Help ! The fumes are killin me..

[TC70C10]

I've read all the posts on tuning a q-jet on this site but right now I don't know where to go next.
A rebuilt 305 was installed 6 months ago
Original Q-jet that was rebuilt about 6 months ago. I can't seem to get rid of the "rich" smelling exhaust and smoke(black/blueish). I set the timing and idle and back out the screws to highest vacuum reading. I'm steady at about 17 in/Hg. I took air horn off last night and checked float setting. It actually appeared a little low (12 or 13/16)so I raised it to the 15/16 in(stock setting).

I also noticed when I put the vac line back on vac advance timing retards to about 12 or 13 BTC. This goes back to the question of whether the vac advance should have vacuum at idle.

I'm going to pull a compression test tonite.

Any ideas will be greatly appreciated

[PHOENIX]

vacuum advance should be on ported vacuum (vacuum only off idle)

[TC70C10]

Thanks Eddie.

Still haven't got to the A/C yet. I did take the compressor out of the box and one of the pulley bracket was busted. Shouldn't be a big deal because I'm all set up with the original aftermarket equipment.

[swervin ervin]

I have always hooked the distributor vacuum advance to a full manifold vacuum source. I know some will say they can't do this because they get pinging. May be true but it's just because they don't have the mechanical advance setup properly.

Vacuum advance is not for performance, only a better running engine at idle and gas mileage. Performance is gained from a properly setup distributor.

The stock float height of a Q-jet is somewhere between 13/32's and 15/32's. I'm hoping this is what you were meaning to say.

The rich exhaust means you don't have the carb adjusted correctly. To do it right, you need a tach meter and vacuum gauge hooked up. Adjust the idle mixture screws for highest vacuum and while doing so, keep the idle rpm adjusted to the proper setting.

If it's a stock Q-jet, or at least one with the APT feature, it's possible this setting could be out of wack. This will cause a extremely rich condition. The stock setting on this is right at 2 turns out from bottom.

Here's a pic of the APT screw location.

[TC70C10]

Thanks Mike

I've printed out all of the helpful info you and others have given me on this site over the last couple weeks trying to resolve this problem.

I'm back with the stock carb that I rebuilt 6 mos ago. Took the Caddy carb off last week. You might recall all of the vacuum line questions I had when I was trying to eliminate the can and TVS/EGR mess.

I reran all of the vacuum lines back to stock locations and ran the original carb 4 wheeling this past weekend. On the way back down on Sunday I started blowing smoke and smelling rich again.
I took this carb off when I got back from Tellico(Murphy,NC) because I couldn't fix mixture. I ran all the way back to AL with screws all the way in.

Since I reran the vac lines, I can make the engine stumble with my hand over the top of the carb(this is good). I just can't seem to get rid of the eye burning fumes.

I'll check into the APT if I can't get the mixture right tonight because that was not removed when it was cleaned/rebuilt.

My only question know is whether vac advance needs full vacuum.

I know you set timing with vac advance line plugged and running at idle speed so I don't know why you'd apply vacuum afterwards because that modifies the timing you just set..

[swervin ervin]

Yes, full vacuum. This is why you unhook the vacuum line when setting the timing, so it won't advance at idle.

BTW, I have some good articles on my site for Q-jets. Also for the distributor advance curves. Take a look at them in the Garage.

http://www.73-87.com/garage/garage.htm