Carb Flooded? Wet Plugs No start - Team Camaro Tech
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post #1 of 8 (permalink) Old Sep 13th, 12, 07:08 PM Thread Starter
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Mike
 
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Carb Flooded? Wet Plugs No start

Need some help here. I just swapped a Holley 750 vacuum for a 650 Ultra DP Mechanical on my 396 4speed and I'm having issues.

I installed per Holley's spec and its been running rich for sure. stumbling WOT from start and bogging at 1500rpms, 2000+ WOT seems okay, a few sputters at 3000rpm.

I know it needs to be tuned. THe problem is starting it after it's been running. I thought it was flooding the carb as it won't start up after its been running. I let it sit for an hour, still cant get it to fire. I pulled all 8 plugs, carbon mess. Plugs 3, 5 and 6 were wet. I cleaned em all up, and put em back.

Checked the fuel level for both bowls, on the Ultra DP, holley says keep fuel line at midpoint of fuel sight, did that.

BTW, running a crappy Holley Red Electric Fuel Pump w/o regulator. Was doing just fine before the carb swap.

I already checked to make sure I have gas, and pump is pumpin. Done.

I just need to get it running, so I can bring it to my guy.

Any ideas?
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post #2 of 8 (permalink) Old Sep 13th, 12, 07:33 PM
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Re: Carb Flooded? Wet Plugs No start

try bringing the float level down to where the fuel will dribble out only when you bump the fender with your hip. You will have to turn the pump on to do this.

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post #3 of 8 (permalink) Old Sep 13th, 12, 07:51 PM
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Re: Carb Flooded? Wet Plugs No start

A couple things will cause what you are experiencing... Too much fuel pressure or too high float adjustment. They cover it fairly quickly in the instruction sheet provided with the carb...

http://www.holley.com/data/Products/.../199R10321.pdf

This is the first Holley I've seen that they recomend the float adjustment to be half way up the site window. I'd lean toward the lower end of the site window and make sure you have between 5 and 7 psi fuel pressure.

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post #4 of 8 (permalink) Old Sep 13th, 12, 11:32 PM
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Re: Carb Flooded? Wet Plugs No start

And the 3rd thing... crap in the float level valve.

My Spelling is not incorrect...it is creative

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post #5 of 8 (permalink) Old Sep 14th, 12, 10:19 AM Thread Starter
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Re: Carb Flooded? Wet Plugs No start

I let it sit for the night and fired it right up this a.m.

In regards to the fuel level, on the ultra dp, it looks as if the fuel sight holes are lower on the carb than the other holley carb i have. That would explain why Holley is stating to set fuel level just below midpoint.

I suspect it's their junky pump flowing too much psi of course I couldn't find the right size allen wrench to pull the plug out of the fuel feed and put in my old pressure gauge.

According to Holley the red fuel pump doesn't need a regulator.

Anyhow, thanks for the help.
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post #6 of 8 (permalink) Old Sep 14th, 12, 10:22 AM Thread Starter
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Re: Carb Flooded? Wet Plugs No start

Yes Dennis, I lowered fuel level to 1/4 of the site window, however it didn't want to idle this a.m. But at least I got it started.

The carb is winning.



Quote:
Originally Posted by DjD View Post
A couple things will cause what you are experiencing... Too much fuel pressure or too high float adjustment. They cover it fairly quickly in the instruction sheet provided with the carb...

http://www.holley.com/data/Products/.../199R10321.pdf

This is the first Holley I've seen that they recomend the float adjustment to be half way up the site window. I'd lean toward the lower end of the site window and make sure you have between 5 and 7 psi fuel pressure.
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post #7 of 8 (permalink) Old Sep 14th, 12, 03:03 PM
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Re: Carb Flooded? Wet Plugs No start

Yes, as suggested earlier, one item to check is watch as the engine is running, fuel is not dribbling from the venturis, the cylindrical devices in the body just above the throttle plartes. If it is dribbling, float level too high.
Next, hook up a vacuum gauge to manifold vacuum port and tune/turn mixture screws for best idle, highest vacuum, alternate between the screws. May have to advance initial timing, say 8 to 12 BTDC.

The installed camshaft will determine the carb setting. More duration, less vacuum developed. Stock camshaft should acquire 18" to 20" of vacuum.

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post #8 of 8 (permalink) Old Sep 14th, 12, 03:17 PM
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Re: Carb Flooded? Wet Plugs No start

Quote:
Yes Dennis, I lowered fuel level to 1/4 of the site window, however it didn't want to idle this a.m.
Think about it...the level is lower, starts something is going right.....
But the suggestion above to lower till u can run the engine with the sight plugs out, but it give the side of the car a good bump a little will spill over (as Holley suggests) would be better.
Also if u have set the secondays and the idle / mixture screws with the float level too high they will now be wrong....
Also reset the secondary butterflys so the mixture and idle speed screws are withing 1/2 turn of 1 1/2 turns of factory setting with about 16 to 18 degs idle timing.
Then At WoT set the gap in the accelerator pump to between 15 and 18 thou... not a critical gap, just so long as about that gap...
The carb is good to go...
From there the timing can be dialed in.

My Spelling is not incorrect...it is creative

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