Both of these items are designed to take full advantage of "uninterrupted" vacuum, without any pulsing or varying of the vacuum. Plus, in most trans. vacuum lines, the factory original line is small at the carburetor, or otherwise, restricted. The wipers need full. So, I'd say no. Pull from the plenum separately for both. Mike
It all comes from the same source. You might want an ac***ulator tank. Sent from my iPhone using H.A.M.B.
I would second the vacuum tank or elevtric wiper motor ideas. Last few weeks we've had a bit of rain and quite a bit of fog here. Those days, I ride my motorcycle to work. My hand wiping water from my helmet visor is much better than the vacuum wipers in my truck. I have been debating ordering a tank or just switching to an electric motor. Tired of the wipers not working unless I'm stopped idling. It is my daily though so it's a necessity. Good luck.
Have you tried lubing the wiper motor and wiper shafts? I did this to my vacuum wipers on my 49 Buick and they work great.
Vacuum wipers ****! Literally! None of the cars/pickups I have with vacuum wipers really work worth a darn. Dave
My concern was that turning the wipers on might reduce vacuum and cause the transmission to shift since there is no mechanical kickdown linkage on the TH400.
The wiper motors are exposed in the cab of the truck and I just like the looks and novelty. If they need a pump of the pedal once in a while to swipe, like my Olds does, I'm good with that. I just don't want the trans to shift when the wipers steal vacuum.
Turbo 400;'s are electric kickdown in the side of the case. and a switch at the pedal or carb linkage.
Out of pure curiosity, not knowing what the profile of the vacuum through the cycle of the wipers might be like, you could rig up a gauge to find out. I'd wager if the demand for vacuum was steady they'd be a fair chance that there wouldn't be an effect on the transmission. Having said that there would always be an effect when the wipers were first switched on but how how that would work out is uncertain. The more I think about it the more I think its a crazy idea, but possibly a fun lockdown, mythbusters type experiment!! Please let us know the outcome!! Chris Sent from my SM-T515 using The H.A.M.B. mobile app
They may share the same vacuum area under the throttle plate, but each should have its own supply line from the vacuum source. If you add a "T" from one line, you run the risk of reducing the available vacuum to operate both vacuum needs, unless the line from the source to the "T" is large enough to provide enough volume to supply both needs. Weather or not the motor is capable of providing enough volume to serve two vacuum needs at the same time is a different question. Gene
I'm running a MAP sensor in another OT build. The intake uses unshared plenums with no balance tube. Due to design my engine builder states that I need to access full uninterrupted vacuum rather than shared interrupted vacuum. Would you draw sufficient vacuum from a manifold 'T' without impacting on transmission at the same time? Does the car have power brakes? You could run 2 x separate lines and using a vacuum gauge, see how much Hg each line pulls?
I doubt it. The vacuum lines that operate the transmission and wipers aren't open to the atmosphere, they are closed. The amount of vacuum will not change by adding attachments. Try this, hook up a gauge to as many vacuum sources as you can. They will all read the same. They all have the same 8 cylinders pulling air. No need to split the two lines for different functions.
I've got a vacuum wiper motor sitting here that I've been meaning to see if I can get to work on positive air pressure, once I'm finished with all this procrastination I need to get done.
Lots of variable here... Including how radical is your 427 , does it build enough vacuum, how much are you going to drive it, etc. I agree with the other posted about a vacuum pump or electric wipe conversion. The vacuum wipers on my 56 Pontiac in my avatar are only there in case of an over zealous revenue generator. Rain-X is my solution since it only gets driven in the rain once in a while. My 2 "one year OT" 66 AMCs offered both vacuum or electric wipers, I have one of each. Since I am parting one out to build the other, I might convert the good one to electric. My OT Catalina conv will get a vacuum pump, I already know my stroker will not build enough vacuum to power the brakes. God Bless Bill https://www.jalopyjournal.com/forum...ar-transport-hauling-open-or-enclosed.614419/
Actually, the wiper motor pulls on vacuum and opens to the atmosphere to return to the resting position. Thus creating a pulse in the little rubber hose to the wiper, That is why you do not want to TEE the line to the transmission. Source of knowledge: A 1957 Cadillac that I absolutely do NOT miss.
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