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Discussion Starter #1
hey all,
I'm hoping the brother-hood can save my bacon again. I'm still messing with the 0.030 350 of mine. I can get it to idle at 750rpm with 8* initial advance. I installed the cam 4* advanced and have a rochester 4Bbl, points and TH350. anyway, now i get low vacuum and had to install a vacuum canister. My problem is this; The thing runs like dirt; I don't think there are any leaks. When i accelerate, there is this huge lag and then a pedestrain paced acceleration (i've tried both settings for the accel. pump.). The thing is also a huge emmisions pig. The exhasut smells super rich, though doesn't look very black. Both mix screws are about 2-3/4 out. What is the best way to do a thourough (thurough, therough...good) setup. dwell, mix, timing, idle?
 

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Sounds like you are running a fairly big cam,280 or so.If thats the case? your problem is obvious.A Qjet uses vacume to pull the primary metering rods into the jets at idle.No vacume equals rich idle or no idle.They can be tuned for a fat cam,but I've had little luck doing it myself.Unless you have a lot of patience tuning or know someone who does or is slick on a Quadrajet,I would switch to an Eldebrock or Holley,which are easier to tune.Good Luck.
 

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Gene's right on the mark. Advancing the cam didn't help your low speed vacuum any either.

The correct setup order is dwell, timing, mixture, idle.
 

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Discussion Starter #4
thanks for the replies guys,
I think that reseting the cam would help a bunch, but i'd hate to un-pretty my finally-pretty engine and engine bay.
If i do lean out the carb, do you think it would help any? I'd like to keep an oringinal (looking) carb to get "collector" plates from my insurance company. It comes with a insurance discount of 2/3, prestige and exemption from emissions testing!! ;) Any options for the package i have?
 

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If it smells rich, it probably is. I don't know much about Q-jets, but 2-3/4 turns out on the idle screws is what I call "pig rich" --- at least it is on a Holley. I set mine for max vacuum at idle which is usually only about 3/4 of a turn. With the air filter off I set the screws for max vac and then turn them just a hair to the lean side so the vacuum reading just starts to drop.

A weak ignition will also cause your engine to have a poor burn in the cylinders which will pump out a lot of half burnt gasses. A fresh cap, wires, rotor and plugs couldn't hurt. I think there are conversion kits that eliminate the points using your existing distributor and at the same time give you a hotter spark.

If you get your A/F mix ball-park close and your ignition providing a hot spark and you still have trouble accelerating, you might try a hotter plug. Hotter plugs will stay cleaner and will last longer.

If I had to guess, it really sounds like fouled spark plugs to me.
 

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My 406SB that is about 9.5 to 1CR. and with an RV 280/230, .480" lift cam has a Q-Jet sized for a stock 400 or 403 inch engine AND it will still burn your eye's!!

But once above 2500 rpm or so runs like Jack, the Bear!!

I had a good tuner check it out and he said it was rich down low but that it was right from about middle on up!! Heck, cruising on the hwy at at the time of the 55 speed limit, (or maybe up to 60 mph), it got like 15 to 15.5 mpg so I thought it always was pretty good... pdq67
 

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Discussion Starter #8
thanks for the tips guys. PDQ67, my car sure is an eye-burner. It runs well with some RPM, but it's a dog off the line. It also porduces low vacuum. 12" to the best of my admittedly iffy abilities. Anyway, the plugs, wires, cap and rotor are new. (it's a new build). Unless any of you has a killer idea, i think i'm gonna reset the cam, to make it idle smoother and increase the vacuum. PLEASE COME UP WITH A KILLER IDEA GUYS!!!!
Thanks!
 

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theres a rochester book/bible by doug roe that has made me a quadrajet believer, has tons of tuning tricks in it. a great all around carb in my opinion, just have learn how to tune them.
the book is around $20-25. very worthwhile if you plan on keepin the quad....
good luck
kip
 
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