BBC Tall Deck vs. Standard
11-14-2017, 08:32 PM
#1
Le Mans Master
Thread Starter
BBC Tall Deck vs. Standard
I'm sure someone has posted all of this before, but here it is again.
Tall Deck Blocks were used in medium and heavy duty trucks. That production ended around 1990. The deck height, measured from the crank centerline was 10.2 inches. Those trucks used 4 ring pistons, and were intended to be a fairly low RPM engine with a big torque. The Holley carb the factory installed had a governor built into it that worked on manifold vacuum. IIRC, that vacuum was ported thru the distributor.
The block is very easy to identify The upper mounting holes for the water pump are about 1/2 inch below the deck.
The short deck blocks were used in passenger cars and light trucks. Light trucks includes the 3500 series 1 tons. 9.8 inch deck height. That same water pump bolt hole is within 1/4 inch of the deck.
The part you need to remember is that when the deck height goes up, the heads move apart. As tight as the Corvette engine bay is with a BB installed, you'll need to think about custom headers and clearance to the master cylinder and A/C if you have that. The intake is wider, but that's no issue these days. There are spacers for the intake, or the major parts companies have intakes available that bolt right on.
Tall Deck Blocks were used in medium and heavy duty trucks. That production ended around 1990. The deck height, measured from the crank centerline was 10.2 inches. Those trucks used 4 ring pistons, and were intended to be a fairly low RPM engine with a big torque. The Holley carb the factory installed had a governor built into it that worked on manifold vacuum. IIRC, that vacuum was ported thru the distributor.
The block is very easy to identify The upper mounting holes for the water pump are about 1/2 inch below the deck.
The short deck blocks were used in passenger cars and light trucks. Light trucks includes the 3500 series 1 tons. 9.8 inch deck height. That same water pump bolt hole is within 1/4 inch of the deck.
The part you need to remember is that when the deck height goes up, the heads move apart. As tight as the Corvette engine bay is with a BB installed, you'll need to think about custom headers and clearance to the master cylinder and A/C if you have that. The intake is wider, but that's no issue these days. There are spacers for the intake, or the major parts companies have intakes available that bolt right on.
Last edited by TimAT; 11-14-2017 at 08:33 PM.
11-14-2017, 08:40 PM
#2
Race Director
I doubt there is a half inch between the master cyl and valve cover in a standard deck big block. In fact, that distance may have something to do with the engine being offset to the right an inch. So raising the top of the head would make it near impossibility to fit these engine compartmets. As long as the block you are looking at says 7.4, it is a standard deck.
11-14-2017, 08:46 PM
#3
Le Mans Master
Thread Starter
I have shaft rockers under extra tall (stock appearing) rocker covers on my 9.8 deck BB. I can put my hand between the brake booster and the cover. I have more problems getting the left cover away from the alternator than I do around the booster/master cylinder.
And a tall deck will fit- just needs a little fab work. I've seen a few 572's installed in C3's.
And a tall deck will fit- just needs a little fab work. I've seen a few 572's installed in C3's.