Starved For Fuel?

[VintageMusclecar]

First check the float levels.

Next, check/replace the fuel filters in the float bowls.

If the car sits for extended periods, you might check to see if the sock in the fuel tank is getting clogged or varnished up.

Eric

[Thomas]

I thought I had found the problem. The rubber fuel line which runs from the solid line coming from the tank to the fuel pump seemed a little long and appeared to have developed a slight "kink". It came as part of the fuel line kit that I installed over 10 years aago, so I never paid much attention to it.
I replaced it with a new and slightly shorter piece.

It took the car for a spin, and here is what I've found. The car "runs out of steam" somewhere around 4700 RPM, in any gear.

I have checked the float levels and they are okay.

Any ideas?

I was thinking of increasing the jet size in the carb.

Or...

Could it be an ignition problem like a weak coil?
The timing is set to 4 degrees and the dwell is 28 degrees

[69L34M20]

It isn`t the jets. How about the valve springs? Try testing them for pressure.... may be float city... which could also cuase a backfire.

like someone mentioned....are you sure the secondaries are fully opening?

[mfchassisworks]

What is the fuel pressure during a run through the gears?

[Thomas]

[ QUOTE ]
What is the fuel pressure during a run through the gears?

[/ QUOTE ]

There is no easy way for me to plumb a fuel pressure gauge into the stock fuel line setup, so at this time this is still an unknown.
I may have to figure out a way if all else fails.

[Thomas]

[ QUOTE ]
It isn`t the jets. How about the valve springs? Try testing them for pressure.... may be float city... which could also cuase a backfire.

like someone mentioned....are you sure the secondaries are fully opening?

[/ QUOTE ]

The engine was completely gone through shortly before I bought the car. I do realize that it is difficult to judge the quality of someone's work when the engine is buttoned up, but I find it difficult to believe that the valve springs could be an issue with less than 10,000 miles on them.
However, I have learned to never say never.

How would I go about testing the secondaries on a vacuum secondary Holley?

Just for the record, the people on this site have provided some great advice so far.

[Chevy454]

[ QUOTE ]

It took the car for a spin, and here is what I've found. The car "runs out of steam" somewhere around 4700 RPM, in any gear.

I have checked the float levels and they are okay.

Any ideas?

Could it be an ignition problem like a weak coil?
The timing is set to 4 degrees and the dwell is 28 degrees

[/ QUOTE ]
Check to make sure your coil isn't wired backwards...car will still run, but takes a dump when under load.

[ssscamaro]

fuel filter in bowls if still equipped.
Float levels!! Does the carb have secondary jet extensions? If so it MUST use a notched float. I had a 69 camaro holley carb without extensions going 1080s 124 put jet extensions in it and fell on its face 900 or so feet. the rear float couldnt drop far enough to let enough fuel in to replenish what was being used. Put in notched float( i always run my holleys with fuel right up to bottom of sight plugs and just a littel tricle if you bump the fender)set level and 1 tenth better 60 foot and 1070 127 mph...
Ryan

by the way i Have a stock Y block that i drilled and tapped for 1/8 npt on the bottom side. ran my fuel pressure guage in it a few times to see what WOT was reading. after i was happy with that took off guage and put a 1/8npt plug back in that you cant see unless you take Y block off.

also i have seen the old fuel sending unit 'socks" melt into mush with age...did that get replaced??

[69L34M20]

You mentioned it is a vacuum secondary..... Take a peak at the secondary spring. The real heavy ones will never allow the secondaries to fuly open. Try a trick kit and put in a yellow one....it opens fast and all the way.

[Lynn]

First:

What Eric said: "Next, check/replace the fuel filters in the float bowls." No one on here knows Holley carbs better than Eric.

Then, what Eric said next:

"If the car sits for extended periods, you might check to see if the sock in the fuel tank is getting clogged or varnished up."

It is a classic case of fuel starvation. Replace fuel filters first. If problem persists, remove the fuel filler cap, then remove the fuel line before fuel pump and blow a small amount of compressed air (too much and you could blow fuel up and out of the filler neck) which will dislodge any thing clogging the sock. Re-assemble and take it for a spin. If it is "fixed" then you need to remove the tank and the tank unit and either clean or replace the sock. Blowing back through it is only a temporary "fix".