As you may recall from the beginning of this archaeological restoration, the history of this Boss 9 is known and documented from March of 1973 until today. However, not much is knows about the car from its original sale in Dallas to when it appeared at a Fort Worth, TX used car lot for the paltry sum of $1475.

There have been some interesting clues about the car's past. It had been repainted though the body was rust free and near perfect. Exhaust cutouts had been installed in the factory pipes just after the stock manifolds. There were the remains of torched-off traction bars still bolted to the leaf springs, and significant rub marks were found inside both rear wheel wells. Though not completely conclusive, all this suggests that this car was more than just a daily driver. How much more is what the staff at Muscle Car Restorations in Chippewa Falls, WI is hoping to find out as they deconstruct its engine, searching for anything that may reveal more of this Boss' secret past.

There are a few things that MCR does know for certain: this is a numbers matching car with it's original engine, transmission, and rearend is still with it. Aside from the missing air cleaner and smog pump, this 429 appears to be intact. The Holley carb is not the factory version but it is from the the right time period. One hint that this engine may have been out of the car at least once is the incorrectly painted intake manifold.

Clearly, the evidence, even though it's mostly circumstantial at this point, suggests at least some heavy duty street action. That's not hard to imagine as that was why many of these types of cars were purchased in the first place.

What further clues will be revealed as MCR goes layer by layer into the core of this 429? Follow along as the crew from Muscle Car Restorations and Advanced Engine Concepts examine the clues.

See all 23 photos This is how it came out of a North Dakota barn after nearly forty years. The master cylinder had been removed by someone in a futile attempt to get the brakes to work, but other than that, this 429 doesn't appear to have been touched since it was stashed away decades ago.

See all 23 photos Bob Perkins, resident Ford authority at Perkins Restoration, confirmed that this is not the original Holley. A quick Internet search of its part number indicates that this model, 3310, probably a 750 cfm, was used on 1965 - 1970 Chevelles. One could imagine swapping out the manual choke original for this electric choke model, except there is no indication that the electric choke was ever hooked up.

See all 23 photos With the engine and transmission out of the car, MCR and Perkins were able to check all the numbers, codes, and markings and confirm that this is the factory installed engine. With the exception of the odd blue paint on the intake manifold, it looks like an intact survivor.

See all 23 photos Removing the valve covers revealed another clue. It's hard to believe the car could have been sold at the dealer like this, only running on seven cylinders. Was this why it was parked so long ago?

See all 23 photos What's going on here? Was a casting flaw fixed at the factory before the engine was assembled or is this some racing damage that was repaired?

See all 23 photos The correct code for 1969 Boss cylinder heads is C9AEA. The D0AE-A A code indicates that this is 1970 head, so at least this has been replaced. This really wouldn't be expected on a roughly 27,000 mile, normally-driven car. Could it be a factory warranty replacement? Or was it something more drastic?

See all 23 photos This is way you never, ever try to start and engine that has been sitting for this long. Clearly, some water/antifreeze has leaked into this cylinder. What sort of damage could this do if you did get it running?

See all 23 photos At the very least, pull and clean the oil pan. You wouldn't want this goo pumped through any engine let alone something this rare.

See all 23 photos Finally, now we have conclusive evidence that the engine has been rebuilt once before. It's long been standard machining practice to mark crankshafts with the amount they have been ground. In this case, this crank is .010-inch under. There is no way that a 27,000 mile car needs a crank ground under normal service. This thing has seen some hard use.

See all 23 photos Here's further proof of the crank being .010-inch under. It's unteresting that the bearings came from Ford. Check out the numbers on this bearing- do they indicate 1969? You tell us.

See all 23 photos The camshaft turned out to be from Crane, so now there is no doubt that someone attempted to increase the power. What they did with that extra power is still a mystery though.

See all 23 photos After testing, that crank was found to be cracked beyond repair (another indication of extreme use) so another factory Boss crank was located. Advanced Engine Concepts set the trust bearing clearance at 0.006-inch.

See all 23 photos New 0.060-inch over stock-style pistons were installed on the original rods as they were found. No reconditioning was needed. The ring gaps were set at 0.024 and 0.026-inches.

See all 23 photos Boss 9s don't use a conventional head gasket. Rather brass O-rings are carefully tapped into groves cut into the heads around each chamber. Rubber O-rings provide the necessary seal around the water passages. RTV silicone is used on both side of the O-rings and on the head bolt threads and both sides of their washers to prevent leaks. It is essential that the heads are perfectly flat so AEC did a 0.004-inch cleanup cut just to be sure.

See all 23 photos It is also recommended to run a small bead of RTV around the entire perimeter of the head to seal out any contaminates.

See all 23 photos Another oddity about Boss 9 heads is that there is a pair of 0.006-inch brass shims that need to be in place under both bottom corners. If you didn't know these were there, they could easily be lost during disassembly.

See all 23 photos There are a surprising number of stamps and markings on these engines. Perkins was invaluable to MCR in helping get these all back where they belong.

See all 23 photos This snorkel type air cleaner is unique to Boss 429s and are very rare. Fortunately, Perkins was able to locate an exact reproduction.

See all 23 photos The engine is finally back where it belongs and is in factory-fresh condition. Aldridge Motorsports and Engineering provided the correct Holley carburetor, and the number "29" on the top of the firewall was applied by Kar Kraft and indicates that this was the 29th Boss 429 that they assembled.

Sources:

Advanced Engine Concepts; 920/294-0474

Muscle Car Restorations; 715/834-2223; musclecarrestorations.com