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Many things can change. I bought my 70 with an Olds 260! I currently have a 76 block with 70 heads. What is the big number by 1 and 8 on the cylinder heads?
many things can change. I bought my 70 with an olds 260! I currently have a 76 block with 70 heads. What is the big number by 1 and 8 on the cylinder heads?
No man he called back, vacuum modulator. Took some pics of it doesn’t look good at all. Guy has a liquid seal gasket. But to me this doesn’t look like the on I pulled up online. It’s shifting hard in both speeds.
No man he called back, vacuum modulator. Took some pics of it doesn’t look good at all. Guy has a liquid seal gasket. But to me this doesn’t look like the on I pulled up online. It’s shifting hard in both speeds.
Leaking transmission fluid at this location = ruptured ATM diaphragm. Easy fix.
I realized after a few hours of looking up the transmission parts. They are all fairly inexpensive. Hope this is an easy fix like mentioned. Thanks for all input
Yes, a ruptured vacuum modulator will cause rough and late shifts. I also had that symptom from the governor on my 1970 TH350. It acted like it had a shift kit. I changed the governor and added lighter weights for higher rpm shifts. It shifted like mush at part throttle after that, weird. I used that governor with an adjustable modulator in a 1985 TH350C and it shifts normal. For the leaking rear seal, a tail shaft bushing and new seal should fix it.
True enough. I should probably have typed out ATM (Automatic Transmission Modulator), which is how I usually reference the transmission vacuum modulator.
The OP (Jay) stated he didn't know which transmission he had and I can't tell from the picture. With that said, you can identify (to some degree) whether it's the 350 or 400 via location of the ATM.
The first image is the ATM location for the 350 transmission, second picture ATM location of the 400 transmission. Follow the modulator pipe from the engine intake manifold, it traverses downwards alongside the transmission oil filler tube, then snakes rearward towards the back of the transmission until it attaches to the ATM. Review the integrity of the ATM.
Good news and bad, good thing- vacuum modulator is good. Purchased one but 1/2 bolt for clip stripped to hell. Owner previously for whatever reason ran 1/4 rubber tubing all the way to carb!! Hose was dry rotted so I replaced and it shifts perfectly. Bad news is I still have that slight leak at the rear seal. Not tremendously worried, but I will tend to it later. Thanks again for all input and advice— New 71 Olds owner!
August 7th, 2019, 05:56 PM
I should probably have typed out ATM (Automatic Transmission Modulator), which is how I usually reference the transmission vacuum modulator.
