Description:
Our 427ci mechanical-roller LS iron long blocks come in two primary flavors: conventional and copper head gaskets. The Cometic MLX gaskets we use have a max boost rating of 35 psi. This long block has copper head gaskets with fuel hoops which can hold more boost and generate more horsepower. This iron LS long block also has numerous parts upgrades relative to its sister with conventional head gaskets. These include:
- Upgrade from Callies Apex to Callies Magnum crank
- Switch from Callies Ultra Enforcer connecting rods to custom aluminum rods
- Custom Diamond pistons with full round skirts and H-19 tool steel, 0.927" pins
- Upgrade bronze-bushings lifters to DLC (diamond-like coating)
- Upgrade from Jesel aluminum to Jesel steel shaft rockers
This is a custom build so you are not locked into this exact recipe. Want steel rods? Do you think the aluminum shaft rockers will be adequate? No problem. Most of our copper head gasket builds are mix and match.
These long blocks are intended for Drag & Drive running gasoline on the street and alcohol on the track. The emphasis here however is track. The mechanical cam enables higher rpms and higher valve lift for more air flow. That means more horsepower. The mechanical roller lifters are less prone to failure than their hydraulic roller counterparts. One trade-off is that valve lash needs to be checked regularly. The DLC type lifters in this long block experience negligible wear so actual valve lash adjustments are infrequent.
We use Dart SHP blocks and incorporate three major upgrades as part of our precision CNC block machining process. The first is going from 7/16 to 1/2 inch head studs. This greatly increases clamping force on the heads. Second is replacing the main bolts with main studs. The third is machining the lifter bores to 0.904" from the stock dimension of 0.842". The larger lifters are far more reliable at higher horsepower levels.
The rotating assembly starts with a 4.000" stroke, Callies Magnum center counterweighted crankshaft. Riding on the rods are 4.125" diameter, custom Diamond pistons. Their full round design provides more support and greater stability. The upgraded wrist pins add strength. This combination yields a 427 cubic inch displacement.
Aluminum rods are used in place of steel rods for the following reasons:
- Aluminum rods act as shock absorbers thereby adding longevity
- Their lightweight allows us to add weight to the piston
- An aluminum rod failure is far less catastrophic than a steel rod failure
A downside of aluminum rods is their fatigue behavior which requires them to be periodically replaced during refreshes.
On top are our BRE-machined All Pro cylinder heads filled with the parts you need to push this engine to the limit. We start with raw castings so the ports, runners and combustion chamber are all custom. While we prefer LS7 ports, we can machine LS3 ports into the heads if that's what you need for your existing intake manifold. The port work does not change the valve angle which will remain at 12 degrees on the LS3 variant. The All Pro's are assembled with Inconel exhaust valves and Severe Duty Manley intake valves. The Manley NexTex spring kit has a coil bind rating of 0.960" allowing high valve lift. Titanium valves are a great upgrade. The Jesel 1.7:1 steel shaft rockers stabilize the valve train at high rpms and allow easy valve lash adjustments.
Some of the other key features of this long block are:
- Callico coated Clevite bearings
- Billet double chain timing set
- ATI Super Damper
- Manton pushrods with upgraded tips
We strive to keep key components such as block, crank and heads in stock The parts which we may need to order are not exotic and should be availble within reasonable time frames.
A variant of this long block powered Nick Cryer and his 1933 Ford Coupe to a win at Sick Smokies 2025. He was running on gasoline at the time. His engine has copper head gaskets, steel rods and aluminum Jesel rockers. He switched to methanol for 2026 and placed 2nd in Sick Week's Unlimited Class where he hit new PB's there of 7.007 seconds and 198.52 mph. As he says in the video below, he plans to keep slowly chipping away toward his goal of 6's and 200 mph.
If you're thinking you want even more power, billet aluminum blocks are the top of our LS horsepower ladder. These are available with and without water jackets.
Please give us a call to ask questions, price some custom options or get one started. 815-725-2727.
Notes:
- These long blocks are not polluton controlled and may not be legal for transportation in your vehicle.
- Photoset includes pictures of completed engines for illustrative purposes only. The addititional parts are not included.
- Nick's long block used an SHP Pro block. These are no longer available. A key difference between Dart's SHP and SHP Pro blocks was main fasteners. We replace the main bolts with main studs which had been standard on the SHP Pro.
Accepted methods of payment: Cash, money order, wire transfer, ACH
The additional videos below will give you additional information about our machining capabilities and the key parts (All Pro heads, Callies 8-cwt Magnum crank, Dart block and Manton pushrods). We think you'll be as convinced as we are that this long block is best in class for this power range.
The grooves for the hoops are machined into both the block and heads. This requires the high level of precision characteristic of our CNCs as can be seen in the video below:
