Reverse fuel flow on CAT ?

I don't like the idea of removing the hand primer. Interested to see what Mr. Haney and some of the other cat guru's have to say about this.

 

They remove the hand primer because they are a culprit for sucking air, plus flow restriction

 

That hand primer design always seemed pretty similar to what mercedes was drafting back in the 1950s. They were always prone to fuel and air leaks. Bosch came out with an upgraded primer that solved the leak issues, but I don't think it did anything to resolve constriction concerns.

 

i don't think it matter's to much witch way the fuel flow's though the head i think they feed the back of the head because they can get a bigger fitting there i was thinking about doing some thing like this myself them little steel line's can flow only so much fuel

 

I belive the the lines are a certain size to keep the fuel pressure up so it really shouldn't make a diffrence which side of the head the fuel goes in

 

Yeah I think its the same thing, the fitting size

 

So with a stock engine is this even worth the time and money?

 

The reason for changing the fuel flow direction is the CAT steel supply line from the fuel junction block to the cylinder head is a # 6 line. The reason CAT went with a steel supply line in this area is the heat from the engine was destroying hoses in the earlier 3406E model engines in 2-3 years. A lot of times this hose would split while the truck was being driven and the driver wouldn't notice it immediately, causing a major fuel spill covering miles of roadway.

When doing this upgrade all the supply lines are upgraded from # 6 to # 8 which is 3/8" ID to 1/2" ID. The supply is upgraded in diameter, but the return stays the same size. Where CAT fed the supply into the front of the head is in a very tight area to work and you can't install the larger # 8 hoses and fittings very easily. By keeping the stock # 6 steel line in place, you accomplish two things. One is it makes doing this conversion less expensive to do. Two is the steel line is kept in place to avoid the problems of the heat destroying the hoses and causing a fuel spill.

You may think that by not increasing the diameter of the factory steel line that what is the purpose of doing the upgrade? You have increased the line size to the fuel rail in the head. The engine will pump more fuel in volume from the head to each injector. As the fuel passes each injector there is less fuel in volume to be returned to the tanks, so the # 6 return line doesn't need to be upgraded. This helps maintain a constant fuel pressure from the entry of the fuel into the head, until it exits the head when the engine is at full load. So each injector should have the same fuel pressure along the fuel rail to fill them each consistently, whether it is the first injector in the fuel rail or the last one.

The primer pump does cause restrictions. My own truck doesn't have one. If you install either a FASS or Air Dog pump system, you'll have this to prime the engine, unless you run the truck complete out of fuel.

 

Kurt, you say you run with the block off plate in place of the primer pump. Can a guy buy one of these at cat?
Do you also run the 1/2 inch feed lines. What are your views on running a fass or air dog? Do you think they really make a difference.
Thanks for the advise by the way!!