Interesting information from Stovebolt re: Timing. True?

If I open up the secondaries too much, then fuel will leak of that ventri. So, agian, there is a 'sweet' spot where I can crack the secondaries up JUST A HAIR, and I have no more fuel leaking.

Click to expand...

I don’t know if I agree with Tom. With the progressive carbs 5200, DGV and DFV there is only one idle circuit or one idle screw. There should be no need to have the secondary plate open at all. I can think of a reason to do so however. Like if you have a condition that is causing you to open the primary plate beyond the correct setting in order to get enough RPM for idle. So I don’t know how far you can play with the secondary throttle plate opening to add any needed “Extra Flow” before you activate the progression holes in the side of the secondary venturi. I would be careful; you may end up a rich condition from the activation of this secondary progression circuit.

As an example of what I’m trying to say would be a problem I had created after adding the larger "jugs" to the VW and kept the single port heads. The larger pistons increased the CFM for the same rpm at idle. The point being, the throttle plate had to be opened a bit more than it was designed too, to allow for the increased need for flow at the needed rpm. What happens is, the edge of the throttle plate is now out of the proper setting to activate the idle circuit. You end up “idling” from the main jets rather than the idle circuit. In my case with the single venturi Solex I had to drill holes into the throttle plate to allow additional flow without changing the proper position of the throttle plate.

With the progressives you could open the secondary to make the need adjustment as long as you don’t start drawing in fuel at idle.

I hope I haven’t muddied the waters too bad. Good luck and have a great holiday, Ric.

I still say the secondaries don't need to be open, even with your combo. If it's pouring fuel with the secondaries closed, you've got a float setting or jetting problem. The Webers are easily (although not cheaply) rejetted.

Where is the fuel coming from?

I think a good portion of your problems lie in the carburetor being out of whack. Without a consistent signal to the idle circuit, you'll be fighting your idle and cruise tuning forever. Get and set a baseline setting to work with, then tune from there; I have yet to see someone drop on a Weber and go without a little tuning.

Regarding the "under load" timing issue- I was just trying to point out that a rev in park is okay to check total #s, but they won't reflect what the under load combination of vac and mech advance will be. This is why you're hearing many different #s from others.

JEFF

Does your carb look like this?

I can think of a reason to do so however. Like if you have a condition that is causing you to open the primary plate beyond the correct setting in order to get enough RPM for idle. So I don’t know how far you can play with the secondary throttle plate opening to add any needed “Extra Flow” before you activate the progression holes in the side of the secondary venturi. I would be careful; you may end up a rich condition from the activation of this secondary progression circuit.

Click to expand...

This is exactly the situation that Tom described. I was having to turn the idle speed screw down quite a bit to set idle (also keep in mind that I was running a much higher idle than I thought I was - like around 1100 in park) - so yes by doing this it allowed me to reduce the turns. Also now I have the idle set at a true 900-950 in Park.

OhChicken - No, mine looks a little bit different from this. It's very similar, and I thought it was the same at first glance, but the layout of mine is different. For example, my fuel inlent faces my choke -- this one is on the other side of the carb. If you go to this picture http://home.centurytel.net/fordfan/Falcon/Images/stvfrd5200.jpg mine looks very similar except with an electric choke.

If I close the secondary all the way, fuel starts to "spray" out of the center of the venturi, which causes my idle to be uneven. With it open just a hair, both carb centers are dry.

So, do you guys think I'm running to lean? I have 233 primary and 255 secondary jets. Should I go higher?

Hello CC:

I've been reading some of your posts regarding the timing/carb problems with your engine. What's odd is that I'm experiencing very similar problems with my new motor. Right from the start I've struggled with getting the engine to run properly. First the engine was idling rough. After hours of tweaking the 5200 it is running better at idle. The solution to the rough idle was to adjust the secondary butterfly because at idle it was dumping fuel out the venturi.

My timing has always been way advanced (30+). I checked everything and still can't figure it out. It is really driving me nuts. Unforntunately, I'm in the middle of a full disc brake and rearend swap and cannot run the car to give you the exact numbers. I should have it back together in a few weeks and will have at it again.

I know I haven't helped you at all with your problem, but I wanted to let you know that you're not alone with your problem(s). Keep posting your status. I sure want to know how you progress.

Falcon63

1963 Falcon Convertible
200 CID, 252 comp cam, HSC pistons, Duraspark, ported head, Holley 5200.

Thanks man! Good to see I'm not the only one!

Interesting that you and I have the same cam...

Bascially, everyone I've talked to has basically said -- this isn't really possible. That I can't be running this much advance unless something is really wrong.

Well, today I went to a place that specializes in carb rebuilds and distributor recurving and timing. I talked with them about the car and timing they were surprised. I asked them to take it for a drive and see if they could hear ping or detonation. They drove it around and said it seems to be fine.

Saturday morning I have an appointment for a tune, etc. They are going to look over the whole system and try and figure out what is happening. They're going to check the dizzy, plugs, carb, etc. and see what we can figure out.

I *hope* to have more info on Sat and will certainly post any results!

"The solution to the rough idle was to adjust the secondary butterfly because at idle it was dumping fuel out the venturi. "

This is exactly what I was trying to describe. The volume of air through the intake at idle is greater than the primary throttle bore can handle without activating the Main Jet Curcuit. By opening the secondary throttle plate the excess flow (cfm) allows the primary throttle plate to return to a position that operates the idle curcuit.

”Also now I have the idle set at a true 900-950 in Park.”

Having the idle set at such a high rpm I think is part of the problem. Is there a reason you are setting the rpm above 600?

Is that HIGH? Wow!

I have to run it that high in park, so that when I put it in drive I can get it down to 650 - 700 rpm. Anything less than that and my car won't idle.

650RPM in gear seems to be about what the book calls for, I thought.

Point taken about the carb. I think I may be too lean. I'm going to order some jets from Stovebolt and see if that changes the problem.

I think that's the problem- your jets are out of range. Your idle air bleeds are probably too small.

Have you checked out any carb-tuning sites?