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Two To Four Barrel Carb Swap

Posted in How To: Engine on October 1, 2012
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The AMC 360 V-8 in our ’78 Cherokee Chief had good low-end grunt, but ran out of lungs above 3,500 rpm. And although we like the off-road performance of the factory Motorcraft 2150 two-barrel, it was time to uncork our V-8 with some Edelbrock parts made right here in the USA. If we had a more aggressive camshaft, Edelbrock’s Performer RPM Air Gap manifold is the natural choice, but the standard Performer manifold (PN 2131) is the best fit for our dead-stock 360. Those needing to retain the EGR can order manifold PN 3731. We topped the Performer intake with Edelbrock’s Thunder AVS 650 cfm Off-Road carb with electric choke. To save some coin, we ordered a reconditioned model, PN 18269. The brand new carb is PN 1826.

We discovered the Thunder AVS carb bowls quickly ran dry once we cracked open the secondaries, so we swapped fuel pumps and ensured we had a solid 6.5 psi fuel pressure through the rpm range. The problem improved, but didn’t vanish, so we cracked open the carb and raised the floats. Again, the problem improved, but the carb still runs dry if you stay in the secondaries too long. We’ll have to swap in a higher-volume fuel pump to cure the issue. But until the carb drains dry, wow, what a difference. The engine pulls way stronger from the bottom all the way up to about 5,000 rpm where the cam falls on its face. It really is like pulling the cork out of a bottle. Our AMC is finally free to rev.

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Permatex Inc.
Hartford, CT 06106

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