help carb or vacuum issue maybe.

[cudasteve72]

So I'm not totally sure but as I'm driving and let off the gas and push in the clutch the rpms go up to around 3000.  It kind of starts to go down when I hit the brakes (power) but not to where it should idle.  I have a proform 850 mechanical secondary carb that only has one manifold vacuum port for brakes and pcv, nothing on intake all seem to be connected or plugged.  Any ideas

[734406pk]

How does your engine idle in park/neutral? Do you have the correct throttle return spring?

[Chryco Psycho]

Lots of ideas  , wish I was there !
 any binding in throttle cable , linkage or kick down linkage , strong enough springs for both kicck down & throttle , carb snaps closed when it is opened ?
 dist advance weight springs OK & advance plate moves freely , vacumm advance disconnected ?

[cudasteve72]

I have a rev n nator, they recommend not running the vacuum advance.  The throttle does snap closed.  Just sitting in neutral in the garage it idels fine, maybe a little rich but smooth and normal. The only issue with the cable may be the travel distance but it is smooth too.

[734406pk]

A frayed throttle cable can easily cause your issue. I would recommend changing this cable asap as it can be dangerous to drive this vehicle if the cable is sticking. If the problem persists we can move on from there.

[YellowThumper]

X2 on changing your throttle cable if it is even frayed a little.
Learned by error on mine. Had car up to about 115 with throttle wide open before I just had to turn key off.

[734406pk]

The only issue with the cable may be the travel distance but it is smooth too.

What is the issue with travel? Does the cable allow the throttle plates to return to the idle stop?

[cudasteve72]

Im not. Sure if it goes wide open it closes good though.

[734406pk]

If you rev the engine from idle to say 3000 rpm, and you let off the gas peddle, does the engine return to its idle rpm consistently? Or do you find it hanging up?