A guy I know approached me tonight asking for help with a problem with his Hemi Dart. It is breaking down at 4500 rpm. To date he has changed the ignition box and plugs and plans to change the wires (not installed yet) and possibly the coil. The car is the Hocus Pocus Dart that was campaigned in Canada as a bracket car and then converted to a street car with a crate 426 Hemi motor using the MP cross ram and original Holley carbs (I'm guessing the jetting may not have been changed since it was raced). I haven't looked at the car yet, but since we run a wedge I'm looking for some baseline numbers on what this car should have.

I want to check the rotor/pickup clearance in the distributor, the type of plugs (will running the washer on a Hemi plug recess it too far in the combustion chamber?), coil, fuel pressure, and jetting. The main things I want to know is what would be a good plug/heat range to run in this engine? What baseline jetting for the dual carbs (main & metering plate)? Unfortunately, the original owner passed away just as he completed the car, so there isn't much info other than what I stated above. Thanks for the help.

Jon, I use Autolite AR51's, or else NGK BP8ES. Right now, there are 84 jets in the carbs. I generally don't run the washer, although have left them on by mistake and never noticed much difference.

Thanks Steve. The stock crossram carbs should have a metering plate on the secondaries. I'm wondering if they were drilled out. Do you know what plate would have come with those carbs?

I don't know what plate it is, Jon, but you can only jet the primary side of those. There are no provisions for secondary jets. When you say it's breaking down over 4500 what exactly do you mean?

Steve,

Breaking down, popping at about 4500. He said letting off the gas slightly will let it smooth out and pull to 6000, so I'm thinking it may be a carb problem. I haven't looked at the car yet.

The secondary metering plates were a fixed jet based on the drilled passages. I believe you could get different plates and most racers either drilled the plate to suit their needs or installed small removeable jets.

Yeah, some guys did. I don't know that it would change much....I know the only guys who seem to mess with them are SS & Stock guys, who aren't permitted to screw with 'em, or dinosaurs like me who are too old and blind.

It does sound like a carb problem, though....are you sure there isn't a vaccuum leak somewhere? There is a lot of places for something to suck air in those....any smoke?

Not sure if there is a leak. Will check. Haven't looked at the car yet. I did find some info on Holly's website that the baseline primary jetting is 80, 6.5 power valve, however they don't mention the secondary metering plate.

We have issues that we need to straighten out with our car first, so this will have to wait.

I know what you mean about eyesight...

Thanks,

The secondary plate no. is #12 which is equal to around a 72 jet size. We now use plates that we can use a holley jet. I use quick fuels plates.

Mine were almost perfect out of the box. The only change was going from a 65 PV to a 35. You may want to check the linkage for over-travel.

you can redrill the sec plate-one of the tricks in the old Chrysler books for big roller cam. popping- simple, you're running out of gas check the pump and lines for restrictions-those mods to the plates and primarys will suck some gas.ask me how i know.

Thanks for the replies. I'll probably see him tomorrow at the morning cruise-in at Burtonsville's Church of the Holy Donut (there's a story behind that).