I have been so busy at work all summer...finally have the new engine in the car and dialed in.
This big block pulls an Ebody around with no problem. A mild big block with iron exhaust has much stronger torque everywhere than a built 360 with headers. So the extra cubes really help. Moly rings sealed right away…had slight suction on the PCV intake hose by the time the cam/lifters were seated in.
Fuel system from the gas tank has in-line filter, then Mallory electric pump ahead of rear axle, 3/8 fuel line feeding Carter street mechanical pump, then vapor separator and on to carb. With the electric pump ‘off’, the mechanical pump feeds with no issues to 3500 rpm…75 mph hwy cruise. But at the stop light you can only pull thru 1st & 2nd gear before the float bowls empty….need the electric pump for clean pulls. I may switch to a higher volume/pressure mechanical pump but would need a pressure regulator and still feed thru the OEM vapor separator…or give up the mechanical pump all together…I like the extra reliability of two pumps for long distance cruises.
Had 14 inches vacuum at 750 rpm smooth idle, with 267/271 cam, 220/223 duration at .05 lift and 112 LSA for iron manifolds. Even at my altitude 5200 feet could have gone for more cam, but would loose the healthy bottom end torque the engine has now for pulling 3900 lb around. I have a set of 1.7 adjustable rocker arms, probably try them at some point…this will increase .05 duration by about 6 degrees; then see how the engine likes it. Maybe switch to a mechanical cam then.
Some engine tune details:
Fuel line was too close to heater hoses/ engine block. These big blocks have issues with the mechanical fuel pump getting hot. I had a fuel pressure regulator, but it did not remove the hot vapors, so replaced it with a big block OEM style vapor separator. The mechanical fuel pump still heats up. Why doesn’t the aftermarket add a ceramic isolator spacer and lengthen the fuel pump lever…like some other vehicles have from the factory….this would go a long way toward keeping the mechanical pump cool.
Need to add a heat shield along side the vapor separator to reflect heat from the iron exhaust manifolds.
Ignition timing with iron heads and Mancini Racing Mopar electronic ignition package. Ended up at 16* btc idle and 38*total. I tried 18* but this caused hard starting when the engine was hot. I want to try a little softer advance spring, to bring more mechanical advance in earlier.
Air fuel ratio is 13 idle, 14-15 at highway cruise, and 12.75 at wide open.
Blocked off the intake manifold heat cross-over. This helped keep the intake manifold and ignition coil cooler. I considered moving the ignition coil to the inner fender, but still need room for a fuel pressure regulator.
The one inch thick carburetor spacer “ribs” did not line up very well with the minimal flange width on the Edelbrock DP4B intake manifold. A slight leaking was found at the mid span of each side of the spacer/gasket. RTV silicone sealed the problem.
With all my worries about coolant flow...engine sits at 175-185 degF, no issues at all. Had to install an OEM mopar temp sender to have the temp gauge read correctly...a napa one read way too high.
Carburetor jetting….Edelbrock AVS 800 cfm for 5200 foot elevation, no heat Xover.
Primary jet .107, second jet .104, meter rod 7342 with pink rod springs, secondary air door 1 ¼ turn on the tension spring. Accelerator pump nozzle .038. 7/16 float setting with 1 1/8 float drop, idle mix screws out ¾ turn. A square and ½ of the transfer slot showing with throttle plates closed to idle setting.
Widened the idle circuit transfer slots from the out-of-box .029 inch width to .031 inch. Hand cut with drill bit in pin vise… it cuts quickly so doesn’t take much effort to work up/down the slot.
