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vacuum leak

K

klb76

Guest
I am checking for vacuum leaks with spray ether around carb and manifold (it should speed engine up if it sucks ether into engine) I found nothing but then I sprayed the ether into the air cleaner and it almost killed the engine instead of speeding it up... to my knowledge it should speed engine up the engine here too.. maybe my carb is getting too much fuel already?? Would this explain my phantom idle speed changing on its own after running for awhile?
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
It could.

Here is an idea for you. I don't smoke, but finding somebody that does is aweful easy.

You get a smoker to puff a cig for you, then go to the main vacuum source lines on the intake and have them puff a lung full of smoke into the line. Now, you sit back, watch and wait. Look under the dash at the headlight vacuum switch/valving, the headlight actuators, emissions canisters, cruise control, power brake booster, etc.

If you see smoke escaping anywhere, there is your vacuum leak.

As far as the engine goes, you may simply have significant wear in the throttle plates on the carb. That means that the throttle blades actually move and wiggle around changing the adjusments and making your idle move up and down.

Straight Ether in a running engine won't always make it race up, especially if you are already rich.

Good luck.
 
R

rpounds

Guest
Be very careful squirting Ether around on a running engine. It could be vary hazardous to your health . . . at least hazardous to your hair!!

Luck . . .
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
So when you have this "Phantom Idle"

....Ohhhhhhh I like that phrase.....

Look OUT...it's PHANTOM IDLE MAN!

( snap outta it VIG!....)


So does the idle go UP or Down when the Phantom Idle.


Vig!
 
K

klb76

Guest
It has only happened twice in the past two months... after about 4 hours of driving both times, whenever it was in nuetral or the clutch was pressed the idle would sky rocket... not to the point it was uncomfortable but definitly higher then normal... I am having a problem with the choke too, it is broke/being worked on so for now it is just held open all the time... if that helps?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
What happens when you blip the throttle

No effect?

I would go on the VAC leak hunt.

More AIR will increase the idle.


Vig!
 
K

klb76

Guest
it hasn't happened in awhile... but I think when I blip the throttle it usually seems to reset the idle... but not always... like i said it has been a couple of weeks, only on long trips
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
You could have a weak pull back spring

The factory GM spring for the pull back of the carb butterflys ( in MY opinion ) was WEAK.


Check it out.....

with the car off... open the throttle by hand
and SLOWLY let it back down... does it stop?

Now can you push on it just a bit more and she will really stop down?

Vig!
 

barrier5

Well-known member
Joined
Dec 27, 2001
Messages
126
Location
janesville wi usa
Corvette
1982 bright blue coupe
It could be the high idle cam is rocking up at times, since there is to tension on it with the choke wired open.
 

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