"Surging" in gear with brakes on at stoplight...

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Mojoe9955

Mojoe9955

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Car idles, runs and shifts great but in drive at spotlights and signs it "surges"..not bad, and with my foot off the brake it creeps ever so slightly, not like it wants to takeoff and it idles fine when I shift into neutral, but enough that you need to keep decent pressure on the brake to hold it back.
The transmission was recently rebuilt and it took quite a bit of tinkering to get the shiftdown linkage just right... maybe not?
 
Power brakes? If so, pinch the vacuum hose shut going to the booster and see if that stops it.
 
Sounds like the booster has an air leak. Above test will prove it.
 
Both of the above are probably right, but timing can have a significant effect too.
Put a timing light on it, in gear. Does the timing move around at idle in gear?
If so, figure out why. Advance springs, vacuum advance, whatever the issue may be. Idle timing shouldn't fluctuate much while in gear.
Obviously block the tires or use a helper or ensure the parking brake works really good if you're going to check anything in gear..
 
No power brakes. The ammeter fluctuates when this is going on, so it could be the timing. I'll pinch the the distributor vacuum line and see if that makes a difference...
 
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Yes, I had my converter rebuilt, and if "trans creep" is a thing that could be it.
 
I'm pretty much stuck with what I have now. I'm not sure if it's "hurting" anything, it's just annoying.
 
With no power brakes, try pinching the PCV hose shut. It may be the PCV valve is bad or the hose has a leak.
 
Mojoe9955 said:
Yes, I had my converter rebuilt, and if "trans creep" is a thing that could be it.
Click to expand...
Normally when one creeps it's because of factors other than converter causing too high an idle.
 
The transmission is still under warranty, so I'll take it over there and see what he can come up with.
Thanks
 
I'll toss my opinion in with those that point to a carb issue; whether it be the vacuum signal to the carb, or a powervalve issue, or a problem in the synchronizing of the fuel coming from the Transfer Slots versus from the Idle discharge ports, or the IABS/emulsion tubes, or even the wet fuel-level.
But above all, the timing better be stable
 
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