Mopar 360 Small Block

Top Areas to Modify

Build a High Performance Mopar 360

1. Forged Crankshaft: The stock Chrysler 360 crankshaft is cast iron and externally balanced. It's OK for moderate performance or light racing use, but if you're planning on making serious power it's better to go with an aftermarket forged crank. Affordable crankshafts for the Mopar 360 are available from Eagle and Scat (the Scat cranks are a little more expensive but have a better reputation for quality). Besides being stronger than the factory cast crankshaft, the aftermarket cranks are internally balanced so make sure to get the correct torque converter or flywheel and harmonic balancer to go with it.
2. Connecting Rods: While stock connecting rods are adequate for mild street use, there is work that should be done unless you're on a very tight budget: have them magnafluxed and checked for straightness, replace the rod bolts, and have them resized. By the time you add up the parts and labor, it's almost as cheap to go with a set of aftermarket connecting rods. The aftermarket rods are made out of better steel than the stock rods and they're also brand new - you know they haven't been abused (and possibly weakened) by a previous owner. For most applications a set of I-beam rods (about $350) is fine or if you feel the need you can get a set of H-beam for about $500. The I-beam rods are lighter so I'd recommend going with them unless you really need the extra strength of the H-beam rods.
3. Pistons and Rings: The Mopar 360 never came from the factory in a high compression version. Factory pistons were cast and could have as much as -0.100 deck height, making for low compression and crappy efficiency. For a performance build, you should go with after market pistons with close to zero deck height. Use hyperuetetic or forged, depending on intended power level. Using a piston design that uses 1/16" rings instead of the stock 5/64" reduces friction and gives you some free horse power. For pump gas, don't run over 9.5 compression with iron heads or 10.5 with aluminum heads unless you really know what you're doing.
4. Camshaft: There are almost as many opinions on camshaft selection as there are engine builders. When building a small block Mopar, the main thing to keep in mind is that most cam companies' "stocking" cam designs are likely optimized for the small block Chevy, and are unlikely to be the best choice for you Mopar. Make sure to work with an engine builder or cam grinder who is knowledgeable about what works best with the small block Chryslers. No matter what cam you run, you should upgrade to adjustable rocker arms. The stock, stamped rocker arms aren't adjustable and they cost you valve lift because they only have about 1.42 lift ratio instead of 1.5 as advertised. After market adjustable rocker arms have a true 1.5 ratio (they are also available in higher ratios) and offer adjustability. This is important even with a hydraulic can so that you can properly adjust lifter preload.
5. Intake Manifold and Carburetor: Unless you're building an economy engine, Edelbock's Performer RPM manifold is better than the Performer. It's also taller so you should check hood clearance. I like it with a Holley 750 vacuum secondary carburetor (3310 with secondary metering block installed). If your 360 came with a factory 4 barrel manifold, it's actually a very good choice. The only downsides are the heavier weight compared to an aluminum manifold and the fact that parts for the factory Thermoquad carburetor are hard to find since it's been out of production for so long. Of course, the ultimate setup would be a factory Six Pack - they are available brand new as a complete package for around $2000.