Starved For Fuel?

[Chevy454]

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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

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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".

[BTL]

Just a thought, is the air cleaner clean?

[Thomas]

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Just a thought, is the air cleaner clean?

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Nope. That is clean.

[Thomas]

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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.

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At the recommendation of the performance shop I deal with, I removed the filters and am running without them for testing purposes.