 toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
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01-02-24 04:58 PM - Post#2865505
I'm trying to set-up the power brake booster on my car with a hold-off valve as shown in the "1968 Fullsize Chevy Assembly Manual" pages 344 and 345. I bought a kit with a variety of flare nut sizes, including fittings for both 3/16" and 1/4", but the problem is there are fittings for both 3/16" and 1/4" which fit each position.
Those sizes are close enough that I cannot tell what the mating "cones" are sized for in the master and the hold-off. Maybe it will become obvious when I double flare the lines but does anyone know what the lines sizes should be?
I bought the hold-off valve from Right-Stuff-Detailing" before they became part of the PUI group. Prior to that acquisition they had a great technical section on their own website but it seems like after the acquisition a lot of the old information is just gone.
This is an image with their hold-off. I think the photo was for Camaro. On the Impala the distribution block looks like the same PN but the Camaro has the distribution block laying on its side compared to our cars. I think the line routing for the rears in the photo is actually wrong. The entrance from the master should go into what would be the top if the distribution block was standing up like in the Impala.
Thanks,
Scott
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toro455
"9th Year" Gold Supporting Member
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Loc: Western NY
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01-05-24 08:18 PM - Post#2865631
In response to toro455
My latest realization was that I should have test fit the hold-off bracket. It turns out that the tang on the bracket hits the master cylinder mounting flange. The Right Stuff PV68 bracket looks just like the one in the factory assembly manual photo but it hits the edge unless the hold-off were to be rotated to the point that it looks obviously wrong. If the bracket flange, the booster bolt goes through, was around 3/16" to 1/4" in taller the tang, immediately after that bend, would clear.
Even the factory assembly manual makes it looks like it might hit the master mounting flange so I thought perhaps the original master cylinders had a partial hole for the tab. To be correct the hole would be so close to the edge though that I cannot believe that's true.
I thought about removing about 2/3 of the tang width but it's already small. I thought about using a die grinder on the flange of the master, or cutting the bracket flange off and raising the hole by 1/4". A friend also thought possibly I could bed the tang on a diagonal.
Of course all my parts are now painted and cleared over the base so not too happy but I shouldn't have trusted aftermarket parts even if they looked perfect.
If anyone still has this set-up it would be interesting to see some close-up photos of where the bracket mounts on the master flange.
And for what it's worth there is a front line in the Right Stuff kit I bought. It's 3/16" for the front position of the master to the hold-off valve. It's correctly shaped but it's about 2 inches too long where it goes back towards the hold-off valve. I've tried double flaring stainless with hand tools and it's not easy. I need to check to see if the flare they have seems to fit the master as a second check.
Scott
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 59fins
Member #212 "23rd Year" Gold Supporting Member
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Age: 64
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01-09-24 06:24 PM - Post#2865775
In response to toro455
The pic is wrong for big car, the mc is Corvette I believe, the booster didn’t have the “Delco” stamp till 69’ I believe.
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59fins
Member #212 "23rd Year" Gold Supporting Member
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01-09-24 06:28 PM - Post#2865776
In response to 59fins
There are 2 different brackets (or more) for that valve, and should be phosphate.
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toro455
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01-09-24 07:08 PM - Post#2865778
In response to 59fins
Thanks Bill!
It looks to me like the front line is 3/16" and the one going from the rear of the MC to the distribution block is 1/4". That helps. Thank you! I should have the 3/16" line is a couple of days hopefully.
For the hold-off bracket, I used a mix of paint which looks a little like the chromate yellow coating and then I cleared it. I don't mind taking some artistic freedom with that detail 
Interesting point on the Delco Moraine stamp. The booster I bought doesn't have a stamp. I also bought the bulged MC, dual bail, because it seemed like that was the original look. I didn't see the version with the bleeders on the MC until I bought mine but not a big deal to me.
Scott
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59fins
Member #212 "23rd Year" Gold Supporting Member
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01-10-24 02:47 PM - Post#2865808
In response to toro455
When I switched to disks in about 2010 ish, I bought the same thing thinking that on the mc, the mc I have is close to original but again does not have the machined surface on the the front, late 67’ and 68 had same mc. I have a friend that has the delco books and did a ton of research! plus based on examples with original mc’s still in cars (which is hard) Casting #’s and dates. his is and early 67’ and found some.
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59fins
Member #212 "23rd Year" Gold Supporting Member
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01-10-24 03:06 PM - Post#2865811
In response to 59fins
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toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
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01-10-24 09:27 PM - Post#2865822
In response to 59fins
Great information Bill. Thanks!
That phosphate type finish can be duplicated pretty closely by taking steel, lightly surfaced rusted all over, and soaking in 10% phosphoric acid. I'm sticking with my goldish paint mix.
Scott
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toro455
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Posts: 1392
Loc: Western NY
Reg: 06-15-02
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01-11-24 08:36 PM - Post#2865861
In response to toro455
The 3/16" line arrived yesterday and I bent the line tonight for the front MC position to the hold-off entrance. Before I did I looked at the MC and hold-off mating geometry for the double flare. I really think both front and rear positions are identical. It seems strange because the Right Stuff Kit has a 3/16" front line. It's made for the hold-off system but it's too long. The photos Bill posted clearly look smaller than the 1/4" in the same photo.
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59fins
Member #212 "23rd Year" Gold Supporting Member
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01-16-24 10:56 AM - Post#2865987
In response to toro455
I believe the tubing was bought from “In In Line Tubing”, pre-bent, however I believe they will only sell the whole front end brake lines now, therefore, more pricey ????
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toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
Reg: 06-15-02
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01-16-24 11:04 AM - Post#2865988
In response to 59fins
Bill,
Good to know. Some places are easier to work with than others but possibly Inline would sell it separately despite not listing it. When I bought an entire line set for my 2003 Sonoma, brakes and fuel, they were great to work with (almost 10 years ago I guess). Recently, when I asked about body mounts, I was so turned off by Inline the thought crossed my mind that I may never buy from them again (~Feb/March 2023).
Scott
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59fins
Member #212 "23rd Year" Gold Supporting Member
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01-16-24 02:45 PM - Post#2865997
In response to toro455
Scott,
I would be surprised if they do according to a friend of mine that put several of these sets together. And Just like most companies looking for a way to get more out of you and charge more and more shipping, cause the piece you most likely don’t need is larger!
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toro455
"9th Year" Gold Supporting Member
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Loc: Western NY
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01-20-24 11:47 PM - Post#2866126
In response to 59fins
Bill,
Do you know if the rubber cap on the back of the valve is meant only as a shipping cap or if it's meant to stay on the valve; possibly to help keep moisture away from that button on the back? I assumed it was just a shipping cap so I removed it.
I don't even recall if the first one I bought had that cap.
Scott
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Shepherd
Valued Contributor
Posts: 3499
Loc: Lake George, NY
Reg: 11-11-15
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01-21-24 11:47 AM - Post#2866142
In response to toro455
Put it back on, weather seal is it's function.
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toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
Reg: 06-15-02
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01-21-24 02:46 PM - Post#2866148
In response to Shepherd
Ok Shepherd will do.
Thanks!
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toro455
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Posts: 1392
Loc: Western NY
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01-23-24 08:49 PM - Post#2866236
In response to toro455
The cap is back on and I removed the 3/16" to inspect the flares. It looks like they are sealing so I reassembled it. Hopefully there won't be any surprises when it actually sees fluid.
Scott
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59fins
Member #212 "23rd Year" Gold Supporting Member
Posts: 2516
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01-28-24 08:45 AM - Post#2866367
In response to toro455
Shouldn't be, I believe that is to keep dirt and weather out, it defiantly needs to ben there
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toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
Reg: 06-15-02
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08-29-24 05:56 PM - Post#2873242
In response to 59fins
I finally got the lines going from the upper area to the distribution block installed.
I was able to use the "Right Stuff" line as-is for the rear. Mostly. I had to shift things a bit but once I did it fit quite well. That's a 1/4" line. I just hope I would have issues with the stainless end-forms leaking anywhere I used stainless... The CuNi is so much nicer to work with.
The line going from the hold-off to the front seemed to be 3/16". I ended up hand bending that line and then I slipped stone-guard over it. I even gave it the same number of turns that the Right Stuff part had. The biggest issue with the Right Stuff part may have been due to the bracket PN the aftermarket is selling. Looking at the images posted above the bracket which places the valve at a less-square angle probably would have placed it in the correct position to use their line. I had to make almost a 180 degree bend and I had to make it tight to the fitting because the inner fender support bracket is close.
I removed my MC to hold-off line and installed the front line first. I did that because it really looked like it was designed for that MC to hold-off to go through the center of the front line loops.
It looks better live but I think it came out very nice. I wish my hold-off bends were a little smoother but the lines are now all installed so I wanted to follow-up here.
Thanks for the help,
Scott
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59fins
Member #212 "23rd Year" Gold Supporting Member
Posts: 2516
Age: 64
Loc: Surprise Az USA
Reg: 04-07-00
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08-29-24 07:20 PM - Post#2873245
In response to toro455
Glad you got that together Scott.
Them darn brake lines can be such a pain.
All sealed up I hope.
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toro455
"9th Year" Gold Supporting Member
Posts: 1392
Loc: Western NY
Reg: 06-15-02
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08-29-24 07:51 PM - Post#2873246
In response to 59fins
Thanks Bill! I might give all of the stainless connections a back-off and tighten sequence before filling it. I have so much more to do filling isn't a huge priority immediately.
After I replied above I looked at the nice photo you added of the 67/68 hold-off versus the '69 and I think that other Right Stuff line would likely work with the '69 valve. The Right Stuff line and the one I bent look very similar with the exception of how much of a bend, degree of the bend, for that first bend near the hold-off.
Scott
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