2 replies to this topic

[150DollarRacer]

I pulled off the air fliter assembly from the civic this past weekend to clean out the carb a bit. I washed it in carb cleaner and then while it was running i dripped some MMO down each barrel to try to get it nice and clean. The good news is that the car used to "idle" around 1500rpm and now idles around 800 or so. Its still very erratic like there is a vacuum leak or a bad spark plug, but its doin better.

Anyway, I noticed that only one of the barrels is connected directly to the throttle cable. How does the second one actuate? Is it mechanical or vacuum modulated? If its mechanical then I think the linkage is broken because trying to rev the engine while under the hood, I didnt see the second throttle plate budge one bit.

Is this a common issue or is everything working right?

[Davidov]

Yes, it is vacuum activated.
It's hard to get the secondary to open by just free revving the car, since it works better when the engine is under load.

If you think they aren't opening (if you are lacking top end power) get a hand vacuum pump and see if the arm opens.

Be careful revving the engine with your face over the carb....I've seen some pretty nasty backfires come out of the carb.

[150DollarRacer]

Where is that particular vacuum line located?