Engine will not idle...

[Ziptie]

Last raceday my engine would not idle at all. Would by idle on the grid and they stopped us on the track due to a wreck, and as soon as my car stopped, the engine shut off too.
It seems to be running fine under speed and only has the problem when I do not give it any gas or choke.

Now, when I give it throttle via the carb, I can hear air sucking in. I'm running the foam air filters and was told that might be the reason, but seems doubtful I should be hearing any air sucking in when giving it throttle no matter the air filter.

So... Any guesses?
I'm thinking one of the following:

idle to low (though it has always been find before and still doesnt explain the air noise)
carb needs cleaning (but it ran fine running full speed or even partial speed)
Vacuum leak

Any help is appreciated... Trying to race tomorrow. Haha

[VMS Motorsports]

Check your grounds, battery, and alternator output.
Which ignition system are you running?

[Ziptie]

You think the ignition system might not cause it to idle right but be fine running full power?  I'm running the black box setup with the ignition box running of a vacuum.
Thanks, I'm still new at this racing.

[VMS Motorsports]

If the battery  is questionable, the alternator will run the car at speed.
It sounds electrical to me, but try pulling the vacuum line from the booster and plugging it

[Ziptie]

Alright. The battery is new from a few months back, but Ill get a load test on it. It does start up after it shuts off nicely though.
Any idea on hearing the air sucking noise when giving it throttle?

Thanks again, I appreciate it.

[Bigmil]

It sounds like a vacuum leak.
Have you checked to make sure your vacum caps on the intake are all sealed properly?  Also I would take your carbs off and check the rubber boots that connect the carbs to the intake for any leaks.  I was told that they can crack with age and with overtightening (when a guy saw me overtighten mine    )

My engine never idled worth a darn until I got the carbs rebuilt.  Now it idles great!  I tried this but it didn't help me.  Take your air filters off.  Rev your engine up to 2k rpm and secquentially cover each carb intake with the palm of your hand.  They should suck pretty hard.  The engine should stumble pretty good when you do this.  I was told that this pulls an "extra" hard vaccum on the carb and may dislodge and debris that is pluggin stuff up.  If your engine stumbles more or less when you do this to one carb it may atleast help you narrow down where your problem is?

Hope this helps!

Gerad

[justfreaky]

Sounds like a vacuum leak to me. But, here's what my troubleshooting guide says:

a) Carbs incorrectly adjusted (too lean or too rich)
b) Fouled or improperly gapped plug(s)
c) Vacuum leak or leaking head gasket(s)
d) Ignition timing incorrect
e) Weak spark unit(s) or pulse generator
f ) Improper valve timing
g) Obstructed fuel line or fuel filter
h) Low engine compression
i ) Slow air cutoff valve faulty
j ) Choke stuck in open position
k) Incorrect pilot screw adjustment
l ) Clogged slow jet(s) in the carb(s)
m) Clogged air filter element
n) Improper valve clearance
o) Valve(s) and valve seat(s) require service

Steve

[VMS Motorsports]

Alright. The battery is new from a few months back, but Ill get a load test on it. It does start up after it shuts off nicely though.
Any idea on hearing the air sucking noise when giving it throttle?

Thanks again, I appreciate it.

I wouldnt worry about the noise, but then again I can't hear how loud it is.
Check battery...my first and strongest guess.
Check and clean grounds
Plug line off from Vacuum boost module.
No need to remove the carbs to check the intake boots, spray each one while running with WD-40, you'll hear the difference if theres a leaky boot.

Gerad, glad the carbs are working good for you