Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

17058253 Post Build Drip

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Rte30tune:
I'm working on a freshly cleaned and rebuilt 17058253 carb from a 403 Olds. This is going on a chevy 350, with the following specs :

9.5:1
Vortec Heads, (Fresh valve job, and surfacing)
China dual plane intake
HEI Distributor
1 5/8" - 3" Headers
with an Elgin 1785-P Cam; (Similar to the Crane 278h?)
Straight Pattern Cam
.450 lift (I/E)
274 Duration Adv. (I/E)
218/218 @ .050
Lobe Ctr. 102/110 (I/E)
LCA 106

The first time putting the carb on and running as-is (after cleaning and re-gasketing..)resulted in nozzle drip and no response from the idle mixture screws.. fully seated and ran 11.0 on my AFR gauge.

I tried dropping the float to 1/2", to no avail.

I picked up Cliffs book and went thru the carb, bringing it up to recipe 2 specs, as this seemed like a good starting point. I also added an adjustable fuel pressure regulator, set to 5 psi. The float set back to the called for spec as well. Seat drilled to .130

Back on the engine, it started right up... (set at 10 deg. BTDC, idle at 800.. 28 deg. total timing in at 3000)

However, the boosters are dripping as before and the idle screws act exactly the same.. no change and they can be fully seated with no effect.  I even dialed back the fuel pressure to 4 to see if there was any change.. none.

Is my next move drilling the throttle blade holes? If so, how big? I also messed a bit with the AFR screw, but lost my notes on the initial factory setting.. what is the factory setting on that?

I'm out of ideas at this point..

Any suggestions welcome, Thanks!
Mike

77cruiser:
Don't drill the throttle plates. Open the idle air bypass, the idle tubes & down channels.
You can try adding timing first to see if you get much improvement.

Rte30tune:
Hey, thanks for the input. Looks like I’ll have to take it apart again.. how much would you suggest opening each of the mentioned orifices? I’ll try bumping the timing as well. I’ll be sure to take note of the throttle plates in relation to the idle transfer slots.

Thanks again,
Mike

77cruiser:
Try doing the timing first & see how it ends up. What's you idle manifold vacuum?

Cliff Ruggles:
Do not lower fuel pressure or lower the float.  Fuel pressure should be at least 6psi, I'd run 7-8 on that carb with the float at 9/32".

The problem is the camshaft.  Even though it's a relatively "small" cam the 106LSA degrades idle quality and requires more timing and more idle fuel.  It will be fine once you give it the idle fuel, idle bypass air and timing it needs.

No mention of jets and metering rods, gonna need some help there as well.  The CV secondary rods are fine.  I can spec out some better tuning parts, IFR's, and better rebuild parts for it.  If you kitted it with an over the counter kit the accl pump isn't going to make it anyhow......

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