My question wasn't directed at anyone person but all those knowledgeable in the art and science of Quadrajets. Any help is greatly appreciated

When I was removing the Air Horn from my Quadrajet it was missing one of the Secondary Emulsion Tubes (Air bleed). I found it in one of the holes in the main fuel bowl. I pressed it back into the top of the Air Horn, but after doing so, noticed that the tube passes up through the Air Horn. It seems to me that this is too far and no longer exposes the end of the tube to the secondary fuel discharge nozzle below the air doors. Is this correct? The other side that didn’t fall out appears too high also. When trying to position then in the Air Horn so as to expose the end to the secondary fuel discharge nozzle the Air Bleed tubes fall out. Should I press the Air Bleed tubes into the Air Horn and once I have it installed on the main fuel bowl, push the exposed end of the Air Bleed Tube down through the Air Horn?

Thanks

pat

 

This sounds like a question custom made for......... Lars!

-W

 

When I see questions posted about Q-jets, I actually look forward to see what Lars has to say

 

The air bleed tubes should be a press-fit into the holes in the air horn. If they are no longer tight in those holes, correction needs to be made so that they can be inserted to the proper depth and so that they will not vibrate loose/drop out again. The simplest fix would be to put a bit of Loctite on the end of the tube before inserting it in the air horn hole. You need to clean the hole and the end of the tube well before putting them together. Fine sandpaper (600 grit or smaller) for tube and hole, then lacquer thinner or other cleaner, dry, then Loctite them together in correct position.

If you think that will not hold the part well enough, you can expand the end of the tube a bit by inserting the tapered end of an ice pick (or other similar item) and driving it/twisting it in a bit to enlarge the tube. Since the smaller diameter at the lower end of the tube is the important feature on that tube, a little bit larger at the top will not matter at all.

To find out what Lars would recommend, send him an e-mail at V8fastcars@msn.com .

 

Pat -
There are 4 tubes pressed into the airhorn: Small-diameter inner tubes which are air bleeds, and large-diameter outer tubes, which are fuel feed tubes to the secondary fuel discharge ports located above the airvalves. There are no tubes feeding fuel to the large discharge tubes/nozzles located below the airvalves. The inboard, small diameter tubes intersect the large discharge tubes, but protrude up through the airhorn casting, and are exposed to atmosphere. The outboard tubes press into the casting until they bottom out on a ridge, and these feed fuel to the two small discharge holes located just above the airvalve. If they get pressed in too far - beyond the stop feature of the ridge, they can block off the discharge holes, but I've never seen this happen.

The two inner tubes go all the way through the airhorn casting, and protrude up above the casting slightly. The photos below show the brass tubes protruding through the casting at the minimum level. Most tubes will stick up above the casting about 1/16”, exposing most of the necked-down portion of the tube end. You can put some LocTite on the tubes to keep them in place. You can also see the small fuel discharge ports just above the airvalves – these are fed by the larger, other tubes. The main discharge tubes protruding below the airvalves are fed by the large internal passage coming up through the float bowl from the secondary metering orifice/rods.





Lars

 

Thanks for the information and the recommendation that I seek out Lars's advice. I emailed him and as you can see from his post he straightened me out. Had I not, I would have inserted the tubes to an incorrect detph.

Thanks everyone for the help and advise, and a big thanks to Lars for being a resource of knowledge for us Quadajet users.

Pat