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Discussion Starter #1
Let me start by saying I'm happy with my new carb (Quickfuel 680).

Installed yesterday and it didn't require much adjusting at all. It ran good in and out of gear. In park idle was set a hair high to account for it dropping in reverse. There was no air cleaner on it. Today I install the k&n air cleaner after getting the right height and it drops even more. The car wouldn't seem to idle smooth until I ran it about 5 min and drove it a few miles. I got home, shut it off and no run on.
So...does an air cleaner 1.25 drop base, 2.8 height element and Xtreme lid really affect idle like that? Also, should it take that long to warm up too a smooth idle? What adjustments can I make?
Yesterday it was making 17 on vacuum guage.
 

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The air filter is a restriction. Make your adjustments with it in place. The 4" X 14" air filter on my car cost me 12HP on the dyno. :beers:
 

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Discussion Starter #4
It could be the "Xtreme lid". I recall reading these flow through lids actually create unwanted turbulence in the air as it is entering the carb.
Hmmm, I hadn't heard that before. I thought they were good for performance. I'll see if I can find a solid lid to test.

Would the restriction affect the air/fuel screws or can I just bump up the idle?
 

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It's likely a touch rich without the air cleaner, and adding it made the condition worse. Lean out the 4 corner slightly. I have also heard the open element lid can cause problems.

Carbs can be finicky, but once you get comfortable with what they want they are easy to work with. Every change you make to air in, air out or timing effects the tune.
 

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Discussion Starter #6
Ok makes sense. With the taller element I don't think I need that lid anyway. Ill just put the solid chrome lid on and make the adjustments. I had no idea air filters make a difference.
 

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Discussion Starter #7
Is 17 ok on vacuum with power brakes? I think vacuum lines are running differently since adding the performer rpm intake. If I recall correctly the vacuum advance, pcv and trans were connected to the carb. The booster was to the intake fitting. Since adding the Edelbrock, booster and trans run off a tee on intake. Vacuum advance and pcv to carb. Will this affect vacuum?
 

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17 is more than enough vacuum.
 

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Do you have an electric choke ? If the car took 5 minutes to idle a little smoother you may have to adjust the choke for cold start-up.
 

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Discussion Starter #11
Yes it has an elec choke. It was also suggested I lean out the 4 corners. Is leaning outward (counterclockwise) on the screws? Is that adding air or decreasing air? I assume adding. Not sure I'm clear on rich/lean. It ran great before adding that k&n element and extreme filter type lid. I'm for sure going to a regular 14 inch lid.
 

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Yes it has an elec choke. It was also suggested I lean out the 4 corners. Is leaning outward (counterclockwise) on the screws? Is that adding air or decreasing air? I assume adding. Not sure I'm clear on rich/lean. It ran great before adding that k&n element and extreme filter type lid. I'm for sure going to a regular 14 inch lid.

Tightening the screws leans it out, loosening them richens the mixture. I have heard it described as being like a water faucet, unscrew is open the flow, tighten is close the flow (of fuel).

How many turns out are they now? If you do lean it out go about 1/8 of a turn to start, all 4 the same. Biggest thing is one change at a time, then test. You can get a perfectly good carb really screwed up with too many changes at once.

If it's an idle issue only, it probably can be resolved with the 4 corner.
 

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Discussion Starter #13
It seems to idle ok in park. It was mainly in reverse that it jumps and drops way down like it wants to shut off. The gen light even came on.

I'll try running no air cleaner first just to test. Then add the 2.8 k&n element and solid lid to test. If still doing it, I'll leave the filter on and try doing the lean adjustment.

It was fine with no filter when first installing the new Quickfuel carb. I had to order an element and needed to know how tall for clearance I borrowed my neighbor's Edelbrock air cleaner with a 3 inch paper filter and chrome led. Then I went for a test drive and it was right on the edge where if we dropped idle it would die and if we increased idle it was too high. Perfect was just a hair high.

Then I give my neighbor's unit back to install my new element and xtreme lid I guess pushed it over the edge.
 

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Discussion Starter #15
Great read!

Where it talks about poor levels of adjustment and erratic idles...it mentions running vac advance directly to manifold vacuum.

My vacuum advance is running to the carb. I have a tee split between brake booster and auto trans. Should I switch where I have the trans and distributor vac advance? Does that matter with a mild cam or just stick to leaning the carb a bit?
 

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Personally I would adjust the carb. Warm it up first and tune it the way it will run with the air filter on. If you can get your hands on an air fuel ratio meter it helps a lot.
 

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Discussion Starter #17
I just tried running it with no air cleaner and without adjusting it. Cold, it wouldn't idle in reverse and backfired twice! It took about 6-8 minutes to warm up enough to act right. It lurches when I put in reverse as if I had a huge cam,etc. any chance my torque converter could be malfunctioning. I assume it is just a stock th350 as it was already in there when I got the car.
 

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Hey Tony just a thought here. I have a K&N also with a drop base. NO change for me with or without the air cleaner. Is it possible you are hitting the linkage or something when installing the drop base ???
 

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Discussion Starter #19
We looked at that and it doesn't appear to be.

I called summit tech and the tech stated I should advance timing and play with air/fuel adjustments. I found out my total is already at 36-38 now. Then he said lower primary jets from 70 to 68 since is a bit too big. Supposedly my cam is the biggest with stock stall. But he said since I went a little big on cam, intake and carb a larger stall would help.

My mechanic is thinking it is actually running lean since timing isn't retarded and it backfired twice. Thoughts?
 

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Do you trust your mechanic? Are you fiddling with the carb after he adjusts it? Welcome to the world of carburetors. They ain't fuel injection! They need to warm up.

Stop and think about what is happening when you screw something out of a passage so it does not protrude into the flow of liquid.

You're using to short of an element on the air cleaner. You're creating too much low pressure with that element and its affecting the idle air bleeds and float adjustment. There is NO way that you can't run a standard 3 inch tall air cleaner element if you are running a drop base.

I hate to see somebody flailing about like this and just throwing part after part on his engine. If you aren't going to or can't trust your mechanic to suss it out, join a local car club or drive it to a local cruise. Ask somebody if they know who the Holley guru is in the area? They'll tell you or they might even help you. You are NOT going to get it tuned over the internet. Read a book on how to tune Holleys (that's what a quickfuel is) and the manual that came with your carb before you touch a thing. Understand the idle circuit, the power circuit, how and when secondaries tip in. You appear to like the internet, here's a link: http://www.junkyardgenius.com/holley/tune01.html Good luck.
 
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