I have a 200-4R behind my JW 470 in a 1985 Regal with an under dash switch to engage the lock up converter. The trans shifts great and in overdrive I'm turning 1700 rpm at 65 mph with my 3.50 gearing and 27.5" diameter Hoosier Quick time tires. The lock up switch works good I can feel the converter lock up when I switch it on but I notice a slight jerking feeling to the car when its running in lock up. If I turn the switch off the jerking feeling goes away and it runs smooth down the road. Is this something anyone else has noticed or should it be expected ? If its abnormal any ideas about its cause and what is the difference in running the converter locked up at highway speeds as compared to running it unlocked. I haven't been locking it up till after its in 4th gear which is about 50 mph. This my first overdrive trans and its all new to me. Any info is welcomed. Thanks. Roger
Almost the same but different. I have a lockup converter with a 700R4 behind a 464 and feel the same thing but only down low in RPM when lugging the cammed up engine. (Something I don't do). I wouldn't think you should feel anything at 1700 RPM (I don't). Might be a spark plug misfire or bad pug wire, or arcing distributor cap. Or maybe a timing issue, (too much) causing the engine to surge. Hopefully one of the other guys will jump in with some ideas. I would bet a spark related problem is what you will find. It should be running smooth by 1700 RPM. Mike D.
Mike now that u mentioned it, it does feel like a slight ignition miss. but why would it go away when I unlock it ? Could the power source I'm using from the fuse box be causing it in some way ? I don't remember right off hand what circuit I ran my add a circuit to for the switch. Roger
At that RPM, with the engine solidly affixed to the input shaft all the way through to the rear tires on the ground, you will feel it. You have the same mechanically solid drive line of a stick car. With an unlocked torque converter, it all smooths out the pulses of the engine. At 1700 RPM with one dead or down cylinder that is about 2 times per second. It doesn't take much to make it less than smooth. One easy thing to try is remove the vacuum advance hose and plug it for a test drive. That might be too much advance at that RPM causing a surge or misfire. Mine does it too but only at 1,300 or lower as I'm slowing down. Lockup kicks out at 1,000 RPM when it shifts to 3rd while slowing down.
I ran into the same issue when I put the 2004R in mine. The car lugged badly at 55mph in OD but was fine on the interstate at 70mph. In my case I stepped up the rearend gear ratio. Problem solved. Something to think about for the future, step up to a 3.73 or 3.90 gear.
After reading your replies Bill and Greg the lugging definitely describes the problem. My engine is 572 HP and 574 LBS.FT. torque all in at 5600 rpm and 4600 rpm respectively so I may not be running enough gear for this engine and trans combination for sure. Does running the converter unlocked at highway speeds cause any significant problems. I ask this because new gears for the 9" Ford Detroit Locker I have in the Regal will have to wait till next year. Thanks guys Roger
Does it do OK at hiway speeds above the 1700 range? I would not set out on a long distance drive with it not locked up but if you aren't going long distances, you should be fine. Just be sure you have a good cooler so it doesn't overheat.
Yes it smooths right out above 1700 rpm at speeds above 65 mph or when I switch it off lock up at any speed. I do have a very large aluminum trans cooler and no long trips will be taken so over heating shouldn't be a problem. I do believe now a gear change is in order. The engine was set up on the dyno by Jim Weise so I don't think a carb adjustment problem or timing is the reason for the problem. Thanks roger
Dyno testing does never guarantees good drivability. Particularly at the lower rpms where the dyno isn't testing. I'd check the timing at 1,700rpm and see what it is. I spent lots of hours messing with mechanical and vacuum advance parts trying to get the timing where I wanted for driving and WOT, because these old distributors just were never designed for overdrives' low rpms and high wind resistance(load). RPM and vacuum are low so timing tends to be too low. I'd throw 5* more advance at it as a test and see if it goes away. Its a free test, just some time. But being sub-2000 rpm, I'm really thinking it's a lean miss and needs more fuel. I run 40*-42* of advance at 2,000rpm and cruising speed engine load and up around 50* at my current 2,300-2,400rpm cruising speed.
This is a good idea I'll try it and see were its at. All I know about the timing is that it is 34* total advance. But I still don't understand why it goes away when lock up is off. If its timing and fuel wouldn't it persist any way ?
An unlocked converter makes a very good dampener, plus the engine isn't as loaded up since it's running another 300 or so rpm more.
