Steve Petro, owner of the subject engine, wanted to build a fun ’77 Trans Am SE that would be the calling card for his specialty auto sales business, Rev Up Motors.
Steve Petro’s 436-inch “400” produced more than double the horsepower and torque on the Pierce Race Engine’s DTS Dyno than it originally did when Pontiac screwed it together in ’77 for Steve’s Trans Am.
CLICK THE BELOW IMAGES TO SEE A LARGER VERSION OF THE PICTURES.
1 The original 400 had served Steve well and was in good shape internally when torn-down, but he wanted to boost power while freshening it up, to make the car a bit more enjoyable to drive. His goal was simple: double the engine’s 185 horsepower rating from the factory on pump gas.
2 Here’s the block after cleaning and standard prep work, all handled by Pierce Race Engines. Note the two-bolt mains. The block was deburred, the cylinders were opened up to 4.165-inch, the mains were align-honed, the decks were milled to true them up, and new cam bearings were installed along with fresh core plugs.
3 The four-inch stroke cast steel crank came from Butler Performance and was responsible for a good part of the engine’s displacement bump and monster torque.
4 The #2 & #4 main caps were drilled and tapped to secure a factory-style windage tray, then the caps were secured to the block with ARP main studs.
5 While a forged crank and four-bolt caps would have added some upper rpm durability, Steve didn’t plan to run the engine at sustained high rpm, so the cast crank and two bolt caps were deemed more than sufficient.
6 Custom .045-inch over Diamond forged pistons with 8.34cc domes would yield about 9.5:1 compression with the 4-inch crank and 6.8-inch H-beam rods from Eagle. The ring gaps were checked and filed to fit, as needed, then their gaps were indexed to minimize blow-by.
7 The new piston and rod assemblies filled up the block quickly and would bump compression to about 9.5:1 with the 6x heads’ 102.7cc chambers.
8 You can’t tell true compression without cc’ing the cylinder volume with the piston at TDC, and that’s what’s going on here.
9 Here, you can see the Comp Cams hydraulic roller cam inside the deburred block. A hydraulic roller was chosen to minimize lobe wear. A double-row timing chain and gears linked the cam to the crank.
10 Here, the cam is being degreed to ensure it was ground as indicated on the cam card.
11 Piston-to-valve clearance was checked with lightweight valvesprings. Note the Harland Sharp full-roller aluminum rockers.
12 Oiling system mods were few: a new Melling high-volume pump was equipped with a Nitemare Performance pump cover plate to eliminate pressure fluctuations, and a windage tray was installed – also to minimize pressure changes.
13 Here’s a close look at the difference between the stock oil pump cover plate (left) and the extra-thick Nitemare Performance cover plate, installed. The standard cover will literally flex and bend, allowing the gears to move and therefore pressures to change.
14 The engine really started to come together when the rebuilt 6X heads went back on, with new valve springs, retainers, locks and valves. The stock oil pan, timing cover and water pump were used to retain the stock appearance and save a few bucks.
15 Wearing a fresh coat of GM Blue and sporting its full valvetrain, including the Harland Sharp rockers and custom-length pushrods, the engine was just about ready for testing.
16 Fully dressed out with Ram Air Restoration Enterprises tubular exhaust manifolds and other goodies, the engine was ready to go on the test stand for break-in and inspections.
17 With a test carb installed for break-in, the engine was nestled into a break-in stand constructed from a modified F-body (or X-body) subframe. Breaking it in on a test stand allows you to check for any leaks or problems and correct them before spending big bucks on dyno time.
18 Here, Dan Jensen is performing one of the numerous metering rod and hanger changes in the never-ending quest for optimal power on the DTS Dyno at Pierce Race Engines.
19 Yup … that’s Dan again … with another metering rod and hanger change. Dan’s one of the best in the business at tuning Rochester Quadrajets for max power.
20 Dan tweaked timing several times, too, as high as 44 degrees, which proved to be too much. The engine made max power with 41 degrees total.
21 Here, Dan prepped the engine’s original carb to replace the test carb. The original was restored by Jim McGowan at The Quad Shop and jetting was just about perfect – Dan tweaked it with a hanger change.
22 What’s it take to fine-tune a Q-jet on the dyno? For Dan, it comes down to patience, experience and a boat load of hangers, metering rods, jets and miscellaneous “spare” parts.
23 Testing the engine with it’s original carb and an air cleaner base yielded a power leap to our best pull of 446.5 hp with 481.8 lbs-ft of torque. BSFCs had actually dropped a little, so changing that hanger again may have yielded better than 450 hp, but our crew was satisfied with the engine’s performance, as it had more than met the goal.
24 Here, Dan Jensen (left) and Steve Petro (right) sport big grins after a hard day’s work in the dyno cell at Pierce Race Engines.
All Revved Up
Growing up in suburban Detroit where almost every dad on the block worked for the “Big Three,” it was not hard to fall in love with cars. It seemed like every garage had a new car in it at the time. My passion with cars grew while playing with my Hot Wheels and grew more and more every day as I got older. I would ride my bike up to the store to see if they had the latest issue of Hot Rod and Car Craft magazines.
On my 12th birthday, my parents took me to see Smokey and the Bandit. When Burt Reynolds drove the Bandit Trans Am out of the back of the semi trailer ... I was hooked for life! It was a life-defining moment for me, even at 12 years old.
I followed my dad’s footsteps and went into the automotive industry. After working 20 years in Engineering and Design for GM, it was time to take my hobby of muscle cars to the next level and start Rev Up Motors.
I have had the privilege of owning some real nice cars along the way. With owning hundreds of Trans Ams, I have noticed a common theme with many of my customers. They loved the second-generation Trans Ams, but one thing was lacking ... POWER! Especially for the later models. After having several real fast cars, I wanted a 1977 Special Edition Trans Am that looked stock to the untrained eye ... but wasn’t.
I located the car I always wanted and started to just do a repaint on it. Then it snowballed into a complete rotisserie nut and bolt restoration. After talking to Dan Jensen, I told him I wanted my car to be scary fast but to appear stock in the engine bay. A few other requirements were to have over double the horsepower of a stock engine and run on pump gas. We could have achieved this goal easier by starting with a 455 engine, but I wanted to start with a 400 block and heads and see if it could be achieved.
The engine build exceeded my expectations in every way. It definitely kills the tires and pulls very hard throughout every gear, without any loss of power. This particular car was delivered to the dealer on my birthday, the day I saw Smokey and the Bandit. Coincidence? Fate? It’s just the right one, the worthy one. — Steve Petro