Hey all! What the heck is this thing: I have a SBC Edelbrock tri-power manifold, the center carb is a Bay City version and it has this thing on it. I can't figure out what it is and what it does! (Note, pic isn't of my carb...borrowed from @Erik B 's classified thread.) Thanks guys!! -Mike
its called an Idle air compensator.. my understanding is in extremely hot engine operation it allows more air in at idle to offset excessive fuel vapors caused by percolation. helps maintain a smooth idle. under the cover is a bi-metal strip that is temperature sensitive. opens a small valve to allow more air into venture. Hope this helps. Clete
@Clete yes, that makes sense. So some 2G's have this and some don't...my end carbs don't have this...is this a desireable thing? Should I defeat it? Should I look for another carb that doesn't have it? Is it nothing to worry about? Did they perform as desired? -Mike Sent from my iPhone using The H.A.M.B. mobile app
Not sure you would need them on the outside carbs on a try power....the outside carbs should be closed till needed.
Clete is correct. Another name was "hot idle compensator". This item was added to address stalling at stop signs/signal lights by vehicles with automatic transmissions when the ambient was above roughly 85 degrees F. (30 degrees C.). In general, hot idle compensation was used mostly on vehicles with automatic transmissions. As far as factory tripower setups were concerned, only the center carb ever used HIC. Jon.
@Clete, @saltflats, @carbking, thanks so much Gents. Now that I know what it's called I've been able to find a ton of info. I'm pretty good with the googles but I didn't know even what I was looking for!! Based on what I've read I'll make sure it remains present and functional. It'll be good to have even if I never need it to come on.... -Mike
I have found this to be very interesting. I never knew any such thing existed. I checked the six 2GC's that I've accumulated and found that one of them has this. So let me recap: 1. if I use this in a tri power setup only the center carb needs to be this one, 2. if I happen to use this setup on a 4-speed car none of them need to be this type. Is this summary correct? Next: if (1) this one happens to be one of the best three that I have and (2) I use this on a manual trans 3 deuce car can/should this part be removed or disabled? OR should it just be left alone?
Mike - In addition to the location pictured by the OP, many of the HIC were inside the carburetor, located between the two venturii. If present, it will be seen by opening the choke butterfly, and looking inside the carburetor. There are hundreds of variations of the Rochester 2G series carburetors. As to your two questions, there are no absolute answers. My previous post listed the general application by the car manufacturers. But generally, there is at least one exception somewhere along the line. However, I did NOT use HIC on the two AFB's on my shop truck with the 390/4 speed; and I am located about 45 crow miles from you, if this helps. My dual quads are linked for simultaneous operation with both idle and choke on both. Jon.
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