If you listen to the video, you can hear a popping sound (sounds high pitched on the recording, but believe me, it sounds like backfire) on the driver's side header. One of the valves?

I double checked the timing a couple of times just to be sure, and played with a little retarding (knowing I am going to mount the blower eventually). I left it at 10 degrees advance, but could not get it to "idle" either, even though the throttle set screw was backed all the way out, and I double checked the secondaries were not even remotely open. The idle set screws would not respond, but then again, this engine was way above idle, and I am sure that the idle circuits were being bypassed.

This did not happen with the 2 barrel I had previously, nothing changed until I added the teapot (which I modified the jets, passageways, etc)...any of you blower boys have any ideas here?

http://s249.photobucket.com/albums/gg208/danaxjessup/?action=view&current=100_3985.mp4

Click the above link to see the video...

I hear the "Pop" too but with open headers on decell it seems only natural.

Maybe the headers are now the difference in what I hear, but it is definitely only the drivers side that has anything remotely abnormal.

Basically, I believe that I ruled out anything that has to do with the ignition (cap, points, rotor, wires, etc), but isn't the popping backfire a problem when a cylinder sees a spark at the wrong time? or maybe residual spark somehow?

Still do not know why the idle will not come down. The only thing that I can think of is that I installed the butterflies on the throttle shaftbackwards??? I will have to pull the carb next because once the idle set screw is backed all the way off, the choke fast idle cam is backed off, etc, this thing will not respond with an idle change at all. It acts like part throttle is open. It is getting air from somewhere right? You can see the secondary butterflies as the engine runs with the blower carb hat off, and they are definitely closed.

Another item. I did check the vacuum at idle when I had the two barrel on the engine (at idle it was steady at 18 in).

One thing I will say...this engine seems to be very responsive to throttle changes with only the mechanical advance (I plugged the vacuum advance port on the carb plugged)

thanks for all these ideas

Sounds great! Come on out to the east coast - I'll put you up!

On the throttle lever side of the carb, the secondary throttle arm has a slot, and a wire link connected to the primary arm slides in this slot.  If the link is too long, it will bottom out in the top of the slot and prevent the primary throttle from closing all the way.  Bend the link until there is a little slack.

Too late to fire it off tonight,,, my 7 year old son wouldn't mind waking up to the Y block, but momma and the girls might have a few issues...

I should have some time to fire it up again tomorrow afternoon.

It takes a while for the carb to respond to the idle mixture screws - I believe because the idle is so high, it is almost irrelevant to even adjust them, but I did get responses from lean to rich that showed up in the way the engine ran and in the smell of the exhaust.

After chasing it for a while, I gave up and had supper with the family and installed several outlets and ran a bunch of wire in the garage - at least that went according to plan!

 Remove the vacuum hookup to the distributor and see if the surge dissappears. It's possible that you are seeing the distributor advance and retard as the manifold vacuum changes.

I never did hook up the vacuum advance...I used a threaded plug to block off that port on the carb itself.

The more I tinker on this thing, the more I believe that I need to go through that carb with a microscope. Something is causing that thing to get more air/fuel mix (when I have the butterflies closed) than is common...otherwise I would be able to get that idle down where it needs to be. Really don't want to change carbs, I am sure something off the shelf would be much easier, but where is the fun in that? Why not take hours chasing down problems that you only created for yourself???

On another note, check this link...will this vacuum regulated fuel bowl help the situation for giving me more fuel pressure when I need it? I am going with a Hi Volume FE fuel pump with a Mr Gasket electric pump to help the pressure when we go into high boost...

ebay #: 370399635679

One item I do have is a small carb leak where the accelerator pump shaft is located. Nothing at idle, but when I blip the throttle I can see a little bit of seepage of gasoline...YIKES! I guess I need to revisit the paxton manual and find out what else I may have done "wrong" on the modifications. I thought I had that shaft sealed up. Looks like an o-ring might be the next logical step to get that right.

Now, I have yet to modify the fuel pump, and/or make any fuel pressure upgrades, so I am obviously a little bit leary about running the motor at anything more than an idle - she will just run out of fuel in the bowl. I do have a brand new FE hi flow mechanical pump that flows up to 9 psi - that should be good, just a little concerned about over powering the teapot float/needle system in the bowl.

I have not modified the distributor yet because I have no vacuum advance hooked up, so its all mechanical advance from here on out.

Promise to get video of the blower setup up on the internet very soon!!!   

Way Cool! Especially since my dad was in town this weekend and got to see the whole works!

You need to "boost reference" your throttle shafts to stop the leak since the boost is trying to force it's way out any way it can. I built a dual paxton set up for a 427 Ford many years ago a had to deal with all of the same issues. Anyway for the throttle shafts I found ,perhaps through Paxton I can't recall, aluminum spacers to go between the carb and Intake. They looked like a spacer used to hook up a pcv valve. Difference was they had a hose nipple in the back and 4 holes drilled under the throttle shafts, right between the throttle plates and the outboard shaft exits. By drilling corresponding holes in the carb base plates and connecting a boost line to the hose nipple you equlize the pressure in the throttle shafts and prevent the leak. If you wanted to run a more modern Holley carb you would do one additional mod where you would "boost refference" the float bowls by putting a screw in fitting (hose nipple) into the top of the bowl and connecting that to boost as well. This way the pressure is equalized in the float bowls . Otherwise the boost will try to blow the fuel back into the bowl and not down the venturi's. As for the fuel pump I ran an electric along with a "boost refferenced" mechanical pump. The trick is to modify a Holley fuel pressure regulator and "boost refference" that as well. That way as your boost increases so does your fuel pressure. If you call Paxton you may be able to buy the spacer plate and the modified fuel pressure regulator from them. If that doesn't work let me know and I can give you another source.

Pete

Pete, He's running a teapot. Different bag of snakes from your experience!

If I remember, that shaft is hollow on that pump rod - time to break out some good ol' JB or epoxy.

Fellas, check out my other posts in the This and That section to see updated photos of the entire setup. I did get the air cleaner mounted with the portable engine-run stand tonight. I really like the looks of this thing! Wait until I clean it up and paint