You said
Carb should be good. I used a edelbrock 650 first and now this 750 willys and same problem. My timing is at 14 before top dead center and was up further but it had a hard time starting that high. It does fine when you first stomp it but sputters out after its initial squirt. I will have to check in line filter, I have two of them on it one before and one after the pump. Everything is new as far as that goes. 2 brand new in line filters, new holley blue pump, and rebuilt carb. Vacuum advance isn't hooked up right now. I had the same problem hooked up and not hooked up. Not sure where would be a good place to hook to because the ports on the carb have vacuum at idle. I will have to check for vacuum leaks.
And you said
I just had a thought will slant 6 factory line be too small on a v8 360? I upped my fuel pressure to 6.5 pounds. I went out and drove it. If I stomp it just in the primaries it would go like hell for around 5-10 seconds then sputter. If I got back in it right away it'd continue to stumble. As soon as I would stop as if to let the bowl fill up the car would go fine again like a bat out of hell until it would seem to run out of fuel again.
It's not a vacuum leak; you said 21 pounds, I'm assuming inches
It's not ignition timing; you said 14 initial
It's not the ignition system; you said plenty of spark
It's not a squirter issue; it takes off hard when you slam it down
It's not a PV issue; you said it runs 5 to 10 seconds before powering down
It's not a fuel level issue; it idles pretty good
You said
It drives for 5 to 10 seconds at WOT, then sputters and acts like it has run out of fuel .
dhunt said you are running out of fuel, and I agree.
The carb does not run on pressure. It runs on volume .Your pressure regulator stops the fuel from flowing until enough pressure has built up to pop the control valve off it's seat, then a little fuel sneaks by, the pressure drops and the valve trys to slam shut.This happens on a continuous basis, and the gauge reads an average, of what you have set it to. You could have a hundred psi there, and if it is pissing thru a little tiny hole in the float valve, you will run outta gas as soon as the bowl is empty.On the other hand, if the pump can deliver twice the required amount of fuel into the bowl at 1 psi,that is just fine too.
OhOh I think I see lights flashing!
Yeah thats right,I agree with
Dhunt;you are running outta gas. The trick is why. Here are some ideas, from the carb backwards;
float-valve orifices too small, fuel filters too restrictive,restricted line from the regulator to the carb, faulty regulator, faulty pump, faulty supply line to the pump, restricted pick-up.
You can eliminate almost all the variables by doing a volume output test, right at the carb. If this tests sufficient, then the only variable left is the float valves themselves. To test those, you will have to calculate their total area cross section, and convert that to a single hole size, then fit a correspondingly sized jet into the end of your test apparatus, and re-run the volume test.Your system will have to deliver 1/2 pound of fuel per horsepower per hour. This converts to about, lemmee see; I get 17.07 ounces per 100 hp per minute, or a little over 1/2 quart per minute,per 100 hp; Ergo;At 250 hp, you will need about 10.67 ounces for 15 seconds.
I would plumb the regulator at the end of the line, after the carb,with a return to the tank; which would eliminate it as the problem. IMO deadheading the regulator is a bad idea.
Now I do see a few other issues.
The first issue, And my pet peave,is the T-port sync. If you set your initial timing to the highest vacuum, what almost invariably happens is the T-port gets outta sync with the idle discharge ports. This leads to bogs, sags, hesitations, stalls on putting it into gear, poor tip-in response, and ugly gas mileage; just all kinds of frustrating chit.
The second is the accelerator pump system. The squirters have to be responsive. They have to squirt, capitalS Squirt, the instant the throttle is touched even the teensiest, and the squirting needs to continue un-interupted for a good long time as the throttle continues to slowly rotate open. No dribbles, no hesitations, just pure squirting going on.If it doesn't, you will have driveability issues.
The third, don't forget to limit the power timing so you don't hammer the engine to death. Typically our Iron headed monsters will only require 34ish degrees at 3400ish. More or earlier is not necessarily better.
Fourth;You are correct in leaving the vacuum advance disconnected for now.
And finally, some engines do not respond well to running 2 foot straightpipes,off the logs, especially as the cams get bigger.I wouldn't spend a lotta time on this until the exhaust is finalized.
I reserve the right to add more as I may think of it, unless it repeats something already said; then you can slap the Alzheimers outta me.
