demetri

Hey guys, I was playing with the 440 again (68 a bit worked up in an Imperial). I was trying to do a quick acceleration test, and pulled the shifter to 1st at around 20-25 mph. It refused to downshift. Then, as I was approaching a stop, it did somewhat violently downshift (i.e, shifted to 1st sooner than if the shifter was on D or 2). Then, upon acceleration, it shifted again on 2nd even though I held it locked to 1st.

The kick down linkage is still not properly adjusted yet (I have reached the limit of the adjustment) but the manual shift used to work.

I don't know if the following helps in the diagnosis, but when the transmission was reassembled (about 400 miles ago) after its rebuilt, the Low 1 was not working at all. I had the rebuilder readjust the linkage, and then it worked, until now. I actually had this not work for me once about a month ago, but then it worked again, and I forgot all about it.

While I was driving today, I suspected that may be the linkage is still marginal, and I pulled down harder, no difference.

Any thoughts?

RacerHog

Unless you install a style of shift kit that allows you to over ride the governor with manual shift the governor will over ride it to shift...

Some Reading for you:::::http://www.transgo.com/

demetri

Just a week ago I could shift this car manually, and I could take 1st gear all the way to 5000 rpm.


On the other hand, I also recently had to readjust the kick down linkage because it was interfering with the valve cover and was not allowing WOT (this Ederblock AFB has a throttle opening rate that does not seem to be consistent with the stock kick down linkage). I tried to compensate by extending the vertical part of the linkage, but run out of threads. I think I am close to where I was before, but I cannot be certain. Could that be causing the premature shift? I am wondering if I should find a way to extend this further, may be that will cure the premature shift?


Wondering how can I extend that linkage ...

moe7404

a quick adjustment , be sure the carb is at curb idle. cover the opening in the head under the carb with a rag, so you dont loose small parts. take the clip and washer, off of the carb pin. and the spring. slide the slot off the pin and pull it forward. shorten or lengthen the slotted sleeve so the slot just slide over the pin. then make it longer by 2 to 5 turns. longer will shift at higher MPH. do not go more than 7 turns, that will up set the trans pressures. this is quick adjustment the full factory adjust is not allways needed. can be found in the factory service manual. just for info. the slot is if in ice weather and the linkage at the trans gets jamed with ice or snow, the carb will return to idle

moe7404

TO: demetri i had a 65 300 L. and the shifts for street driving was to soon at light throttle, and to high the WOT. i took the bell crank at back of the engine, and made the rod hole taller by 1 1/2- 2 inchs. it ended up staying in gear longer at light opening. and short shafted at WOT. with 413 cubic in shifting at 4,000 RPM on the street was more than enough power.

demetri

On second thought .... low 1st is also for engine braking, so it should stay on 1st gear even if with completely closed throttle. But I have read somewhere that in the push-button transmissions prior to 64, you could not hold 1st but you could 2nd. The 68 should not be like that, and it did not used to be like that until recently ...


d

demetri

Moe, thank you for the information. That's what I was doing. I kept on extending this horizontal rod, and the car kept on shifting too early at part load. I eventually ran out of threads, and bought a bolt with the same thread size, attached it on the rod with hose clamps, and bolted the slotted sleeve at the end. As I kept on extending that, I reached the point where the part load shift was OK. But the transmission always up shifted way too early at WOT. That was OK, because I was using the manual shifter. Then, I realized that the over extended horizontal rod was now preventing the throttle plates from opening (see my thread on 440 build for Imperial). That forced me to shorten the horizontal part again, and try to extend the vertical part to compensate. It worked, to some extend. But I can no longer hold 1st gear manually any more. Not certain if the two are related (i.e., the inability to hold 1st may be some other recent malfunction) but it might.


I suspect many of you have these adjustments many times before, so you may have some ideas.

Gorts 5th

There is a governer piston in the valve assembly that has control of the shift.point and point of down shift ....the piston must ne modified to down shift into first at any rpm and to hold it there.
PACT.com ...has kits and the part if you want to go the inexspensibe way nut the kit is the best way to improve your trany performance.

RacerHog

That's not its purpose..... Get a trans book and start reading... Governor over T.V..

Your trying to make it do something its not intended to do.

Once you under stand what its purpose is. Then you will be able to get your head around the adjustment and what needs to be done in side the trans....

But my suggestion would be... Pull the Governor out and plug it so it cannot over ride the shifting valve. Then you can keep it a little more consistent...

Just My 2 Cents

demetri

Thank you guys for your input, but I still don't get it. I just read the owners manual on the 68 Imperial. It mentioned that 1st gear can be used for engine braking under 25 mph, and warned against holding it at any speeds above 40 mph in order to avoid excessive rpm. That seems to indicate that it will hold 1st gear indefinitely. In fact, used to do that just two weeks ago, and I can do this on my other car.


And for reference, when I shifted from 1st to 2d manually at 5000 rpm, this corresponded to almost 60 mph real speed (speedo showed almost 70). So, the owners manual is a bit conservative o the 40 mph, as expected. I think they did not want people to drive around with the transmission locked on 1st.


I think that the governor options and upgrades you guys are talking about may be needed for earlier model transmissions, but were stock in 68. It is also clear from multiple road tests of the period that the manual selector over rides the governor on the stock set up in anything big block 727 after 67.

moe7404

IMHO. holding a stock trans to RPM levels higher than stock is asking for trouble. and generally a stock big block in the 60s will level off the RPM when the hydrolic lifters float. chrysler used it as built in rev limiter to reduce warranty clams. back to my first statement ALLWAYS keep stock parts to stock RPMs. IMHO 1,000 RPM over a chrysler stock engine is pushing your luck. .

demetri

Thanks Moe. The cam I have in there is comp cams 268-280, .477-.480 (plus some head work). This is a few steps up from the stock HP cam. The advertised range of this cam was from 1600-5800 rpm. I have never revved the engine over 5000 rpm, and do not really plan to. I think that the stock red line with the HP cam was 5500. Again, I do not really plan nor need to rev it that high. For reference, with the gearing/tires the car has, 5000 rpm corresponds to about 58 (70 on the speedo), 103 (110+ on the speedo), and 150 mph for 1st, 2nd, 3rd. These are essentially shift points, not cruising conditions that you would hold for any extended period of time. So, the 40 mph that Chrysler suggested to not exceed for extended periods on 1 made sense, and what I am saying is not in conflict.

Gorts 5th

That is a good cam..
did u do the kit or just the cam n lifters?

demetri

Got valve springs too. See my thread "440 build for Imperial" on the engines page. I also got the larger valves and a bit of head work on the 906's.


I am impressed by how much low end this cam allows. I am doing final adjustments to carburetor mixture and final timing, and I am getting a feel of the upper range of the whole setup too. I have a feeling that this engine build will be very well suited to a heavy car.

moe7404

comp-cams is a good outfit. many years ago i got to dial in one of there cams. with my 2" indicator. i checked it very closely. and it was with in .001". basically dead on..

TVLynn

My guess ? You are using 2 bbl linkage on a 4BBL installation !!!!

demetri

No, Imperials only came with 4 bbls. In fact, they only came with 440's, which also only came with 4bbls.


But thanks for trying, it may be something really simple.


I readjusted a bit the shift linkage, and may try car tomorrow again. It seems to feel better on the "click", but it may be an illusion. There was not much slack on the linkage to really take out.

demetri

Turns out that the tiny amount I took off the shift linkage made the difference, at least today when I tried it. I could hold manual 1st to 4500 for a brief tuning test. I actually managed to rev 2nd too to 4500 until traffic blocked me, I was hoping to take 2nd to 5000.


The part load linkage still shifts a bit too early, but somewhat acceptable. I will have to extend the vertical link, but not clear yet how. An allthread section and a long nut? Anybody knows off their head the threads of the vertical section? My guess is 5/16-24.