Solved 2 Charger problems this weekend - a Tranny problem and and Idle problem!

[Corellian Corvette]

Nothing feels better then solving some nagging issues! 

The 68's been done for a couple months, but as everyone knows you end up chasing down small little things as you drive it and work out the kinks.

The two that have been bothering me for a while, that I finally fixed:

1. The cam is a bit too aggressive for my auto transmission, and I could never get it to idle properly at low RPM in drive. It wouldn't die, but it would shake and rump pretty furiously. If I cranked the idle speed up, it would diesel when I shut it down. 
2. The 727 wouldn't downshift. There is so much torque in the engine it wasn't a big deal, but if I stomped on the throttle I could never get it to kick down from any gear.

Well, both problems got solved this weekend and I thought I'd pass on the solutions.

1. Solved the idle speed by taking a page out of a Corvette setup - the problem was that the Charger idles GREAT right around 900 RPM. But you'd put it in "D" and it would lug down to 650-ish and shake pretty good. If I jacked up the idle screw, to get it to 900 in D, it would be at about 1200 in P and it would diesel and sputter on shutdown. Solution was to get an idle compensator solenoid http://www.jegs.com/images/photos/300/350/350-8059.jpg. On my '73 Vette (which does *not* have AC) the idle compensator is used to actually adjust the idle speed - not the idle speed screw - for this exact reason. You set the idle screw to something that just keeps the car running - say 500 - 600 RPM so the throttle plates don't completely close, and you can get the idle where you want it using the soleniod. When you shut the ignition off, the plates snap shut and you don't diesel. So, now I have a nice smooth idle at 900 in D, 1200 in P, and no dieseling!

2. Downshift problem was solved accidentally! I had always adjusted the shift linkage EXACTLY to the assembly manual – put a drill bit through the hole in the linkage, adjust the rod going down to the tranny so the lever is pulled forward, then adjust the rod to the carb. (I'm truncating the instructions). I did that as a baseline, and it was my understanding you could adjust line pressure by lengthening the rod to the carburetor ever so slightly – so long as at WOT you still had a little adjustment yet at the end and weren't maxing out the line pressure.

Well, when I was under the car tightening some suspension parts, I took a look at the linkage from the underside. I noticed when I popped of the lower rod (that comes straight off the transmission arm) I actually had 1 to 1.5 inches of forward movement!! That means even at idle, the linkage was pushed back 1.5 inches! Well that seemed like a problem, so instead of adjusting the linkage from the top, I did it from the bottom – I put the drill bit in the hole, got underneath the car, held the lever forward, spun the rod up from the bottom and connected it when I was sure the lever was ALL the way forward.

I re-adjusted the rod to the carburetor and WOW!!! What a difference that made! Shift points were still good, but the car will now downshift at all gears. It's amazing the difference it makes! If the car is lugging even *slightly* in 2nd gear, I hit the throttle and BAM it shifts down.

I've seen a lot of recommendations here to lengthen the rod if you're having downshift problems – but if that's not working for you, get under the car and make sure your linkage is ALL the way forward and baseline from there!

[Nacho-RT74]

1. Solved the idle speed by taking a page out of a Corvette setup - the problem was that the Charger idles GREAT right around 900 RPM. But you'd put it in "D" and it would lug down to 650-ish and shake pretty good. If I jacked up the idle screw, to get it to 900 in D, it would be at about 1200 in P and it would diesel and sputter on shutdown. Solution was to get an idle compensator solenoid http://www.jegs.com/images/photos/300/350/350-8059.jpg. On my '73 Vette (which does *not* have AC) the idle compensator is used to actually adjust the idle speed - not the idle speed screw - for this exact reason. You set the idle screw to something that just keeps the car running - say 500 - 600 RPM so the throttle plates don't completely close, and you can get the idle where you want it using the soleniod. When you shut the ignition off, the plates snap shut and you don't diesel. So, now I have a nice smooth idle at 900 in D, 1200 in P, and no dieseling!

great you figured out!!!

( BTW 74 Chargers got the iddle solenoid )