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Muscle Car Tech Tips - What's Your Problem?

Big-blocks swapped into Camaros and why to avoid 305 Chevys like the plague.

We're amazed that the second-generation ('70-'81) Camaros/Firebirds continue to occupy a second-class position in the musclecar hierarchy.>

Rat Swap With a Twist
Brian Sefkar, Baraboo, WI: I recently bought a '78 Z28 Camaro with a bone-stock 350 and automatic. I was wondering how much trouble I would have running a 454 big-block Chevy? Can you give me setup tips for the front suspension, shocks, and the like? Will this work or am I looking for trouble? Thanks!

Jeff Smith: The only trouble you're going to have, Brian, is keeping rear tires on your Camaro, because you'll be smokin' those babies with all that Rat power. While the late-'70s Camaros never came with a big-block, it's a relatively easy swap to convert to one since '70-'72 Camaros came from the factory with 402ci big-blocks. The Rat motor will drop right in and will actually bolt up to your stock TH350 transmission, although we're not sure how long that trans will survive unless you treat it to a performance rebuild with good parts. A better choice would be to swap in a TH400 trans along with the Rat motor. If the 454 is going to be relatively mild, then the TH350 will suffice.

At this point we should recognize that there are emissions questions involved with this swap. Late-'70s cars were fitted with a staggering array of EGR valves, air pumps, catalytic converters, hot-air choke systems, and dozens of feet of vacuum hoses and diverter valves. We did some Internet research, and the state of Wisconsin does perform emissions tests every two years on cars like yours. However, we heard a rumor that by January 2008 it will only be inspecting vehicles '96 and newer, so you might be off the hook. But even if the car does not have to be tested by the state, be aware that this car is an emissions-compatible vehicle and subject to federal laws that prohibit removing or tampering with emissions controls on vehicles operated on public highways. This means you should equip the engine with catalytic converters and probably an EGR valve just to get through the inspection process. It might be wise to inquire at a state inspection station as to whether it's even legal in Wisconsin to do this swap. Or, if the inspection is not going to happen on an older vehicle, you might get by. Either way, consider yourself lucky. In California this swap would not be possible without jumping through a maze of bureaucratic flaming hoops filled with death rays and poison punji spikes. This is just a part of the price we pay for living in paradise. Headers will be an integral part of this swap because stock cast-iron manifolds might not fit unless you can find a set of '70-'72 402 big-block iron castings. But manifolds are relatively restrictive, which brings up why you would want to swap in a 454 only to cork it up with a weak exhaust system. Assuming you have to have a catalytic converter in order to pass the state smog test, we'd suggest uncorking the system by using a pair of monolithic converters just after the header collectors. MagnaFlow is owned by a parent company called Car Sound that makes catalytic converters. We found a universal catalytic converter for your application with a 3-inch inlet and an outlet only 4 inches thick that should work, especially with one for each bank. They had an online price of $106.97 (each) on a retail link from Magnaflow's Web site. Magnaflow also offers a universal X-pipe exhaust system with mufflers for the Camaro/Firebird (up through '73, but it would still work since the floorpans are the same, PN 15896, $473.97, Hedman makes a 2-inch primary tube header for these cars (PN 66105, $204.95 from This will probably be the biggest headache in completing the swap.

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