Carb / fuel problems

[jreed1978]

Folks,
I have a 64 Chevelle with a 509ci motor, 1150 Dominator, 460 gph PE fuel pump/filter combo, 12AN fuel line to a BG 2 port regulator, 12 gallon cell with foam.

Problem is the car acts like it's running out of fuel at idle and cruise speeds and wants to stop running. I've had the carb apart, cleaned it from head to toe and don't see any obvious problems. Also checked the fuel filter and it was spotless. Fuel pressure holds steady @ 7 lbs. Car runs fine at WOT.

I had a similar problem with another car and the rubber in the fuel line had come apart and blocked things up. I'm looking for some ideas of things to check before I rip the fuel line out of it. Could the foam in the cell have broken down and caused a block? This shit is putting the clamps on my racing and cruising for the year.

Any input would be awesome. Thanks!

http://i93.photobucket.com/albums/l64/jreed1978/Chevelle1.jpg

[Chris Uratchko]

Josh,

i don't see how it is a fuel restriction if it runs fine WOT.

Is this something that has happened recently, or was it always like this with that carb?

[jreed1978]

Josh,

i don't see how it is a fuel restriction if it runs fine WOT.

Is this something that has happened recently, or was it always like this with that carb?

Actually, I freshened up the motor a few months ago, put it in the car and it's done it ever since. I probably should have mentioned that before. Sorry. The carb has always run flawlessly till I re-installed the motor. The motor ran faster then it did before the freshening, so I don't know what to think.

[jreed1978]

Oh and it seems to be getting progressively worse. Could it be a vacuum leak? I've checked for one but who knows.

[Dr. Detroit]

Does it idle ok??? 6psi on the line???
Rockers too tight??? Or Leaky valves?? Bad cam??? Vac Leak???
Look at HG..see if gauge is pulsing widely @ Idle..or very low HG..no signal to carb.
Also weight springs or vac in distrib??

If it idles ok and works WOT..not the carb.
Need more info about setup...

:) Nice Hot Rod...

[jreed1978]

Does it idle ok??? 6psi on the line???
Rockers too tight??? Or Leaky valves?? Bad cam??? Vac Leak???
Look at HG..see if gauge is pulsing widely @ Idle..or very low HG..no signal to carb.
Also weight springs or vac in distrib??

If it idles ok and works WOT..not the carb.
Need more info about setup...

:) Nice Hot Rod...


Sorry for the lack of info. It's been a while since I've messed with the thing. No, it won't idle when warm. But will snap from 2-4k rpm instantly. Has 7 lbs of fuel pressure all the time.

Distributor is locked out @ 38 degrees.

What do you mean by HG? Excuse my ignorance :rolleyes:

Thanks for your time.

[Dr. Detroit]

Sorry for the lack of info. It's been a while since I've messed with the thing. No, it won't idle when warm. But will snap from 2-4k rpm instantly. Has 7 lbs of fuel pressure all the time.

Distributor is locked out @ 38 degrees.

What do you mean by HG? Excuse my ignorance :rolleyes:

Thanks for your time.
HG..Inches of Merc..Vacuum...
If ya think intake is leaking, at Idle...grab a propane torch turn on low not lit or start fluid run it around the intake if RPM goes up..Bingo!
I am assuming you checked the floats, idle mix, timing all the regulars...
I am still thinking cam time or valves tho...since you said carb was fine in the past.

Anyone one Else???


Let Us know..Good Luck...

[jreed1978]

I've checked the carb out pretty well. Have also done the vacuum leak check with brake cleaner. But I'll spend some time tomorrow and go over everything again. Will also check the vacuum.

I'm hoping it's not the cam timing or valves. The guy who helped me assemble the motor is a perfectionist and builds lots of high $$$ stuff. But I guess stuff happens. Would the motor perform so well at the track if the valves were leaking or lash was off and cam timing was off so bad?

I'll keep you guys updated and more input is definitely welcome.

[Chris Uratchko]

Josh is this a different camshaft than before? It's possible that the signal might just be stronger on the idle circut and be a little sloppy.

[jreed1978]

Josh is this a different camshaft than before? It's possible that the signal might just be stronger on the idle circut and be a little sloppy.

It's the same cam I ran before I cracked the stock 502 crankshaft :)
Just a plain jane .722 Lunati roller.

Maybe I'll attempt adjusting the carb tomorrow if I don't find any obvious problems. What adjustments would you recommend I make?

[Troy Patterson]

There are a lot of possibilities for this synptom.

It sounds like a tune issue in the carburetor. Perhaps the cam is installed in a different position or the freshened motor just wants more fuel low in the rpm range. Was the distributor locked out before? What sort of duration on the cam?

How many turns out are the mixture screws?

Troy Patterson

[jreed1978]

Guys, I actually got it figured out... Troy, you hit the nail on the head. My cousin helped me when I installed the motor and he had the throttle linkage all f*cked up. Basically the carb was opened up a good bit at idle and he had made changes to the mixture screws to compensate. I'm really surprised it ran at all. Now it runs like a top.... Idles perfect and runs great. Thanks for all your help. It is appreciated.

[Dr. Detroit]

Ah..Good Deal...I hope it is smoking for ya.
Have fun...