons and rods. It’s a 440 stroker engine and there is a whole lot of R&D, flow testing and performance work that’s going into the TA Performance Stage 2 Eliminator cylinder heads.”
The newer aluminum engine is a TA Performance aluminum block and it’s a relatively new piece that’s only been out for several years. For that reason, Keith says there really isn’t a textbook build established with the block yet.
“We’ve been collaborating with TA and made some discoveries through R&D and passing information back and forth,” he says. Some of the people building these blocks who aren’t familiar with them are running into problems and having failures with them – not because there’s anything particularly wrong with the block, they just don’t know how to build them yet.”
Fortunately, Gran Sport Autobody has seen a lot of success so far with these engines.
“We haven’t run into any failures or problems,” Diabo says. “We discovered a few things along the way. The block isn’t a plug-and-play block. There has to be some additional work done to the block. You have to square the decks. You have to line hone the block. You have to check for some clearances for the lifters and intake and things like that.”
These Buick aluminum blocks are a lot more expensive to build than the run-of-the-mill big block Chevy or Mopar. Right out of the gate the block is $6,000 and you have to invest at least another $1,000 or so to do additional work to it, Diabo says.
“You have to be pretty careful with clearances because that’s one of the problems other engine builders aren’t familiar with since the aluminum block will expand with heat,” Diabo says. “No one really knew how much these blocks expand or what clearances they were running. We do something interesting where we heat up the block to operating temperature and we’re able to measure how much the block expanded. Just from reaching operating temperature the deck increased .010” and the clearances on the crankshaft increase a couple of thousands as well. We thought of the expansion rate of the block and we took the extra time and trouble to measure it.”
In addition to the added difficulty of the aluminum block expanding, the decision to use TA Performance’s Stage 2 Street Eliminator heads has also made the build special and more noteworthy that the engine will put out around 1,000hp.
“The power levels we are reaching are not as easy to get with these Stage 2 Street Eliminator heads,” he says. “Most folks building these engines are using the Stage 3 and Stage 4 ‘race’ heads.”
As mentioned earlier, this 530cc aluminum Buick engine got the custom parts treatment because there really isn’t another option. It features a Crower crankshaft, GRP aluminum connecting rods, and Diamond pistons and rings.
“There really isn’t a kit available,” Diabo says. “It’s really very unique and very different from building a big block Chevy or something where you can buy the block and you can buy the whole kit with the rotating assembly and everything. The Buick is not like that at all. It takes a few months just to get the crankshaft.”
Diabo says there are rocker arms available from the manufacturer, but they can’t handle the lifts and the spring sizes needed on the cylinder head. So the build also involves getting custom machine work and custom rockers from Jesel to complete the assembly. Another unique aspect of this engine is the custom built camshaft that is made right here at Gran Sport Autobody.
“We design our own camshafts,” he says. “My brother Duane is very involved with a lot of the design work and engine builds. We have programs that we use to help figure out the camshaft.”
To top it off, the Buick big block will get Cometic gaskets and Federal-Mogul, MAHLE or King bearings depending on the application.
Upgrading from an 800hp factory iron block and iron heads, this blue GS Stage 1 will be seeing some faster times on the track with this 530 cid aluminum Buick big block installed.
Engine of the Week is sponsored by Cometic Gasket
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