A '79 CJ That Breaks All The Rules
An off-road Jeep shouldn't look this nice. A well-used engine compartment shouldn't be this shiny. A little AMC engine shouldn't make this much power. A high-compression ratio and huge boost numbers shouldn't live on pump gas. And a hard-working, blue collar guy with a family shouldn't be able to spend a full month in Glamis each year. Good thing nobody told any of that to Robert Byrne.
A masonry contractor from Riverside, California, Robert is way into taking advantage of the finer things Southern California living has to offer. Namely, rust-free Jeeps and huge open areas in which to enjoy them. He bought the little '79 CJ-5 you see here 18 years ago and has been constantly building it ever since.
We had the pleasure of hanging out with Robert both in camp and in the dunes on a recent Glamis trip. The dude is all about having fun and his Jeep is all about, well, having fun. In fact, after being exposed to Robert's brand of fun we found ourselves trying to figure how to fit a turbo to our flattie. Or build a blown big-block sand Jeep. Who says the afflicted can't get infected?
Chassis And Driveline
Okay, let's not dance around the issue. The star of the show is clearly the Paxton blown AMC engine. So what is it? A honkin' 401 stroker? A juiced-up 360? Nope, it's a teeeeny little 304. In fact, it's the original '79 block that the Jeep left the factory with. But that's where factory ends.
For starters, the little AMC 304 was gutted and given a quality rebuild. The refurbished crank is a stock AMC part and the stock rods have been shot peened to relieve stress risers and increase strength. In a fit of glorious defiance, a set of 10:1 forged TRW pistons were fitted to the rods and slung in the block. That's a lot of compression for a normally aspirated engine, let alone a supercharged one! A set of iron AMC heads was ported and polished, fitted with upgraded valves, good springs, and roller rockers to better deal with the high-lift Crane camshaft. The whole shebang was topped with an Edelbrock Torker intake and an MSD Pro-Billet distributor to zap the mixture. Boosted engines need a lot of spark, so the MSD is a worthwhile addition. And so are the Thorley headers that dump into DynoMax Ultra Flow race mufflers.
To fit the blow-through Paxton setup, Robert got super high-tech. After all, there were no off-the-shelf brackets to mate the centrifugal supercharger to the AMC block. But it wasn't a machine shop with a fancy CNC-cutter that built the slick aluminum blower mount. Instead, Robert and a buddy went elbows deep on a 1-inch-thick sheet of aluminum with a jigsaw, drill, and tap. The results are impressive.
With the blower affixed to the block, a triple belt pulley was machined down to fit the AMC harmonic balancer. The resulting 10 psi of boost blowing through the Barry Grant 750-cfm Demon carburetor could result in belt slippage if fewer belts were used. By the way, that much boost puts a tremendous amount of stress on the factory cast crank. We wonder how Robert has gotten so many seasons out of the engine without the crank snout snapping off. And we have no idea how an all-iron engine with 10:1 compression can live with 10 psi of boost while sucking down only crappy 91-octane California pump gas. But it does. Color us amazed.
Behind the estimated 475hp small-block lies another slap to the gods of convention. Instead of a big TF727 tranny there is a little TF904 that's been fitted with a 4,000-rpm torque converter, a shift kit, and all the goodies by Koehl's Transmission in Riverside. A B&M Megashifter toggles the gears and sends the power back to the factory Dana 300 T-case that's still running the stock output shafts and gears.
Underneath, logic is further defied. The factory AMC Model 20 rearend is completely stock down to the two-piece shafts, drum brakes, Trac-Lok limited slip, and 3.54 gears. We know Robert's Jeep sees mostly sand use, but come on! We've broken these things in a grocery store parking lot!