Hat vs. Port setup

Looks like no one will answer so I will chime in here and see if we can get some discussion going.

To me the larger hat jets are always put forward because fuel from the forward nozzles has a longer way to travel to the back of the blower before it comes out the bottom and has to go back forward again. During this travel a lot of fuel is spread out or lost or used for lubrication. So we put in more fuel up forward to make up for this.

As far as the size of the port nozzle jets would depend on the size of your motor, the type blower (screw or Rootes), the amount of boost and the fuel pressure. A screw blower has less fuel going into the hat and makes more boost so the port nozzles are much larger. With a Rootes you are trying to put most of the fuel up in the hat for cooling while not making the port nozzles too small so they can block up easily. (It is good to run an inline fuel filter or at least put a screen trap in the inlet of the barrel valve because I don't care how careful you are there will be dirt in the fuel tank). Some people run down in the 30's in the ports and can get away with it. I like to go no smaller than 40 just as a little insurance against blockage.

It is hard to get more than 65% of the fuel from the hat nozzles and keep the fuel pressure up.

Lars, if you are playing "what ifs" then it would be a lot easier to use Jetsize software. If you don't have it then find a another racer that does and put your original tuneup in Jetsize with it matching in fuel pressure and hopefully GPM then start swapping things around. Jetsize will keep the GPM to the motor the same so the tuneup will not change while you "what if" it