The Dodge Challenger Message Board

Dave you seem to be the resident expert on Carburetor issues. I have a 70 rtse with California emmissions. I got a replacement 4160 Holley with the fuel vent bowl to connect to the 3 way breather to complete the closed ECS system. From earlier threads I have said that my mechanic just cant seem to get the darn thing to idle right. At warm temps and higher speeds the carb acts better. All ECS vaccum lines are new, tank is new,etc etc. Any feeling this system could be bogging the carb down to cause uneven idling? Also, Herd mentions that the NOX system was used in '71 but my old windshield (build date 11/69) shows a NOX sticker. I do not see any of the solenoids or other hardware that was used. Strange? Do you know of this system that was used to retard spark advance? The shop manual mentions nothing!

I think this ECS system was considered a very simple NOX system?? Although it was just a simple vent pipe to stop fumes from the fuel bowl escaping into the atmosphere. I am not sure.

However there is no way I can think of that this could effect your car unless the vent was blocked. Then any evaporated fuel fumes could not escape and stop fuel getting in? Just a guess.

I don't think you actually answered my questions the last time you posted about this problem Steve. You thought at that time it was going lean. Well how do you know it is going lean and when exactly does it do it.

What is wrong with the idle? Simply saying it "is not right" tells me nothing.

What is the air/fuel ratio at idle. Are you having trouble getting that right at the same time as the idle speed?

Are you sure your timing curve is OK? No sticking timing weights or anything?

Do you have a non-standard cam fitted?

You might have to fit a oxygen sensor in the exhaust pipe to sort this out. You could always remove it once the carb is tuned perfect.

I'm no mechanic but mine has checked everything. We are going to remove the Holley ECS carb and try a Street Avenger with a little more CFM. If it bolts on and runs better then no issue. We'll see. Thx Dave

I am not sure how holleys work, but on my Thermoquad, the idle mix is changed by the main metering system. If you are lean, them perhaps a wider jet or thinner rod would help? Generally idle systems are not very tunable concerning mixture, the idle screws only affect amount of mix. I recommend getting the Holley carb book by SA. I have the Carter and it will help you figure out your carb function.

I had a similar problem with my TQ this winter, would idle but die when I put it in gear. Sometimes it would die if I took off the air cleaner, a sign it was lean. In my case I have a mild cam and running an old rebuilt carb. I got a set of marked drills and bored the idle jet a thousanth over and drilled the main jet to the HP motor spec which was three thou over. How does it run? Well it seems to run fine in gear now. Unfortunately I have yet to get the seats in to road test (redoing interior) and I just had Hernia surgery last week and I am not supposed to lift anything. It is finally 50's outside, I am frustrated!

I have read that to tell if lean or rich, remove a port to vaccuum, if idle lower or dies you are lean, if idle increases you are rich. Have yet to try it on a rich situation.

Tedd

Creating a vacuum leak can do the above but it can also cause the power valve to open, making the carb rich, which increases the rpm, which increases the vacuum, which closes the power valve, which makes the carb go lean, which drops the rpm, which drops the vacuum, which opens the power valve, etc, etc, round and round, causing the rpms to rise and fall in a cycle.

Steve has yet to say what the actual problem or symtoms are with his carb. If he could describe what the problem is or even start to answer some of the questions I have asked we could come up with a solution. Lets hope his new carb works first time.