Took the nova out yesterday and it smoked like hell.I mean city block long and you could smell oil.Turned out to be the e-vac was sucking the oil thru the exhaust so I had to install breathers on both sides to stop that which i should have known better since my chevelle had this set-up.Also, the carb was loading up so bad that the gas fumes would burn your eye's to the point you had to walk away.I changed the power vavle which seemed to help but I found out today it did'nt really help so i went back to the 1st power vavle which did'nt help.Keep in mind this carb was ordered and built for this set by BIGS,it's a 950.Noticed the fuel pressure changes a lot and the only thing i can think of that is causing the carb to load up this bad is no fuel return line back to the cell?The fuel pump is a BARRY GRANT 400 and i have to screw the adjustment all the way out to get the fuel pressure to start to drop below 9psi.Any thoughts on this guys?BILL,THANKS

Is there any adjustment on the pump like a Comp140 ?

Not sure but I'll look into it!Is a number 6 line big enough for a return line or should I go to a number 8.The reason I ask this is because there is a number 6 already installed on the car but I think it was used for the small fuel cell that was used for nitrous.THANKS BILL

I highly doubt a #6 is large enough for a return for a BG 400 pump.

I have a Comp 250 and when I originally built the car, I used a #10 feed & #8 return using a 3 port return style Mallory regulator...same issue you described. I could not set the fuel pressure down. As I found out from Mallory tech, the fuel was backing up in the return line. I changed the #8 out for a #10 and finally got the adjustment back.

I believe your return is from the pump back to the cell? If so, I'd check with BG on their recommendation. I'd lean towards using the same feed & return line sizes...either #8 or #10.

Keep in mind that in all your driving situtations other than WOT, your likely returning 90% of the fuels pump supply back to the cell.

That is what I was thinking but a buddy said that line was big enough and I had second thoughts about that.I thought like you said about in and out being the same size.You know how it is when a friend puts in his $2.00 worth.Thanks I'll go the same as the in line.BILL

I think a pan evac system that plumbs to the headers is a NO NO on a car with a full exh. In fact I've seen it be a NO NO on even cars with flowmasters right after the headers.
Requires a totally unrestricted exhaust, and requires that the tubes in the headers are installed correctly.

For the fuel system, Mallory stated very clearly that the return line needs to be as big as the feed line. Otherwise the fuel pressure will read wrong. You will simply end up measuring the pressure in the return line. Think about it, with that huge pump, you are returning most of the fuel to the tank at low engine speeds.
Also, the return line needs to be above the fuel level, not at the botton of the cell.

Personally, I think the return should come from the regulator located near the carb, but BG makes pumps that return right from the pump.
Of course, BG says you need 400GPH to feed 500hp.....but that's another story.

Ron

10-4 on all that.I was going to run the return from the top of the cell to the reg-did'nt know a BG was set-up or had a built in deal to return thru the pump.As far as the exhaust it can't have much restriction being it's 5 inch.Once i get the carb deal worked out I'll be running the car to make sure the e-vac is'nt still causing a problem(such as burning oil.If still a problem then I'll go to plan B. Thanks for the help!BILL

I missed the 5" exhaust part.....that ought to be PLENTY big! :-)
Ron

See, now I would have done that wrong.

I had -8 from the pump to the regulator and -8 back to the tank and STILL couldn't get a handle on the pressure on my racecar. The return line run is 12 feet long with only 2 straight fittings.

The way to check for a return line problem is this: Loosen the regulator ALL THE WAY to as low a presure as you can get. If you can't get the pressure to come down to 3 (three) psi or less, you have too much restriction in the return run and you're going to have fuel pressure control problems. You'll need bigger I.D. return line and fittings that have less restriction to cure the problem.

I ended up with -8 from the pump at the fuel cell to the Mallory 4309 regulator by the carb and -10 back to the tank.

I can get the pressure down to less than 2.5 psi now and all my fuel control problems went away.
Car went 9.30's @ 144 with this setup on a N/A 355" with only 7 psi at the carb on alcohol. It never varies more than 1/2 psi now and never runs fat or loads up.


Randy