What Causes a High RPM Holley Cough?

[dcdoug]

Did you have to throw it across the room to get it dialed in properly?

[elmariachi]

Originally Posted by dcdoug

Did you have to throw it across the room to get it dialed in properly?

Hahaha, no, but I did do one of those tequila-induced voodoo exorcisms on it. Here is the deal with this carb, for those who care:

1. Setting the float levels with the cathedral bowels is a pain in the butt because it involves removing the bowels, then the floats themselves and bending the tabs. Real scientific there Mr. Holley. The way the engine sits in the car and the slant of the intake means you might have to deviate from normal float settings. LOTS of trial and error.

2. The horizontal needle and seat design is an invitation for trouble because gravity ain't on your side. Somehow my front one stuck open on the UPS ride back from Keith and it flooded the intake and a couple of cylinders with lots of raw fuel. That was a real mess.

3. My Mighty Demon 750 uses 72P and 77S jets. To get this one right I am at 77P and 85S, a lot more jetting than I would have expected with a Sidewinder intake and stock MR heads. Ironically, I think those are the same size jets that came from Shelby.

4. I had to take all the play out of the pump arm and upgrade to a 31 discharge nozzle to get a healthy pump shot. I am using the pink cam in the #2 position.

5. PV is 4.5, I am using the lightest vacuum spring in the Holley kit, and I am a fat 1.75 turns out on the idle mixture screws.

Timing is set at 18* base, it idles nicely at 900-950 rpms and runs good. Other than the cough I'd say its sorted out and behaves predictably. Looks cool, but doesn't run quite as stong as with the Demon double pumper though. I am still moving on to the 2x4s.