Project Payback 1968 Pontiac GTO Build Updates

Street Muscle dives head-first into the Pro Touring scene with Project Payback, a 1968 Pontiac GTO built for autocross competition time trials. We’ve partnered with Schwartz Performance and Chevrolet Performance to give the classic muscle car modern performance.

Project Articles

June 23, 2021 – Now We Are Getting Somewhere Again

The latest story on Project Payback covers the extensive cooling system upgrades that C&R spec’d for the GTO. Running open track days in SoCal means track temps that exceed 110-degrees, as we found out filming Season 1 of Pony Wars. Having firsthand experience of what can happen trying to race a boosted vehicle for extended periods in the heat, C&R worked with me to design a system that keep the LT4 cool in the most demanding conditions. We discussed airflow and the impacts of running an A/C condenser and heat exchanger in front of the radiator. Ultimately we felt this was the best option, but mounting the oil cooler remotely and possibly adding its own fan. A set of SPAL dual fans were key to the design as well to pull air through the radiator and heat exchanger.

Meanwhile, things are moving along at Best of Show where the ABC wheeltubs are fully installed, sealed, and painted. They even repaired some rusted out areas of the floor, trunk, and rocker panels. It’s a good thing because we will be starting the seats next and we’ll need some solid metal to bolt them to!

June 8, 2021 – Let’s Catch Up

I know it has been a while, but it’s a good time to catch up. How have you been? How’s your family? That’s great. Let me tell you what we’ve been up to…not much. With all of that fresh stimulus money flowing, many shops are flooded with work. And we had come to a stopping point in this build where I (and the PAM shop) need some outside help to install new wheel tubs from ABC Performance. I mentioned these mini-tubs a while back and until we install them, we can’t order new wheels. We also have some much needed rust repair going on before we weld in our S&W roll bar and front seat brackets. If you have been missing content on Project Payback, you are not the only one (*sniffle). That said, here is some proof of life.

Of course, if you are on the ‘gram and need your fix of this project, feel free to check out some additional updates like the sweet C&R radiator and heat exchanger with the matching SPAL fans I just picked up for the project. Occasionally I post some other related Pro Touring content. If you have a Pro Touring project, especially a fellow Pontiac, I’d love to hear from you.

February 27, 2021 – Driving On

Well, I am happy to say that I finally finished up the Holley LT4 wet-sump accessory drive system, aside from the wiring and plumbing, which will come later. Shortly after, we started to get caught up on the chassis and brakes stories. On the latter, we take a close look at why we went with the Baer 6S 14-inch brake package and full floating rearend. Schwartz Performance highly recommended this setup, and with more than one experience with pad knock-back and unresponsive brakes it was a must-have for me. The chassis story takes a close look at why I chose the Schwartz chassis, including the price – believe it or not. Fab work isn’t cheap!

If you are wondering what is next for Project Payback, the GTO is getting the wheel tubs replaced to run some wider rear tires. Once Best of Show does its magic, we should be able to fit up to 345mm of rubber in the quarter panels. Hubbahubba! The wider wheel tubs will allow us to get a solid measurement for a set of custom wheels. In case you are wondering, the 17-inch Billet Specialties wheels are loaners from Project Max Street (currently disassembled) and just barely clear the brakes with the wheel weights knocked off. There is a reason Baer recommends 18-inch wheels at a minimum with these brakes, but they’ll do just for rolling around. We’ll have more stories on Project Payback, including the powertrain installation, in the coming months.

January 3, 2021 – Project Car Two-Step

Man, time flies. I wish I could say that I was slowly chipping away at this project one day at a time, always making forward progress. But I reached the point in the project where you take two steps backward for every one step forward. Holley was thankfully quick to remedy the missing air/oil separator, however, there was no resolution to the unfortunate reality that the A/C compressor would not clear the upper shock mount. This was a mistake on my part when measuring (using Holley’s diagram). I had thought the compressor would sit farther forward and have plenty of room. It did not. This leaves me with just a few options in order to keep cool in the 100+ degree summers of SoCal.

In the midst of the accessory drive installation, Scott and Noah from our shop came over to install the new Holley oil pan. This turned out to be a bit of an ordeal as well, first because the GM engineers made our lives quite a bit more challenging by going back to RTV to seal the oil pan. In addition, the oil pan bolts to the bellhousing and there is also a mid-plate. The tight firewall (we will need some additional clearance for serviceability as it turns out) and welded cross-bar in the front of the chassis essentially made it impossible to swap the oil pan without unbolting and dropping the trans while lifting the engine.

Onward and upward as they say. After cleaning out the office a bit, I started taking a good look at the new dash and gauges that arrived from Classic Dash and Classic Instruments. While I await some help with the remaining metal work–namely the firewall clearance, wheel tubs, rust repair, and roll bar–I am going to start mocking up the gauges and designing the electrical system.

September 11, 2020 – Steering in the Right Direction

In July, I was able to take a small step forward while our shop is tied up by installing a Flaming River steering shaft. We went with a stainless steel DD-style shaft, connecting with U-joints on both ends. It will provide a solid connection to the rack and pinion that came on the Schwartz chassis, as well as the factory steering column (for now). It was a tidy install, and only required a saw and grinder (which I didn’t have) besides your basic hand tools that most DIY’ers with a better equipped garage can handle. I (thankfully) was able to have our shop cut the shaft for me.

Last month I started on a Holley accessory drive install. Things were going pretty smoothly until I first realized that I did not order the optional air/oil separator that sits on the back of the water pump. The factory one can not be reused with the Holley pump, and I definitely did not want to go without it – knowing how hard I’d be pushing this engine. Once that was rectified, it was smooth sailing…almost… When I went to install the A/C compressor, it was apparent that my measurements prior to ordering the kit were not sufficient. The upper shock mount tube prevents installing the compressor. However, that is when the engine is installed as tightly to the firewall as possible. The next step is going to be sliding the engine forward on the adjustable mounts. It looks like 2 inches will do it. Since we need to swap the oil pan for a Holley one anyways, we should be able to kill two birds. Hopefully we’ll have this install wrapped up soon.

April 19, 2020 – Enter the Vlog

While things are slowing down on the build front, due to our shop–and most of California–being closed, it was a good time to get caught up on content producing. Behold we have the first vlog on Project Payback, which covers the Schwartz G-Machine chassis that will serve as the foundation of this Pro Touring build. I plan to make this a regular thing, so you can follow the build in a variety of forms. If you like low production quality and hearing me ramble in my garage for 22 minutes, then you are in for a treat. But seriously, please be kind – I have feelings, too, you know.

A little over a week ago I did a chassis primer, before we delve into the installation portion. The chassis story goes in-depth on the design of the chassis from the ground up, which is applicable to any 1968-1972 GM A-body. Slightly out of order, we also did a story on the gorgeous Ultimate Headers we are using for the LT4 swap, which are specially designed for the Schwartz chassis. On deck, we will have a video with Street Muscle Editor Vinny Costa (and me again, sorry), which gives an overview on the project and helps you get to know it just a little bit better. Thankfully, this was done by our talented production team and will be featured on the PAM YouTube channel.

January 13, 2020 – Off-Season Musings

Santa was very kind to Project Payback, as he dropped off some goodies from Holley. When installing the LT4 on our Schwartz chassis, it became quickly apparent that the factory wet sump oil pan would not clear the frame. Since I thought I ordered a dry sump LT4 from Chevrolet Performance, I was not aware we’d run into this issue. Thankfully a quick call to Dale Schwartz confirmed we’d need Holley’s LT Retrofit oil pan (PN 302-20). And given our intentions to road race the GTO, we also had Holley send the oil pan baffle kit (PN 302-30) to effectively keep the oil pump pickup submerged. This is a trick little piece that helps bridge the gap between a wet and dry sump during those high-g corners.

But wait, there’s more! One of the challenges of the Gen V engines is that they do not come with power steering pumps (factory applications all have electric power steering), and the A/C compressor does not fit many restomod engine compartments. With its sights on being the leader in LS and LT swaps, Holley was quick to market with a wet sump LT4 accessory drive kit (PN 20-220) to complement the LT1 kit already in production. Recently Holley even released a dry sump LT4 and LT5 kit. The kits are all inclusive, meaning not only do they have all the brackets and tensioners but even the A/C compressor, power steering pump, and alternator. It’s completely plug and play.

On its next trip into the shop, we’ll be installing all of these pieces along with a radiator, heat exchanger, and external oil cooler. This will require some metal work along with larger wheel wells for the rear tires, so that we can measure for and order the wheels. Oh and by the way, I finally found a new home for the chassis – which will be going under a 1946 Ford 2-door coupe.

While this stuff is all crucial to the build, sometimes the details can really make a build stand out. For example, one idea I had was to paint the LT4 supercharger lid “Pontiac Metallic Blue” engine enamel as an homage to the factory 400. Is this poking the bear or a trick detail? Sound off in the comments below.

October 30, 2019 – Things Are Getting Serious

Between the $10K Drag Shootout and the Junkyard Challenge it was hard to get some shop time. Especially with the amount of work that was needed to get this project going. But finally things are starting to get fun again. My long-time friend Greg Lovell of AntiVenom agreed to fly in and bail us out of our backlog by tackling the GTO and a few other projects, while the rest of the crew worked on the race car. Greg made quick work of the GTO: bolting up the Lingenfelter-tuned LT4 and Chevrolet Performance clutch, bellhousing, and T-56 Magnum combo – then lowering it onto the frame. The Schwartz Performance chassis came with Gen V-specific adjustable motor mounts (yes, they are different than LS engines), which are pretty trick because they help set the engine back pretty far up against the firewall. The big-block was much more centered, but also not as far behind the axle centerline. This means our weight distribution will be much better. We’ll be going with an aftermarket A/C system, so there was no need to clear the large evaporator box along the firewall.

For the transmission, Silver Sport sent us everything we needed for pedals, hydraulics, and wiring. It is crucial that you use proper pedals as I found out on my G-body project, simply retrofitting a pedal that was designed for a mechanical clutch linkage is not typically a good option. Greg had to cut the floor for additional tunnel clearance. Silver Sport provided a template, but our aftermarket chassis appeared incompatible. He bent some sheet-metal and away he went – it came out great! The tunnel was capped off by a piece of tin from Silver Sport with the shifter cutout to place it within a factory center console. Having been in T-56 equipped A-bodies before, I really liked this option. The last thing you want is uncomfortable shifter location. Silver Sport has a few options on their kits, and this is one of them.

For the next phase, we are measuring for the radiator and heat exchanger as well as the wheels and tires. Stay tuned for more updates as we get closer. In the mean time, I have to figure out what to do with this stock frame…

August 12, 2019 – If I Said You Had a Beautiful Body…

When I think of a “muscle car” I think of an A-body. The lines are what drew me to purchase the GTO and start this project, and so it was very important that they be preserved and perfected. Thankfully I had a fantastic body shop at my disposal, Best of Show Coachworks, that was able to mate the National Parts Depot quarter panel skins to the existing body. The area that mates to the deck lid on the rear-facing portion of the quarter panel had to be made by hand. We also found that fitting the aftermarket Endura bumper was incredibly tricky. There isn’t any give to the material to shape it, so the best you can do is make adjustments. Check out the full story for more info.

March 16, 2019 – Saying Goodbye to Old Ways

The ’70s Pontiac 400 and Turbo 400 that came in the GTO found a new home. I was very happy that within just a few days its new owner had it up and running in his ’68 Firebird. As much as some may question the use of a “Chevy” engine in the Pontiac, in doing so I have helped give life to someone else’s project. So that was nice to see.

March 15, 2019 – The Chassis Hath Arrived

As they say, perfection takes time… But at long last, our beautiful new chassis has arrived from Schwartz Performance. Rolling off the enclosed transport, behind a flawless Thunderbird and a Nova I would have happily tucked away in my garage, the Schwartz chassis gleamed in the SoCal sunlight. Complete with wooden wheels, I sat on it and made engine noises until it was time to roll it into the shop.

The Schwartz G-Machine chassis is not just beautifully formed, welded and powder coated, it has many subtle features that we will attempt to touch on here. For starters, it comes completely assembled. Yes, completely. Second, all of the brake lines are run through the frame like a high end motorcycle or bicycle. It has a modern rack and pinion, so it steers like a brand-new car; Ridetech coilovers, which are manufactured by Fox Racing; and splined sway bars. Overall it is a healthy mix of “street” and “race,” which is just the way any Pro Touring vehicle should be. Best of all, it still relies on a parallel four-link. This suits my driving style, comfort level, taste, and (frankly) budget nicely – much better than a 3-link or torque arm suspension.

Another awesome feature of the Schwartz chassis is that it allows for a variety of transmission and engine combinations. Ours came with the billet aluminum engine mounts for a Gen V small-block, but if we later decided to go back to a Pontiac engine we could. And there is even some adjustability in the engine position, should you want to push the firewall back for better weight distribution. Honestly, that is tempting and something we may consider down the road. At the very least it takes into account any OEM variances between the various A-bodies as well as what 50 years of heat cycling and, well, life can do.

For an in-depth look at the chassis you’ll need to stay tuned for a full story on Street Muscle. In the meantime, we’ll keep updating you as we prepare to put the ‘68 GTO under the knife.

January 12, 2019 – New Year, New Project for Street Muscle: Pro Touring 1968 Pontiac GTO

In August we introduced Project Payback, our 1968 Pontiac GTO – a Pro Touring machine with a downright nasty attitude. If you like A-bodies, Pro Touring and watching tires being spun in anger, this is the project to follow. There is no shortage of autocross events specifically for muscle cars in Southern California, not to mention three excellent road courses within 3.5 hours drive. Ultimately we’d like to see what Project Payback can do on a larger stager at Ultimate Street Car events and the Holley LS Fest.

But, first things first, let’s get to the building. We spent the second of last year planning for the first stage of the build while the initial body work was being completed. We were extremely fortunate that National Parts Depot had everything that we needed to repair the sheet-metal on the quarter panel and fender that had been poorly slathered in body filler prior to purchase. NPD and Best of Show Coachworks have been great partners thus far in the build, and we should be publishing that body work story here soon.

On the mechanical side, we have taken delivery of the entire powertrain. I know there will be purists that say Poncho power is all you need, but we decided to go a different direction on this build. It is true that a stroker kit, valvetrain upgrades, aluminum heads and intake with a quality carb or EFI setup will be make over 700 horsepower naturally aspirated using the factory 400 block. However, our intentions on this build were not to be quite so faithful for nostalgia’s sake. Instead, our goal is to win. We need the sort of reliability that will allow the car to run well on track with minimal changes despite dramatic elevation and atmospheric changes, to drive cross country if needed, and to withstand sustained as well as oscillating lateral g-Forces. For that reason we chose a dry sump Chevrolet Performance LT4 crate engine. And to back it up, we have a Chevrolet Performance T-56 Magnum 6-speed manual transmission and Silver Sport A-body conversion kit.

Not to take anything away from the 650 horsepower powerplant, but the key factor in making the larger A-body hang with some smaller and lighter setups on the autocross course is the chassis and suspension. I put a great deal of research into figuring out what was going to make this car the most competitive, and ultimately it was clear that we needed a whole chassis rather than some bolt-on suspension upgrades. This car had a rough life, so the stock chassis may not be in the best condition (though its measurements did checkout OK). Thankfully Schwartz Performance had us covered. I have been watching their Tempest run for years, so turning to some fellow Pontiac lovers seemed like a natural choice for the GTO. Since second-gen A-bodies come with a 4-ink and coil springs in the rear, the biggest benefits by going with an aftermarket chassis are rigidity and modern steering. Schwartz says its frame is torsionally 200% stiffer and weighs 125 pounds less than the stock chassis. Of course, we will have many other killer parts built into the Schwartz package including massive Baer brakes, Ridetech coilovers, and a Moser full-floating 9-inch. Oh, yes, we’ve come to play.

As I type this, Schwartz is finishing up the chassis to get it assembled and shipped off to PAM’s HQ where we’ll be doing most of the mechanical work on the GTO. Stay tuned for another update when the chassis arrives.


About the author

Scott Parker

Scott dreamed of being in the automotive media in high school, growing up around car shows and just down the street from Atco Raceway. The technology, performance capability, and craftsmanship that goes into builds fuels his passion.
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