Ok so I'm having problems here I've added disc , master and booster from a 70ss chevelle I tried and tried to bleed all 4 but only was able to bleed front . I called inline tube and ordered the disc drum block needed for the swap ( haven't installed yet) the guy told me I will need to order a couple lines too I'm guessing for the front which didn't make sense to me . Can someone tell me if this is right or do I just swap the block and it'll be fine? Also in future ill be adding headers I was told to move block on top of frame ; will the lines reach ok ?do I hook all lines up and just force it over on top of the frame ? Inline sent me a mounting bracket I was thinking maybe weld it to top of frame then stretch it all over. Please advice here would be great.

 

I will be working through your issue this weeked on my 68. Just switched from drum to disk upfront (disks from a 69 Cutlass) and I have Hookers. Moving my prop block back and anticipating rebending both front lines and the two leading down from the master. I measured the oldlines and even if, I straighten out some of the bends it's cutting it too close (won't alow for any flexing). So, I bought some bulk hose and it's time to get out the flair kit and bender.

Bill

 

First, do you have the correct proportioning valve setup or not? You can either use the drum brake distribution block on the frame with a separate metering valve, the way the factory plumbed the 1967-70 disk brake cars, or you can use the combination valve that replaces the distribution block, the way the 1971-up cars are plumbed. Either way works.

If you have the correct plumbing and still can't bleed the rear brakes, the first thing to check is the bleeder screws. I've seen the holes in the screws blocked with rust and dirt. If the screws are open, use a piece of copper wire to poke in the bleed hole in the wheel cylinders. I've also seen these blocked with rust. Of course, if you find that much rust in the wheel cylinder, you might want to replace the whole cylinder.

If that doesn't fix the problem, the piston for the differential pressure valve in the distribution block has been pushed all the way to one side and is blocking the rear ports. If you are replacing the distribution block with a combo valve, that will fix the problem. Just be careful not to jam down on the brake pedal when bleeding the brakes. Press slowly and firmly to avoid pushing this piston too far.

 

You need brake lines for front disks and also the brackets that secures the brakes hoses. They are positioned differently than drum brake cars. Maybe you can re-bend the drum brake lines, but I wouldn't try it, especially with 42 year old lines. Some guys bend their own lines, but I bought the 4 front lines.


Also, I removed the inner fender, which makes attaching the combination valve to the frame a lot easier. On the 72, it is located on the inside of the frame rail. It is close to the engine and exhaust down pipe. It is pretty tight with the engine in the car, but do-able. Crows foot flare wrenches (7/16 & 9/16) also were a help tightening the lines to the combination valve.

 

Yea I've got a set of hookers too but motor and eng bay looks too rough to put them pretty headers right now . Plan to pull motor and clean things up next year. I really hate to have to make new lines but if it comes down to it.... Let me know how it turns out for you.

 

Yes joe I bought combo valve befor I realized I could use the orig 70 hold off but now that I have the new one I might as well use it per 71-72 being correct. Should there be enough slack in lines to relocate to top of frame ?

 

Brown what is the diff between drum lines and disc lines ? I'm trying to remember if I got the complete lines up front on the 70 chevelle or not and if I did where they are 3 years ago and two house moves....ahhhhhh

 

I've done that by rebending the lines (without disconnecting them ). There is JUST enough line length.

 

1970 will be different than 71-72 because of the separate hold off valve. 70 uses 5 lines, 71-72 uses only 4.


The drum lines are shaped differently because they attach at different places. Not radically different in length, but different. I don't know if there is enough slack to bend them differently. But unbending and re-bending 42 year old steel lines may prove problematic. Steel lines can rust from both the inside and the outside and re-bending could break or crack them, or weaken them to the point that when you need them the most, they would fail. I bought the 4 lines in 2010 for $65 from InLine Tube. Some guys don't like InLine, but I have never had a problem with them. They are probably more now, but not that expensive when you consider that it may be your life or some significant other's on the line.

 

Regarding Headers the Passenger side was rough (I have an AC car). I pulled my mounting bolts and all the other bolt ons in the way, lifted the engine up w/ the C picker. It took me four damn hours to install them. Going back to the brakes, have both set ups the combo valve and the hold off w/ prop not sure which I'm going with yet. I going to pop off the old lines and use the as templates for new ones (that I will attempt to bend). Gonna leave pleny of slack at the ends, dry fit em at the master and front rubber. Then, I'll hook the rear brake(s) hard line up, pick a place for the prop or combo and put the rest of the puzzle together.

Bill

 

Yea mines a ac car too and from all I heard about header install I'm not looking forwerd to it, a friend gave me a black set of headmans today he had , new in box I might try them after I finish the brakes. Yea I've got both new combo valve for 72 nib and the 70 hold off. I'm like you just gona (wing) it and see how it goes . My brother inlaw is coming over tomarrow and were hot on it as I'm in need of some back brakes lol. Let you know how it goes. I really hope I don't need to buy them disc lines , thread size looks same on new combo valve and the old drum drum that's on it

 

I have heard that this may be necessary on a big block application. On both my '70 and '71 350 cars the headers fit fine with the block in its original location.

 

Oh really

 

This is entirely dependent on how a particular header manufacturer routes the tubes. All are different, so it would help to know who made those sets you installed. My experience with SBO headers has been that the dist block did need to be moved - on a 68 and a 71. That was decades ago and unfortunately I don't remember the manufacturer(s).

 

Joe, it was with two different sets of Hedman Hedders from the '80s / '90s. I just went out and checked the amount of clearance. The rear header tube comes off the exhaust port, drops down with a slight rearward angle, and it is almost 4" in front of the brake distribution block. So there's 3+ inches of clearance.

 

Well I've got a set of headmans I hope they fit without problems

 

Hey bill how'd the upgrade go? Did you get it fixed up without any major hikups

 

Well did not get anything done, the job sent me down to Long Beach for the week....on OT and put me up in a Marriot; can't complain too much. Just got back home a few hours ago, I will keep ya posted.

 

Well it's done! Posted pictures in my album. Two day pain in the ***, with lots of penatrating oil, torch and 46 year road debris in my eyes! Still had to rebend and flair 5 lines. Got brakes now! Used the Bendex combo valve, instead if the hold off and prop, had to move it back a little or it would have been sandwiched between the inner frame and Hookers.

 

I found the hold off and the old line I took off years ago on the 70ss I'm thinking I might slap them on for now till I pull motor then ill have more room to add combo valve and make new brake lines to relocate. So you moved yours back huh? I've heard most just roll it to the top of frame

 

Yeh, I looked at goin up, but with the existing front passenger line and the intermediate line, it required less tweeking to move them back than up.

Bill

 

Update on my swap . I used a combination valve with a couple adapters and used all my same lines just took me 45 min of bleeding and though I've not put it on the road it feels good in driveway

 

I'm in the process of changing my drums to disks. Got the disc set up from an cutlass with the factory set up.(Do not know the year. Looked like a 72) So far I've change the brake hoses that go to the back of the drum brakes to the steel line. I also have the block from that car as well. Have not removed the old one to replace it with the disc block, but will this weekend.. I have Hooker headers that I will install on the car too.