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When I rebuilt my 8BA I added a PCV valve which takes up my carb vacuum line. Now that I’ve added a vacuum boosted master cylinder, I decided to add a vacuum pump and relay but of course I have no diagram.
Can anyone educate me on relays and help me wire it? I have a one wire switch, two wire pump and a 4 wire relay with terminals for 85-86-87-30
The vacuum connection on most 8BA/8RT engines for the wipers is inadequate for power brakes. Big-truck manifolds had a separate connection with much larger capacity specifically for power brakes, see picture below (plugged connection). I think you'd be better off using manifold vacuum for the PB's than a pump.
It wouldn't be difficult to drill and tap the back of the manifold to add the brake nipple. Easier than mounting pumps and running wires, and be more efficient.
It wouldn't be difficult to drill and tap the back of the manifold to add the brake nipple. Easier than mounting pumps and running wires, and be more efficient.
It is actually not that easy to drill, first because of the size of the main threads, second because two holes need to be drilled at an angle from the main bore into the throttle bores. For sure you'd want to have the manifold off because of shavings, but also to be able to jig it up in a drill press. Getting a different manifold that has the tap would be cheaper except for the shipping. But it's a golden opportunity to get an aluminum manifold at the same time.
If me I would go for a belt driven vac pump like Power stroke diesels they are small in size.
I am not up on the PS diesel's but are you sure that belt driven pump is not power steering and the brakes are Hydro Boost.
I had a 86 Chevy K5 full size Blazer with the 6.2 diesel and the power brakes were Hydro Boost run off the power steering pump.
It was not fun when the booster pump seal let go and pumped all the steering fluid inside and soaked the rug
BTW the 6.2 did have a vacuum pump for HVAC but it was in the place where a dist. would have been installed if it was a gas motor.
It worked like SH**
Dave ----
What brand of vacuum pump do you have.? Are you sure it needs a relay. I just put a new one on my truck. All it needed was power and ground.
I agree with FuzzFace2, that sounds like a hydroboost on the diesel truck if it is belt driven.
The Leed System Installation instructions call out an inline fuse, which is great. It also states that it requires 15 Amps of switched power, a seemingly perfect use of a relay. There is no relay internal to the unit; that is impossible with the only power and ground wires the unit has.
The Leed System Installation instructions call out an inline fuse, which is great. It also states that it requires 15 Amps of switched power, a seemingly perfect use of a relay. There is no relay internal to the unit; that is impossible with the only power and ground wires the unit has.
It's a world beyond me. I know that I bought a black bandit system from Leed systems and installed it. Had an inline fuse that I cut out because I had a 15 amp fused circuit from my panel. The other wire I ran to ground. Everything else is inside the "can". I did not open it up. But I know that my brakes have been amazing since I put this on and junked the old brake booster that my mechanic put on and charged my outrages money for. Perhaps there is a relay inside but at this point I am not opening it up to find out. I know it works and I am super happy with it.
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