hi guys i installed a innovate wide band air/fuel ratio gauge to see whats happening with my car at 5000rpm.
as suspected its leaning right out to 18:1 at 5000rpm and starts breaking down. cruise ratio is 14:1 and around 4000rpm its 15:1.
now im thinking the fuel pump is to small.
its a 383 dont know what cam, 750 dp mech secondary holley, idle fuel pressure is 4 psi.
its running aftermarket standard mecahnical fuel pump to 3/8 barbed filter then line into carby, which then holley has its own filters at inlet.
all is clean.
if i put a elec fuel pump on, will running higher fuel pressure help with starvation or will i have to increase fuel hose size for flow?
i did read holleys should run at 6psi.
I pulled my hair out trying to make a high output mechanical pump when I put a 440 in the car. I ended up installing an electric pump at the tank. That fixd my problems.
Bottom line is that you need to have a fuel pressure guage to diagnose the problem. I ended up installing an electric Autometer but it was almost $250. Until I put the electric one in, I tywrapped a mechanical gauge to the windshield wipers. After it warmed up I was at almost zero pressure under heavy load. Now I am at 6 psi +/- 0.5 psi.
As far as AFR, I also run a 750 Holley DP on my 440. At idle I am at 14, part throttle cruise around 13.5 and WOT 13.
What year is your car? Do you have 5/16 or 3/8 line?
67 coronet 440, i have 3/8 o.d fuel line.
i bought the holley blue pump but was turned away as it says must be gravity fed and i dont want to cut into the tank.
i have ordered a facet style pump, which i was thinking of running to start with to see how it goes.
ok great i will see if i can get a gauge hooked up, its defenently losing fuel under load.
what does your engine rev out to?
i am interested to see what i can take the 383 to once i fix this fuel issue.
And engine went to 6000 rpm. Ran 13.300 at 102 mph. The combination has been retired as of last Friday night. Car is going back to stock and I will be reinstalling the original tank and fuel pump.
10-25-15, 02:54 PM (This post was last modified: 10-25-15, 02:58 PM by 67440Dodge.)
Jpr777 Wrote:I ended up installing an electric pump at the tank. That fixd my problems.
how did you install it, cause holley want it gravity fed and my pickup is in the top of the tank.
I don't have any pictures of the installation, but if you look at this picture, the pump was mounted on the right frame rail (the 2 large screws are the old mounting holes), and ran solid line to the tank, with just a small piece of rubber hose to connect to the fuel pickup. Then it was solid line all the way to the engine compartment and up to the regulator.
7372
It worked out pretty well. If I ran against Mark's daughter's car, I'd be at the end of the shutdown lane chugging a waiting for Mark to show up
I love Mopars so much I'm date coding the skid marks in my underwear.
You said around 5000 rpm it starts breaking down...... What do you mean by that? It starts breaking up or missing?
You also mentioned that you don't know what cam is in it. Has the cam been replace to a performance one while still using the stock valve springs?
This could cause the valves to float and make a miss fire condition / breaking up, showing a very lean condition on a air/fuel ratio meter.
If your friend Jack helped you off a horse....... Would you help your friend Jack off a horse?
waiting for Mark to show up 
