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Big-Block Party Part 3: Prepping our ’69 for the Installation of a Modern, EFI Big-Block

By August 18, 2011Uncategorized

In our first installment, we took you through the process of removing our old, tired, and not terribly exciting small-block. We also showed you how we prepped our ‘69s engine bay for the installation of the new Tri-power EFI big-block.

Part 2 was a step-by-step build plan showing how, with the help of a select list of high-performance suppliers, we assembled this 21st century Rat motor.

This month, we’ll install all the new upgrades we’ve chosen, along with the main ingredients of our project – specifically, the engine, a super-duty Gearstar 4L60E transmission, and a maid –to – order, bulletproof rear end fro Precision Corvette Differential.

There’s a learning curve with every “first-ever’ build, and it quickly became apparent that our C3’s stock automatic transmission didn’t have a chance of handling the new big-block’s output. So we switch to a Gearstar Level 4 electronically controlled 4L60E/four-speed automatic. It has an 11-inch, custom-stalled, full-billet, lock-up torque converter, and its build to handle up to 650 hp and 600 lb/ft of torque. Follow along now as we find out what it takes to get a transmission t Level 4 capability.


Gearstar Performance Transmissions says it “custom builds your transmission to order.” Fortunately, that’s a fact and not just a slogan. Much as you would when having a bespoke suit made, you’ll speak directly to the one master tech, who will then build you transmission – based on your specific requirements – from start to finish. The journey to building a Level 4/4L60R starts with qualifying the case, then high-pressure washing and bead basting it. It’s then re-washed, re-inspected, and painted.

The reassembly process begins with a master overhaul kit with Kolene steels and Raybestos racing frictions. Gearstar uses a carbon fiber, super-wide 2-4 band that utilizes 100 % of the available surface area. Two valve body reprogramming kits are used to improve shift quality and durability, and all of the internal electrical parts are replaced with updated conponents. A complete bushing kit; new, heavy-duty Torrington bearings, and new thrust are also installed.

To handle the addition torque, Gearstar uses a high-capcity pump with a hardened rotor and vanes. The input drum is hardenend and reinforce with a billet sleeve to greatly increase strength, and the clutch drum is also modified, allowing it to tolerate higher RPM levels. Additional clutches and steels are added, which boots clutch capacity capacities by 30%. The Level 4L60E also incorporates a fully dollarized planetary gear set that provides enhanced durability and greatly reduces power-robbing drag. The four-pinion OE planetaries are replaced with hardened five-pinion steel planetary gearsets.

This Level 4 4L60E is one of the most flexible fully electronic transmission packages available, allowing us to completely customize shift timing, shift feel and lock-up application. The bottom line is that every part of the transmission is brought up to super-duty specs so it can handle the power and deliver years of trouble-free service. And Gearstar guarantees every transmission it sells. Welcome to Level 4.


In addition to the transmission, we needed to address a number of items that, upon closer inspection, didn’t look up to the talk at hand. The first thing we did was treat ourselves to the beauty and durability of powder-coating. There’s a whole list of powder coating shops in the Atlanta area where we live, but the name that kept coming up was Millers Powder Coating. That’s probably because Bill Miller is a true hot rod and motorcycle enthusiast and has done powder coating work for virtually every car and bike club in the area.

Once we had our upper and lower control arms coated, we were hooked. We ended up powder coating the entire front suspension, the trans cross member, the rear-diff cross member, and a few other odds and ends. Miller’s can even powder coat your entire chassis in virtually any color you’d like.

Now that our chassis was cleaned and painted, and our front suspension powder coated, we were loath to reinstall the stock power-assist slave cylinder. It’s always leaked, and we were told that a new stock-replacement unit would end up in the same condition in just a few months. The best remedy was to upgrade to a new Borgeson kit compete and includes the hoses, lines, and a new rag joint as well. The installation was straightforward and, best of all, uneventful.

It didn’t make sense to reinstall old brake pads or shock absorbers, either. We chose to upgrade both the pads and rotors with new units from EBC Brakes, They’re specifically designed to work with stock Corvette calipers, and their rotors are slotted and partially frilled to avoid cracking. We painted the calipers with caliper paint to complete the look.

For shock absorbers we were back on the phone with Summit Racing, whose techs recommended QA1 adjustable gas units. We also replaced the stock rear multi-spring setup with a single composite spring from Volunteer Vette. It’ll deliver better ride quality and reduce a fair amount of weight as well. (Volunteer provided our front big-blocks springs too.)

One of the biggest and most noticeable upgrades we made was to eliminate all the stock pulleys and belts and install a Vintage Air Front Runner serpentine belt system, which came complete with a new and more efficient A/C compressor, power-steering pump, and 140-amp alternator.

The Front Runner system it truly a sight to behold. Everything is polished or chromed, the mounts are all one-piece 6061-T6 billet aluminum, and the fasteners and bolts are from ARP. It includes a high-volume aluminum water pump, and the installation is painless. Out only mistake was thinking the job was going to be difficult, which led us to read the install instructions. Vintage Air had simplified this procedure to the point that you can save a lot of time but simply following the picture diagrams.

Prior to lowering the engine between the franmeralis, we removed the lower pulley for clearance, installed a set of Prothane urethane motor mounts, and then laid our Hedman ceramic-coated headers in place.

Once our big-block found its new home, it was apparent the lower pulley wasn’t going to cleat the front cross member. We used a cutting wheel and notched a 1×4-inch section. Another necessary modification involved the power steering pump. Since it’s a universal pump we needed to cut off the plastic return fitting. This allowed it to clear the upper control arm cross shaft.

Finally it was time to bolt up the Gearstar 4L60E. But first, we needed to install the Denny’s HD driveshaft into the rear-differential yoke. The front of the driveshaft slips into the back of the trans, and the trans is raised to finish the installation. Our new transmission does have a slightly larger billet servo on the side, which initially made contact with the trans funnel. Using a small Dremel attachment, we cut a 2×4 inch notch in the tunnel to accommodate it. We’ll need to remove the carpet on the passenger side of the tunnel and re-glass this cut at some point, to keep road noise and heat from entering the interior.

With the engine, trans, and rear diff installations finished, we focused on al the little details necessary to make everything look neat, clean, and professional. We mounted the FAST computer on the inner fender wall, and placed the transmission computer in the storage compartment behind the passenger seat. Both are now protected from road damage and rainwater, and still easily accessible if we need to plug in our laptop. The MSD 6 box and coil are mounted on a 1/4” aluminum plate and bolted to the firewall right behind the MSD distributor.

Next, we routed our 1/2” fuel line and 3/8” return line on the outside of the frame rail, behind the rocker cover. Here, they’re protected from undercar heat and road scrapes, and are completely hidden from view.

For a little more “bling” – and way better cooling – we installed a Be Cool all-aluminum radiator with twin electric fans.

Once we had everything mounted in the engine compartment, we covered our wiring harness with new GM harness covers. They perfectly match the covers on the FAST E-Z EFI harness and give it a clean, modern look. Last but not least, we bled the brakes, had a four-wheel alignment done, checked for leaks, and reinstalled the original hood, which now boasts a reproduction 427 emblem from Volunteer Valve.


We quickly forgot about all the parts and the hours of labor that went into this build the second we turned the key and heard the engine start, and it’s fairly uneventful when they do. When a big-block starts, it sounds like a bomb going of. I clearly remember the first time I heard an original 427/435 fire up. It had side pipes, and it scared the life out of me – the kind of scared when you can’t stop smiling.

David Fulcher took the first spin…literally. As he dropped the shift lever into “D” and touched the gas pedal, the car spun the tires right there in the service bay.

Don’t miss the next issue when, along with final photos, we’ll have the complete report form Waldens DYNO, a full road-test review and our driving impressions-including braking, steering response, handling, acceleration, and even a fuel-mileage summary. See you then.

Vintage Air’s "Frontrunner" serpentine belt system includes everything, including a Stewart aluminum water pump. We installed it while our engine was still sitting in the shipping crate.

Our Level 4 Gearstar 4L60E is built to handle 650 hp and 600 lb-ft of torque. Let’s take a look at what goes into this super-duty trans.

The Level 4 4L60E uses Raybestos Stage 1 racing frictions and hardened Kolene steels.

A Gearstar performance builder installs a custom-assembled input drum into the transmission case.

The Level 4 trans uses a reinforced, carbon-fiber 2-4 band that is 20 percent wider than OE styles and utilizes 100 percent of the drum’s available surface area.

This trans package also utilizes a fully rollerized gearset with a hardened-steel, five-pinion planetary system that reduces power-robbing drag.

A heavy-duty, reinforced drive shell with hardened splines is also used, and is seen here on the right. The stamped-steel OE shell is on the left.

The Input drum is assembled with a heavy-duty reinforcing sleeve that’s designed for higher rpm/racing. It also comes with a hardened input-shaft assembly.

Experienced hands, a hydraulic transmission jack, and an air ratchet make short work of the trans installation. With that done, it’s time to move on the underbody.

Big-block front springs from Volunteer Vette are a must, as is a low-arch rear composite monoleaf spring, Sourced from Van Steel, the latter item is specifically designed for big-block, big-power applications.

The beauty and durability of powdercoating can be addictive. Fortunately, Miller’s Powder Coating can feed our obsession.

Energy Suspension’s urethane bushing kit will tighten up the suspension, motor mounts, and the transmission mount, too.

We decided to lose the leaky power steering slave cylinder and move up to Borgeson’s complete kit. A new Delphi quick-ratio box, all the lines and bolts, and a new rag joint are included.

EBC Brakes’ slotted and partially drilled rotors resist cracking and are designed to work with factory Corvette calipers.

We installed a Be Cool aluminum radiator from Summit Racing, which should improve the heat-dissipating capabilities of our cooling system.

New trailing arms are from Lonestar Caliper. They were sourced and completely assembled by Precision Corvette Differential