This is the car we drooled...
This is the car we drooled over: a '70 Javelin owned by Dennis Allen. He pulled the 304 and dropped in a 401 with all of Edelbrock's AMC trinkets. He converted the Borg-Warner to a 727 TorqueFlite automatic and used Matador police-car parts for brakes and a pair of chopped springs to get the ride height down. The differential is the stock Model 20. Dennis's Javelin uses American Racing TTOs, 15x7 front and 15x8.5 rear, and BFG tires on a common bolt pattern.
We wanted a Javelin bad. So we got all squinty and slack-jawed when we found a bunch of other Javelin guys on eBay bidding our Big Bad Blue '69 1/2 Go Pack dream car to death. Losing that auction got us thinking about the "wrong year" Javs and Ramblers we could buy cheap and plumb with beefed AMC running gear. Since our requisite engine for any AMC street machine is the 401, we went looking for alternative body styles that weren't coveted or even marginally collectible so we wouldn't feel guilty about yanking the stock engine for a big-cube swap-o. We didn't rule out the larger but still kick-butt Ambassador series or the Rebel, the big 'ol Marlin, or even the gas-crunch stuff from the '70s. We looked at models built after 1965, because stuff before that was just weird, and before 1977 when the Concord hustled in the age of the luxury compact that led to the ultimate demise of the auto division. Ugh.
So here's the deal: We dug up some archive photos of the cool musclecar-era body styles and listed some of the parts, tips, and tricks we found in our AMC fervor. There is way more information available than we can put in this story. So consider this a primer on what is possible. We're still trying to decide which one is coolest, so if we score a roller, we'll unite it with a screamin' mill and let you know.
The alternative is this '74...
The alternative is this '74 Javelin owned by 19-year-old Brian Layden. It uses a 0.030-over 401 with 12.5:1 compression and Indy cylinder heads to run 13 flat at 109 mph on street tires. Somehow the Javelins avoided the '74 ugly bumper syndrome and got away with rubber guards instead.
Body Styles
Like we said, the dream was buying a '68-'69 Javelin SST or AMX with a four-speed and either the 343ci or 390ci engine. Great cars, but we couldn't even find a rusty one that would make a good base for a street machine. Everything we found was either restored and expensive or returning to ore. During our search, we did find some Rambler Americans that came equipped with the small V-8s from the 290-360 family. Since the external engine dimensions are the same as the 401, a swap would be easy and their light weight would make them fly. We also found several of the less-coveted '71-'74 Javelins at reasonable prices and a Rambler Rebel SST convertible. Many of these cars were for sale for less than $4,000. Check out the cool bodies and consider the options.
Engines
All 290-401 AMC V-8s after 1966 are in the same family. But just because the 390-401s have the same dimensions as the smaller 290-360 engines doesn't mean you can bore and stroke your way to any cubic-inch displacement with any block. There are differences internally. The most notable is the switch from 7/16-inch head bolts to 1/2-inch head bolts and the deck height increase from 9.175 to 9.208 inches in 1970. This is actually OK because most of the aftermarket parts we've found are designed for post-'70 401s found in fullsize AMC passenger cars until 1974 and in fullsize Jeeps through 1978, making them more plentiful than the early engines.
The Rambler American got a...
The Rambler American got a redesign in 1965 and eventually morphed into the SC/Rambler 390 in 1969. This base model 220 would make a killer sleeper with running gear from a mid-'70s Jeep Cherokee or Wagoneer.
Rearends
Most of the AMC V-8 cars were saddled with the ill-reputed 8 7/8 Model 20 rearend. The problem has always been that the axle is a separate component from the hub. To make matters worse, the axle uses a Woodruff key instead of splines, creating a potential to spin the axles in the hub and snap the key. Short of changing rearends, the fix we've seen used universally is a Detroit Soft Locker, Auburn differential, or similar design with a Moser one-piece 29-spline axle to put up with the abuse. If you're going racing with 500 hp or more and launching hard on slicks, there are Dana 60 and Ford 9-inch bolt-in housings available. Otherwise, upgrade the 20 and leave it alone.
Transmissions
Early AMCs came equipped with the Borg-Warner Shift Command automatic or the T10 four-speed on the performance models. The T10 has always been a decent piece, but the Shift Command automatic shifts poorly and has little or no aftermarket support for performance use. The reason is that after 1972 you could get the TorqueFlite 727 Chrysler transmission with an AMC bolt pattern from a fullsize Jeep or AMC passenger car. With the door open to all the mainstream Chrysler speed goodies like converters, shift kits, and shifters, it's no wonder the early automatic is more for pleasant street cruising while the 727 is used for Friday night drag racing.
 AMC thought of building a...  AMC thought of building a sleeper out of a Rambler American in 1966. The company packed in a 290ci V-8 and a four-speed and called it the Rogue. They're rare because only one Rogue was built for each dealer in the country. This would be the car we'd want to duplicate using an American 220 or 440 body. Neat. |  We can't forget the Rebel....  We can't forget the Rebel. This '67 Rambler Rebel SST was available with a few different V-8 engines and was built to compete in the big-car market. We've seen V-8 convertibles sell for around $2,500. Eventually, AMC created the Rebel Machine in 1970 with a 390 mill and red, white, and blue paint that we would likely skip if we built a replica. |  The 401 cranks and rods are...  The 401 cranks and rods are forged and tough enough for a performance rebuild. Look for the 5.858-inch rods and the forging mark (left) on the crank. Builders have also been turning down the rod journals and using new 2.100 Chevy rods for performance 401s. |