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Hello, I have just fixed two problems but apparently created a new one. After endless headaches with my rebuilt original Carter WCFB, we put in a new Edelbrock AVS2 carb, which makes Lucille literally purr. However, on yesterday's test drive, she starts off in high gear, and then sometimes suddenly downshifts. Disconnecting the linkage from the throttle/carb to the transmission made no difference. Does this mean the vacuum to the transmission is not hooked up correctly? I do not think we HAVE vacuum to the transmission! It seems we kept everything the same. What are we missing?
Thanks!
Andrew
Even more info please crystal ball is quarantined.
Year:
Model:
Engine Displacement:
Good chance if it's an auto 4 speed its a TH2004R. If true the TV cable adjustment is critical. Get it wrong and it will smoke the trans due to improper line pressures. Do not drive it disconnected. Once you get it in the ballpark this is how you can firm up your upshifts...with small adjustments.
Google TH2004R TV cable adjustment
I notice you posted in other threads that you have a 1951 Super 88. Is this the car you're trying to get to shift properly? If so, I suggest going back to the OE carburetor. The TV adjustment on the linkage can't be guessed at. Like others said you can quickly torch a transmission if the TV is out of adjustment.
I had a 1964 Oldsmobile 98 with the a Slim Jim Rotohydramatic. I installed an Edelbrock carburetor for a short time but couldn't get the TV to work properly so I went back to the OE Rochester 4GC.
You do not have any vacuum going to the transmission on a 51. What did you do with the carburetor linkage from the old carb? As mentioned above it is very critical on the adjustments and the Edelbrock if used as it came out of the box won't work the shift linkage correctly if at all. They can be made to work with work though. Do you have a motor manual for your car, if so you would see how the adjustments are set up. It is not that complicated but would be hard to communicate without pictures. Also as mentioned above rebuild your old carb and eliminate the linkage issue. What ever way you go keep us in the loop..... Tedd
PS. after thought, did the car shift correctly before the swap?
Sorry all, I did not pay attention that I had not specified that it is a 1951 Super 88! Yes, it DID shift properly before the carb switch. My mechanic says he fiddled with it and now has it shifting correctly. We used the existing linkages, which SEEMED to fit spot on. I have not been over there as we are under a Corona lock down, but he is still steadily at it.
Ahhh... a Hydra-Matic 4 speed. I see said the blind man...Pressures are the health of any semi and automatic with a torque converter.
To test simply find the test port and screw in a 0-300 pis gauge and look & compare spec...like taking your blood pressure at the doctor's. All it takes is a few 10s of pounds to do harm.
We also require at minimum one good pic of your 51
Last edited by droldsmorland; March 25th, 2020 at 07:09 PM.
Here is the car, (named Lucille, but then aren't all yours too?) and the carb. It took just a few adjustments by my mechanic to the original linkages, and it now shifts in just the right spots. He doesn't know about test ports, but I just found these in the Shop Manual. How much danger am I in, now that she APPEARS to be back to behaving normally? I have only skimmed the many pages, but is the pressure testing done in the garage or with the car on the road?
Thanks!
Andrew
Hi Glenn/Redoldsman, I am responding to your post elsewhere on this one - Regarding how Michael got the linkage adjusted - Unfortunately I was not there for that, so it remains a mystery! He did not give me much detail, just that the nuts on the linkages had to be fiddled with. (Jaunty75 will like to hear that!) The carb setup was not that different. I am still concerned regarding droldsmorland's post re pressures. Not sure if I can enjoy Lucille or if I need to get her back to the shop to check the transmission fluid pressures first. We are more or less locked down here, but I am enjoying using her for grocery trips, etc..........
The nuts referred by your mechanic are probably the ones on the long rod that goes to the last link on the carburetor down to the transmission linkage. Making this longer or shorter will change the length of time or shortness it will stay in gears, It has it's limits though.Go to far or to short and the transmission will search for a gear or jump out of the gear. normally this has to be sorted out by setting all the carb linkage ahead of it correctly then fine tune it with the long rod. I wasn't aware of the Edelbrock being a direct crossover back in the day we had to fiddle with different linkage adjustment on the carburetor to get it to shift correctly. Glad to see things worked out and I wouldn't worry to much about transmission pressure if it worked well before the carb switch.... Lost in the fifties ...Tedd
Thanks, Tedd, that is what my mechanic said when I passed the message on. It was not altogether plug and play BTW: First it needed a Hedman adapter (2064) for the different bolt pattern and manifold openings. Then the linkages on the Edelbrock hang down lower than those on the Carter, so for clearance, we added a 1" spacer. Still too low. No 1/2" spacers readily available. A second 1" spacer put all the linkages out of reach but a 1/4" gasket did the trick instead! (So now 1 3/4" higher) Then the throttle link connector from the WCFB was too short, but Michael harvested one from a scrap carb and we thought we were in business. That's where I left at the end of the day. When we got together again, Michael had shortened the harvested connecting rod to shorter than the original one was, so he had fiddled with it. This might have been the cause of the transmission linkage issue. We discovered the crazy shifting and I again left Lucille with him, to find her fixed the next day. Yes, he was referring to the nut on the linkage to the transmission. The one closer to the carb is welded in place, but thankfully the further one could be adjusted towards the rear of the car and as I mentioned (so far) Hey Presto!
The reason I posted this and mentioned it on the other 1951 thread is that you would not believe the trouble I had with Lucille dying on me (I was towed five times!) and my previous mechanic came up with all sorts of remedies at great cost which did not fix it, including a fuel pump rebuild, fuel pressure regulator, and carb rebuild. I am hoping this is the end of that particular spate of problems..........
Andrew
I feel your problem is electrical not gas from 1200 miles away, I could be very wrong. As a test you might try jumping a wire from the + side of the battery to the + side of the coil. this will bypass the ignition switch and the connections at the starter and the coil. Check to see if you have power at the coil and points. If yes try and start the car, if it starts you most likely have bad connections at the starter or the ignition switch If it starts then quits it could be your coil. You will need to disconnect the jumper wire to shut off your car so I wouldn't go for a long ride. My guess it is your ignition switch or the wires going from it are corroded or have broken some where and separate when they get hot or vibration get to them..... Let us know how this comes out..... Lost in the fifties ...Tedd
As a novice I am open to all the advice I can get. I neglected to mention that a new ignition switch was one of the earlier fixes. So far no problems, but I will add what I need to do this jump to my onboard supplies in case I get stuck again.
Thanks!
Tedd, will a jumper cable work? If not, what gauge of wire would you recommend?
Last edited by aljmann; March 31st, 2020 at 05:45 AM.
Reason: additional question
March 24th, 2020, 06:48 PM
.... Tedd
