my holley has no top end - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 9 (permalink) Old Feb 19th, 02, 09:22 PM Thread Starter
 
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My holley is driving me crazy. I have cleaned it, Adjusted the floats, checked the power valve, and changed the cam on the acc. pump. Sometimes it will idle perfect and other times it will flood very bad. Last night it was flooding so bad that when it wouldn't start, I got out & looked at it and it had gas about an inch deep on top of the butterflies. I banged on the front bowl and got it to stop. Engine finally started. The biggest problem is that it has no top end.It runs like a scalded dog from 1/4 to 1/2 throttle, but when I floor it & the engine gets to about 4000 rpm's it has no power!! Then, after I let off of it, I can feel it trying to foul plugs. What in the heck is wrong with this thing??? Please help. Oh yeah, I adjusted the air screws too.
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post #2 of 9 (permalink) Old Feb 19th, 02, 09:37 PM Thread Starter
 
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Oh yeah, It's a 750 dual line with vacuum secondaries.
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post #3 of 9 (permalink) Old Feb 20th, 02, 03:20 AM
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install a tighter spring for the secondaries, (yes it sounds weird, but the softer the spring, the harder it makes it to open the secondaries. and it sounds like you screwed up your mixture, do 1 side at a time, turn them in untill it runs like $hit, then back it off just a bit,

but the flooding problem sounds like you screwed up the rebuild, Sticky float, or float with a hole in it..

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[This message has been edited by Chris Edwards (edited 02-20-2002).]

[This message has been edited by Chris Edwards (edited 02-20-2002).]
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post #4 of 9 (permalink) Old Feb 21st, 02, 02:50 PM
 
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sounds like a float problem.
pull the float bowl and hold it upside down.
it should be relatively close to level to the
ground as a starting point.
could be a hole in the float.
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post #5 of 9 (permalink) Old Feb 21st, 02, 05:05 PM
 
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The dripping could be a stuck needle and seat. I bought a perfect rebuilt 4010 off ebay but after less then an hour of running the secondaries started to drip, uhg
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post #6 of 9 (permalink) Old Feb 22nd, 02, 03:04 AM
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I just went through a similar problem with my front bowl flooding like mad- in my case it turned out to be the small spring under the float had come off of its seat. I re-seated it and cured the problem.

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post #7 of 9 (permalink) Old Feb 22nd, 02, 03:44 AM
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you didn't say what fuelpump... if elect. regulate to 6-7psi, stock pump should be fine.and above statements sound like good starting points.

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post #8 of 9 (permalink) Old Feb 23rd, 02, 03:38 AM
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Chris - it sounds weird because it wrong. Use a LIGHTER spring to open the secondaries quicker NOT a STIFFER spring. KC2000 If you don't know who to believe consult the Holley literature to confirm.

The spring acts against the diaphram and the diaphram is connected to a rod that opens the secondary throttle blades. The diaphram is pulled up (against the spring) by a vacuum signal that comes from the primary venturi pick-up. The check ball in the diaphram housing "blows off the seat to remove vacuum from diaphram chamber" when you let off the gas. [Holley Carburator Handbook 4150 & 4160 Selection Tuning and Repair, Mike Urich, HP books]

Also, if your carb is too rich the engine will "load up" and IMO this is most noticeable when in high gear. An engine can overcome an overly rich condition more easily in lower gears because the engine is increasing revs at a quicker rate.

The very first thing I would do is change the power valve - a blown power valve could cause the symptoms you are experiencing. While you have it apart, make a note of what size jets are installed and inspect the needle and seat to make sure there is nothing getting caught in it. Then, when you get it back together set the float levels. If you have an electric fuel pump make sure pressure is regulated down to 5 - 6 psi.

If this doesn't fix it you are probably "barking up the wrong tree." The problem could be caused by a vacuum leak or an ignition problem too.

Hope this helps.

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[This message has been edited by Eric68 (edited 02-23-2002).]
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post #9 of 9 (permalink) Old Feb 24th, 02, 07:45 AM Thread Starter
 
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Thanks all. I rebuilt it & it's fine now. It is in a '87 s-10 blazer. I like camaros too.
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