I recently installed a Ram Jet 502 in my Chevelle and I think I have too much fuel pressure. Factory called for a pump that generates 43-55 psi. I am showing 50 psi at idle and the engine runs pretty fat and eventually loads up. RJ computer has no 02 sensor (open loop)so it can't adjust for the added fuel. Any input would be greatly appreciated. :confused:

Could be a map sensor problem.
Try turning the FP down to 43. Should clean it up some. Also, is your timing correct, TPS set to .5-.7v and the idle up high enough?

Thanks Scott! I'll give it a try. The factory regulator, which is part of the rail, is not supposed to be adjustable but I got around it. I'm not sure if I know how to change the voltage on the TPS. The rich mixture is not a real bad problem but Since I just got the engine running for the first time I'd like it to be prefect.

Hey there! I have a ramjet 502 in a 70 also. I asked everybody I could find for help and ideas when doing the swap planning, and the biggest help for the fuel system was street and performance. They said to use the rock valley tank and fuel pump, and even though its rated at 2 gph LESS than the 35 GPH required by the motor, they said their experiance with modified or stock motors has been great with that pump. I have not had any starvation issues with it either. They told me using anything larger will cause a rich condition at idle, and the fuel cannot return fast enough which makes the pressure go up. Everyone I have spoken with has the same problem. My engine has the oxygen sensor feedback also, but that will do no good in a dead head situation anyways. Are you using a 3/8 return line? What size fuel fittings are you using? I found the street and performance fuel rail adapters were MUCH larger internally which will give a better flow rate. I had some aeromotive fittings that I returned due to the small internal diameter.
One fellow I speak with regularly has heavily modified his regulator to make it work, but he sprays his motor also, so the larger fuel pump was probably a neccessity for him.

you might also ask street and performance if they modify the computer for your ram jet to accept an o2 signal. I think they do or arizona speed and marine does. i know a guy that used one of those companys on a ram jet 350, and he sadi the difference in performance was a lot
Chip

I used -8 Aeroquip on the feed and -6 on the return. The return size on the tank sending unit is only 5/16. I used the Grand National tank and sending unit on the Chevelle.The pump is a Holley 255L pump. I thought it was within the range I was looking for. Guess not! I backed the tamper-proof screw on the regulator out three turns and it got a little better but I'm still at 45 psi. Better than 50 but still too high I think. Should I just bite the bullet and change the pump to the Vortec truck pump recommended in the manual?