The mod shown in the pic below I have done countless times over the years & in EVERY case it provided a veeeerry noticeable increase in performance.
The bullet ends of the discharge tubes [ DT ] are cut off just where the bullet shape ends. I got this idea from the comp Series TQs. I use a Dremel with a 1" cut off wheel to do this.
Next, you need to solder closed ALL the small holes in the DT. Use emery to clean the surface. Then use an electric sol iron [ about 80 watt ] & resin cored solder. Do NOT use a gas flame, it will oxidise the brass & the solder will not bond. After soldering, run a drill up the DS to clean out any solder that may have got in.
I always remove the choke linkage; doing this exposes a small T shaped hole in the air valve [ AV ]. I braze a small piece of steel over this hole because in the original configuration that hole was blocked by the choke linkage. I have not tried this without blocking that hole. If you do not have access to brazing/welding gear, you can pop rivet a small plate over the hole.
- Set AV spring to 1.5 turns.
- Start with 137-143 sec jets. Drill out smaller jets.
- Sec high speed air bleed. You can see it in the pic, the long brass tube that sits inside the fuel jet. I have only found 3 sizes that Carter used, but we have limited numbers of TQs in this country, so there may be others. I have found 027, 029 & 039-040 air bleed sizes. You want 039-040. If smaller, drill them out. You drill the pinched section of the tube where it protrudes into the air horn. Use a 039-040 drill. It is better to do this in two stages, as removing 010 in one step may break the drill bit. Use a 033-035 drill first & then finish with the 039 bit.
Adjust the WOT position of the AV for a dimension of 0.800-0.850" from the dimple to the black body. This can be varied if needed or experimenting.
One final tip. With the AV dashpot held in with vacuum, you want about 0.100" of free play between AV & the AV stop on the airhorn.
The front portion of the AV has a bend in it; the AV on the Comp Series does not have this, it is straight. have not tries bending it straight to see the effect.
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