working on a '56 chevy here at the shop and the customer wants his wipers working if possible. problem is that he's got a crate 350 in it and an electric fuel pump. to my understanding (limited though it is) with the vacuum wipers is that you need to have the correct fuel pump on there to run them and without it, they won't run. i just want to be sure that this is the case before i sell him an electric conversion for it. also, can you guys point me in the direction of some tried and tested kits that would work for this.
i wasn't sure that there would be enough signal to run them that way. at this point, i haven't even checked out the switch and diaphragms because i don't want to charge him extra time for something that's futile.
On an old Willys I had the wipers were hooked up to the fuel pump. It was an attempt to keep the wipers going when you are in the throttle. It didn't work very well. It was a special dual pump designed for that. As I said it didn't work very well. The best was to back out of the throttle for a moment or 2, then get into it again. They always worked best going downhill under compression. Not my choice for wipers.
i still have the vacuum wippers on my 51 all i did was run the line off of the carb and they work great, even with a fat cam in the motor.
depends on the engine, and the wipers....some vacuum wipers work fine just on intake vacuum, some are ok with a double fuel pump helping them, others just don't work worth a ****. The condition of the whole system is important. Bottom line is you either need to get the vacuum wipers hooked up and working and see if they're ok, or just have him spend the money to go electric. It was pretty common on late 50s chevys that 6 cyl cars got vacuum wipers, 8 cyl got electric.
make sure you squirt some light oil ( 3-1 ) in the wiper motor to lube the flapper.They dry up with age and don't seal too good .When acelerating with a big cam you will not have enough vacuum available to work the motor so make a small vacuum chamber to go in the line to act as reservoir for when the pedal is mashed in the rain etc or going up steep hills.
I've had old cars with vacuum wipers. Even with the correct fuel pump, sometimes at a low idle, they would move super slowly like a snail creeping up your windshield, then they'd start to move a little faster as you picked up speed. It's a little scary if you're stuck in a heavy downpour. If the guy is going to actually drive his car in the rain, he might want to step up to some electric wipers. If it's just for emergencies, maybe stick with the vacuum wipers. If the vacuum motor is really old and leaky, hooking it up to the intake manifold might actually lean out the motor a little when the wipers are on at a low idle.
Even as late as 1970 AMC still used vacuum wipers on some models. I remember seeing them on a friend's '70 Javelin with a 304 and they seemed to work OK, at least they did after we replaced the old motor that had dried out seals. But for the life of me I can't remember if they were plumbed into manifold vacuum or the fuel pump. Maybe it was hooked into both to cover the times when manifold vacuum was low. If you try using engine vacuum make sure you hook it up somewhere below the throttle plates. If you use an off idle port above the throttle plate you won't get much vacuum at idle or during closed throttle deceleration. Maybe a vacuum reservoir tank would help smooth out the operation.
i appreciate the help guys. looks like i'll just sell him on converting since the amt of labor to check out the vacuum system, let alone repair it if needed, would surp*** the cost of just converting over. not to mention the electric system would be safer and more reliable for him. if you saw the subframe welds that the ****tards before me did, he needs all the safety he can get in this thing...
That's what I did.......I'd certainly suggest it. Bolts right on and cheaper than any of the other electric options.
56' Buick...Have done the Fuel/Vacuum pump and off manifold...As ClayMart said a Resevoir tank cured the problem...Just my 2 cents. Fitysix
To me at least, electric is a no-brainer on a tri 5 chevy cause they were available new. (of course I drove my 57 for a long time with no wipers) That being said the vacuum wipers in my 49 Hudson work quite well off the intake vacuum.
My 51 Merc wipers worked fine of intake vacuum (also SBC powered) Now the wiper arm shooting off in the pouring rain on the highway? Well...thats a different story all together...
so...anyone got one of those fer me then? i'm going to talk to him today and see what he wants to do. i just don't like charging unneccesary time to my customers.
Check out Mutton Hollow Chevy. http://www.muttonhollowchevys.com/ His price seams really high to me, but I've never priced them before. He's up near Kaysville, so you could get the parts from him easily. I have bought stuff from him at swapmeets. He knows his tri-five stuff and may have a used setup for you. Give me a call if you need any other info. Tom
All of the Tri-Five Chevys I was ever around sourced the vacuum from either the carburetor base or directly from a vacuum port on the intake. They were always fast at idle and creepy slow under acceleration. Electric wipers were optional in most states, California mandated the electric option. The best option is upgrading to electric. Newport Engineering offers a really slick electric wiper kit that is a direct bolt on that takes less than an hour to install. It uses all the original wiper transmission. It's a really good quality upgrade.
I bought an electric wiper motor off ebay for around $100. There are about 15 of them for sale now. It's a 10 minute swap and uses the original switch/cable.
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