I haven't taken the time to read every comment or reply but let me says this ! You are in no way over carbed, over camed, or from what I see anything else with this build. At this time I didn't see any mention of an aftermarket Distrib. if you are using a stock type igniter, YOU NEED to find someone that can run a complete ignition function test on a computer diagnostics machine. You need to find out how much voltage is being dropped at each point in the secondary side from the coil to the distrib- from the center tower to the spark plug towers all the way to the plugs. I CANNOT IMPOSE ENOUGH IMPHYSIS ON HOW IMPORTANT IT IS TO KNOW THIS WITH THESE CARS ! I have run across several instances with Chrysler products where there was an issue with the phasing of the distrib shaft and points cam or electronic trigger wheel to the position of the ignition rotor to the towers of the distrib cap. What happens is this, the ignition timing so to speak is late. The rotor is already past the intended plug tower when the spark should be jumping, so the coil must deliver its maximum output when it should require much less. Under hard acceleration or throttle, the advance diaphragm cannot correct this without modifications to the link arm. This is the point of failure in the system. Once corrected you will find so much HP it will blow you away !!!! I know from experience with one 440 I had and many other peoples engines this to be a problem. Again what happens is the spark is coming according to the setting of timing but it is at a time when the rotor is pulling away from the plug tower on the cap and you have lost proper relation to the complete timing cycle for ignition and all the potential current to lite the fire when it needs to be lit. A timing light will not tell you what you need to know here ! By looking at the burn marks on the rotor and cap you will see that the arc marks are all the way to the trailing point of the total picture when they should be on the leading point so when rpm increase, there is a much shorter path to cross giving the coil the ability to build much lower required voltage thereby having much higher reserve under compression( which requires much higher output) under load. You actually get what is a massive amount of basically misfires which you cannot feel. That 440 I mentioned was not a stock engine and would barely lite the tires in a Barracuda before I learned what was happening by putting it on a scope myself in a shop I worked in back in the mid 80's, once I saw what was happening with the distributor and corrected it, it would smoke the tires for the whole 1/4 miles both sides and gaining speed all the way past 110 mph running 2.76 gears of course the speedo would be barried so the 110 was from the dragstrip clocks. Before doing the distrib to after, I had to have found at least 200 HP on that engine that was just not there. I couldn't believe it at first, the car was such a dog and I was so disappointed but after, it was a monster awakened. Trust me on this please. Do the test and confirm first , that the ignition system is completely in phase. You need to have a coil voltage output of less than 3,000 volts from the center tower to the plug towers of each wire than less than 1,500 volts dropped in the plug wires to the plugs so you can still have minimum loss of output building arc across plug gaps. With this, your coil will have high margin for output under max load to fire the plugs. Please do this testing before spending any money looking for a reason for low power production PLEASE ! I had a 318 before I got the 440 and I didn't have the scope to test the ignition system but that engine I built with a lot of factory parts from various SBM options and ported the heads, installed a thermoquad intake and carb from a late model 340 which gave me a learning curve and I raced it against all comers and nearly got in many fights about whether it was actually an 18er. People swore I had altered the numbers and it was actually a 340 or 360. It was amazing how it ran. I shut down LT's W30's Clevelands, you name it, I even shut down my share of BBC's with that little motor. I truly regret that day I let that little motor go down the road in someone else's car, a 72 roadrunner that had a 400 in it that didn't run. I gave up my trans along with the 18 for all the parts from the RRr with plans to build that BBM and never got it finished before going to a 440 that ran but was worn out. Every time I worked on any MOPAR or any other engine after that with a Distrib. I always checked the shaft and rotor phasing to be sure it was lighting on the lead cycle instead of the trailing so there was no suspected loss of ignition causing loss of power. I do not believe in over carbing any more especially with secondaries that require any vaccum to open which is pretty much all of them except Holleys. Over camming is another issue. Please check that distributor. Please check that Distributor! It will not cost you anything more than some time and diagnostic fees. I promise you will find some HP hiding under that cap, than if you still have doubts, you can go on to the next level which I doubt you will need to anyhow. Any 340 can make nearly 350 HP tuned right with near stock parts ! EVERY engine can make more power tuned RIGHT and that means getting the ignition right first then looking at fuel and other places.
