Mopar Action On-line – Tech Questions
Adam Buff, Panama City, FL, 1968 Dodge Dart 360
First of all let me start by saying that you guys rock! Itrust no one else for Mopar tech. My question is fairly straightforward.
Are there any differences or prefences in choosing a 360 block for a rebuild? Ihave a choice between a 1977 360 with approximately 50,000 miles from adiplomat, or a 1991 360 with 110,000 miles from a 2500 series truck. I planon an over-boar [sic] with Hypereuteutectic zero- deck flat top pistons,topped off with “J” heads with a mild port/ polish, an Edelbrock RPM”Airgap” and a Holley 650 double pumper. I already have TTI headers, and amlooking for somewhere near 350-360 +/- horsepower. I am trying to find ifone has better castings, and rods. I know that the 1991 motor is a factoryroller, and also want to know if there are any performance cams that can beused with the factory valvetrain if I go with the 1991. Thanks in advancefor any and all assistance given.
Sincerely, Adam Buff
Anecdotal evidence (not supported by anything I’ve ever personally seen)suggests that pre-’74 360s used 340 cores, and, therefore, should havethicker cylinder walls. But since both of your choices are newer than that,it’s moot anyway.
Without hesitation, and subject to a physical inspection, I’d go with thelow-mileage passenger car engine. Less thermal cycling, stress, etc. If youtoss my advice over your shoulder, you can use any cam and lifters in the’91 Definitely stay away from the roller setup! The rods are the same deal.Put new bolts in whichever ones you go with, a mag check isn’t a bad idea,either.
Now for my 2 cents worth! First, why use a double pumper and a dual plane?If it’s a high-torque low-RPM buildup you’re after, use a vacuum secondarycarb, or a new AVS. And, if you wanna go fast, lose the dual plane!
Next, you DO know that those ’91 heads – 308 castings – are way better thaneither X or J castings, right? And they have induction hardened valve seatsas a bonus.