Tunning issues

[Inline6Merc]

Hey fellas Ive been having some trouble tuning my car. The specs are 200 c.i, CI Aluminum head, 278 CI cam, 10 to 1 compression, DUI, and Holley 600cfm.
So the issue I've been having is that from a dead stop the car falls flat on its face and dies, also with cruising, when I put my foot hard into it, the car hesitates and stumbles and eventually picks up. In park if i step all the way down it just falls and dies.
I set the timing and adjusted the carb, with a vacuum gauge in gear and got a steady 15" of vacuum and 19" in park. So i have ruled out timing issues as it no longer pings and starts with ease.
It has come down to carburetor tuning. I have tried accelerator pump nozzles from size .37 to .18 and the smallest .18 has seem to work the best. Along with pump nozzles i have tried different pump cams and the orange cam seems to work the best but it just seems the car is getting to much fuel. Holley's smallest nozzle is .18 so im lost. I'm confident that too much fuel is the problem as it does not backfire and from the tailpipe a small puff of black smoke is visible. So where do i go from here? Thanks in advance!
-Curtis

 

[wsa111]

Curtis, replace the power valve. Install one with a 7.5" or even a 8.5" rating. The present power valve could be leaking fuel????

Set the float level to specs.

You need to get in touch with Doug-previously known as mustang geezer, now called inline fever.

He is running a 600 on his engine.

The dui should have 10 degrees centrifigul advance in by 2800 rpm X 2 = 20 + 16-18 initial = 36-38 total advance.

I would think an accerator pump nozzle in the 32-35 range should be close to your needs.

Replace the secondary diaphram spring with the lightest one, i think it is the yellow spring.

What is your fuel pressure???

With that camshaft the vacuum advance should be hooked up to manifold vacuum to enhance idle & part throttle acceration.

Let us know what you find, Bill

 

[Inline6Merc]

Vacuum advance is hooked up to manifold vacuum.

Fuel pressure is 6psi.

I'll change the secondary spring along with setting the floats again.

I'll go pick up a 7.5" power valve and try that.

Hopefully I'll report some good news tomorrow.

 

[62goldenrodvan]

Make sure you are on manifold vacuum.
Because ported vacuum will not have advance at an idle.
Google vacuum advance 101 and read it.
It fixed my problem once I under stood how it worked.
Kevin.

 

[fordconvert]

It helps if you think of it as a vacuum retard.

 

[Gene Fiore]

You're setup sounds killer...I've been thinking about that cam for my 250. How did you install the cam? Straight up or advanced a few degrees? Any luck tuning your Holley?

 

[wsa111]

Gene, wonder how this camshaft would work??

Use the 278 intake, but use the 292 exhaust @ 114 lobe center & advance the cam 2-4 degrees.

This is a solid lifter cam. I would use lifters that have a small .014 orifice in the center of the lifter for extra oiling. Also check for valve spring bind on the exhaust side cause with over .500" lift it needs to be checked.
This is figuring 1.6 rockers.

This would be a special grind but Mike could order it.

I hope inline6merc gets the carb or tuning issue fixed. Bill

 

[Inline6Merc]

So I'm still at a lose. I changed the power valve, secondary spring, set the floats, set fuel pressure to 5psi and still no change.

I messed with the jets and still seem to occur the same problem.

I wonder if the carburetor is just bad or perhaps the distributor is generating a weak spark.

Any help and thoughts are appreciated.

-curtis

 

[wsa111]

Curtis, if you have a spare 4412-500 2bbl carb, take the 50cc accerator pump & install it in place of the current 30cc pump. Then install the brown pump cam along with a .028 nozzle.

Is this a new carb you have or a used one???

If that doesen't fix the problem try another carb or distributor. Bill