While looking at intake manifolds on the net, I came across the designation "High Deck".
What is it, and does anyone have any pros and cons?
Longer stroke?
More torque?
What's the application?

 

A: dimension from centerline of crankshaft to cylinder deck (surface that heads bolt onto).

factory units found in trucks. aftermarket units made mostly for larger displacements. they require extra work to fit into most vettes.

try some forum searches

 

I believe these were used in trucks. GM raised the deck height, maybe for longer stroke for more torque.


BILL SR

 

They raised the deck to allow the use of 4 ring pistons. I believe the only GM tall deck truck motors were 427 cid's, but I may be wrong.

 

So, the higher deck would set the intake and carb higher, right?
Thus causing a hood clearance prob?
I can see a possible header clearance prob too?

 

366's also, same dimensions though

 

Yes, the intake/carb will physically sit higher, and the cylinder heads will be further apart as-well, making header-fitment a problem with off-the-shelf pipes:
because the heads are further-apart, a wider intake is needed.

 

I was told by a long term vette shop owner, that in all his years of messing with vettes, trucks, cars etc....that he has seen maybe two tall deck blocks, apparently very rare......and out of all the BB heads, he has run across maybe 1/2 dozen of the more rare versions.....I forget if it's square or round ports.....I have never owned a BBC, so I lack personal knowledge of same....just reporting what I thought to be interesting comments....

 

Most of the tall decks you are going to see are aftermarket. Unless you're trying to build a 1,000hp pump gas monster I'd stay away from a tall deck block. It really complicates EVERYTHING. It can, and has, been done in a C3 but it's not for the faint of heart.

 

A tall deck block is basically there to suit a larger crank stroke combined with a normal size rod that will still fit a std type piston. This makes for a stronger and more reliable piston and ring land and less rod angularity with longer strokes.
I have no experience with them, but seen our cramped engine bay's i think it would be a PITA to get them in.

 

I put a 9.325" deck block in an 82 a few years ago, it will fit. As mentioned, you'll need the appropriate intake manifold for it, or you can add spacers between the intake and the cylinder heads. The headers/exhaust manifolds will need to be changed as well since they will also be wider and higher compared to the stock location with a standard 9.025" deck. You'll also need longer pushrods and longer connecting rods depending on your stroke and piston compression height.

A short deck block, would require a narrower intake and position the exhaust closer and lower than stock.

 

The raised cam, tall deck small blocks is the Best way to build higher powered small blocks.

Because the motor is a V-8, you are not going up the deck height difference. 3/10 of an inch deck is really nothing towards fitting under the hood. My Dart heads have .600 raised exhaust ports. Not a big deal. Because it is not much higher or outboard enough to hardly notice.

If you are referring to big blocks. A typical BBC is limited to about 509 ci. The after market tall deck BBC's have a practical limit of about 632 ci.

 

Not sure if this has been mentioned yet, standard deck height is 9.8" and tall deck is 10.2". I have a tall deck block ready to go if anybody is interested.

 

The distance between where the distributor sits and the gear is different too.

I just bought the way cool MSD tool that measures exactly where your dizzy should sit. I admit it - I'm a tool junkie...

http://store.summitracing.com/partde...0&autoview=sku

 

The 366 (smaller bore ) and 427 truck blocks were mostly put in
2 and 3 axle dump trucks which means they had a hard life and is
the reason you rarely see one around they were well used up,
they were not put in pickups or cars.

 

They are great for a good sized stroker crank. Free cubic inches. They have spacers for stock intakes and intakes that actually fit these things.

 

What he said times 10!!!
-P

 

Yeah, I have one, too. Building it now. As I just wrote on the thread discussing static vs. dynamic compression ratios,


Combination is as follows:
427 tall-deck BBC, bored .060"
4.5" stroke, 6.7" rods, forged pistons, ARP studs and H-beam rods, internally balanced.
My calculations indicate the TDC will be .020" below the deck height, -3cc valve relief.
I just scored a set of 290 large-oval heads, 2.19/1.88 valves, ported and blended bowls (for $350), ready to run. 106 cc chambers (polished).
With a .039" compressed-thickness head-gasket, I come up with (IIRC) a static compression ratio of 9.8:1.

The intake will be the Dart tall-deck oval-port version. It might kill a little torque, but not in numbers that'll matter for the average rodder...

I am not sure which cam it'll be, but I know that the red-line of the engine will be 5500 RPM, limited both by critical piston speed AND piston-ring acceleration limitations. Also, I'll install a hydraulic flat-tappet cam, avoiding the unnecessary costs of the "sexy" parts, and the decreased reliability which may occur due to the roller-lifter needle-bearings failing.

So I'm probably going to make this an idle-5000 torque GUERRILLA, that'll idle on pump-gas. My estimate is 475HP @5000, and ~600lbs-ft of torque at 3000, with torque exceeding 500 lbs-ft from 2000 to 4500. (Going off memory, here.)

The irony is, I'm using good-quality parts, but not using a water-cooled checkbook to build a monster, which should idle like ANY stock big-block... But pin your eyeballs to the back of your head any time you step on the go-pedal...

As the parts arrive, I'll post pics, on this. A coworker was considering using this exact engine in his '72 roadster. I realized that this would require (probably) solid motor-mounts, block-hugger headers, and a smaller-diameter power-brake booster... But he's since backed out, since his two daughters in college take the lions-share of his $$$...

 

Y'all are commin' up with some great info, THANKS!

Hey breathial,
I can't wait for the pics and more info as it all comes together.

 

[QUOTE=breathial;1562947762]


Combination is as follows:
427 tall-deck BBC, bored .060"
4.5" stroke, 6.7" rods, forged pistons, ARP studs and H-beam rods, internally balanced.


I used the more common 4.25 stroker in my 509 ci BBC. I was just wondering how much grinding that it took to clear the 4.5 inch stroke? What kind of ci do you end up with?