86 sports coupe

Did a rebuild on a q-jet I bought off ebay(800 cfm) Checked float level, spent alot of time making sure it was clean. With the car warmed up it wont run without the choke. Right now Im just a 1/2 turn out on the mixture!

five7kid

iTrader: (14)

In = leaner, out = richer.

86 sports coupe

What about holleys?
In leaner outer richer also?

86 sports coupe

Whats a good bench setting to start with?
Thanks Randy

86 sports coupe

Found 1 very small vacume leak, got carb adjusted 4 turns out and it is still way to lean. Only think I can think to do is tear it apart again. The float is used. Had the carb on , had it running and sprayed it down with wd40 to check for leaks.It runs with the choke 1/2 way closed, pulled plugs and they are like new. Idles eratic without choke.

Sonix

iTrader: (1)

This is on your 305? hmm, why get the 800cfm model on a stock 305? (or is it stock?) I've heard over carbbing can lead to a lean signal, as the vacuum signal through the boosters is low (just what I heard, I certainly can't explain that or back it up...)

4 turns out is about normal. What main jets and rods are there? What is the vacuum at idle? Secondary rods/hanger?

If the float....FLOATS, it should be fine, no need to replace. Is this the hot air choke?
What is the base timing, and idle speed? engine mods worth noting?

oh, and finally, why do you think it's running lean? the plugs ?

86 sports coupe

The 305 is stock, The 800cfm will go on my 350 berlinetta. I read the plugs and they look brand new no fuel on them whatsoever.
The car wont idle, the base timing is at 4 degrees btc.The car will run with the choke half way closed with the engine warmed up.The turn is 4 turns out right now.

five7kid

iTrader: (14)

1-1/2 turns out is the normal starting point for non-cc carbs.

They also like more timing. 8 to 12 is more like it.

You are using a vacuum/mechanical advance distributor, right?

Sonix

iTrader: (1)

yea, I was just going to suggest more timing, in fact, that'll most likely help the most.

haha, you answered that funny, the 305 is stock, but not the engine that the carb is going onto, it's going on the 350... Can you guess my next question?? Is the 350 stock then? or a really lumpy cam for example?

What primary rods and jets are in the carb?

What is the idle speed you're going with?


I'd have to disagree with 57 on this one, (there's a first), I heard 2 turns out is a starting point with the non-cc, fair enough, but I think i'm at 3-4 on my bone stock 305... So I think you'll be a bit more....
after adressing the main points above, you could always drill out your idle mixture screw holes, but I think the timing and main rod/jet selection will probably solve it.

katman

You go five7!
Don't butcher your carb by drilling, fix the problem! There's a very good book on the Rochester Quadraget, get it read it several times, learn it, wear it out. It will be your friend.
What are the throttle shafts like? They can wear out and leak air and make it very hard to set the idle. Do the throttle blades all close completely when you back off the idle screw and hold it up to a light? Did someone drill holes in the primary throttle blades? This is common on big motors with small carbs.

Sonix

iTrader: (1)

haha, yea, that book is called rochester carburetors, by doug roe, sitting right beside me. Chapter 8 is about modifications such as drilling the throttle plates, drilling out the idle mixture screws, increasing your pump shot etc etc. It's not a bad thing, just do it right.

86 sports coupe

Here is the tube I blocked off. I think it needs blocked off when converting to an electric choke.The haynes manual says 3 turns out for bench setting. I have an non electronic qjet on it now that 2 yrs ago I took aprt and boiled on the stove and reused the old gaskets and it works fine.The car has the distribitor without vacume advance.I blocked off the tube between the main body and the choke housing and will instal tomorrow. I wanted to get the 800 cfm in working order for the 350 Im building. I dont know the main jet size. I wasnt planning on tuning it until I got it working. Later when I build my zz4 short block and run the LT-4 hot cam, I as planning on using a rpm qjet intake. Then I will jet as necisary. But for now I just want to get the carb to work.

Sonix

iTrader: (1)

I thought it does work, just badly, therefore needing tuning....

ok, your choice... boiled on the stove? in water? with...soap of some kind? After being disassembled??? Did it work to clean it very well? That piques my interest...

86 sports coupe

The carb that is on there was the one I boiled on the stove. The 800 cfm untit was dissassembled and soaked in the carb cleaner.
The 800 cfm is the one Im having trouble with.

Sonix

iTrader: (1)

ok, well you seem in limbo. If that carb is working for you, ok, give'r.... but if you want some help tuning/finding the problem on the 800cfm, feel free to ask.

86 sports coupe

I am asking for help on why my 800 cfm q-jet is running so lean. I can give you what ever info you ask.
Thanks Randy

Sonix

iTrader: (1)

ok, lets start a list then:

1) Do you have a vacuum gauge? Can you give us the reading at idle?
2) Can you find out the primary jetting/rods?
3) If the carb is on an engine currently, or can be put on one, bring the timing up to 10* advanced
4) What is the idle speed? (assuming there is a tach)

This is the main questions, with all 4 of these answered, I can help you out. (or hopefully someone else )

86 sports coupe

Give me a moment Im on to something. I pluged off that to that runs between the main body and choke housing. The car is idleing now but at a very high rpm, I thought i would try putting the rod in the 2nd hole, it doesnt work. Ive got the carb off now, so let me move the rod where it should go from here.

86 sports coupe

Thanks sonix for your help I will have more info in a sec.
Thanks Randy

86 sports coupe

I finaly got it to idle. I dont have a vacume gauge, I didnt have a magnifying glass so I couldnt read the jet sizes. Tomorrow I will set timing to 10 degrees and get back with you. The vacume leak came from here

86 sports coupe

Tomorrow I will be able to give you idle speed and what ever else you want right now it is late and I dont want to **** off the neibors. I have developed an exhaust leak. It always happens when I have a problem the exhaust wants to get loud and say" HEY EVERYONE HES WORKING ON THAT CAR AGAIN! HELLO,HELLO CAN YOU HEAR ME!)

86 sports coupe

Took it around the block, at 1st it wanted to idle at 1500 then it idled down to where it didnt want to run, then it idled up to 1500 and that is what it wants to do until you put it in gear. I tried 3 turns out now I have it 2 turns out. I pulled in the driveway left it in gear to shut it off and it didnt want to shut off. The screw where you set the idle speed doesnt even make contact. I think now its running rich, I will check the plugs tomorrow.