Aceshigh

Drivers side inside frame rail I have some kind of block attached to it.
It's literally all the way down the firewall , just before it goes under the body.
1 line goes in for the rear and 1 out.
2 lines go in for the front and 2 out.
1 electrical connection.

Now I read MDMechanic's details HERE, but I'm not quite sure if this is doing any proportioning or not.
I just put a rear disc conversion in last season and I was having a HELL of a time getting the rears to
lock up. I already swapped in a 1 1/8" Disc/Disc 79 Corvette Master Cylinder, as well as an adjustable
prop valve which does nothing to better it.

This is my engine bay and you can BARELY see the piece I'm talking about behind the K-member on the
drivers inside frame rail. Anyone know if this is a prop valve of some kind or not ?? Just trying to determine
if I need to remove it, and connect the lines, or keep it as is.

I was told upgrading the rear lines to 3/16" would also help pressure.


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Aceshigh

Ahhh.....disregard.
I found it. Just a distribution block with no proportioning so I'll put it back in place.

http://www.opgi.com/product.asp?c=Br...981&yearrange=

don71

I'm thinking thats a combo valve in 1970. So it does more than one thing.

You mentioned you installed a adjustable proportioning valve. Did you install it before the factory valve or after it? The factory one might be over-rideing the one you installed. Maybe thats why you cant get the rears to lock up, though I don't know why you would want that to happen.

Aceshigh

I should clarify what I mean....

When I say "Lock up" , I meant up on jack stands, in gear, letting the tires roll.
I hit the brakes and the rears don't stop immediately. In fact, they don't stop hardly at all.
It just slows down VERY VERY slowly.

So I was having a proportioning issue still even after several bleedings.
I wasn't sure if I needed 3/16" brake line ran to the rear, OR if this distribution block was giving me headaches.

My Adj prop valve is by the MC by the way.

svnt442

Ace it's just a distribution block. The proportioning valve was a separate valve mounted just below the master on the power brake booster. The combo valve didn't show up until 1971.

While you have everything out you should relocate that block to the top of the frame. I don't know what kind of clearance issues you might have with headers with the LS swap, but with the Olds engines it's a must to move it or you will boil the brake fluid.

Aceshigh

Hell it's been there since production and I had headers with the Olds 350.
So if it's a risk of boiling the brake fluid.....it's been doing it since those
headers were installed God knows how long ago.

So you think it would be better suited just relocating it up on the horizontal
part of the frame instead of the vertical side ??

Boldsmobile

Left mine in the stock location after i added headers and havent had any issues with my fluid.

oldspackrat

Ace,
I talked to you last week about a similar issue on my '70 with rear disc brake conversion. I removed the metering block that hangs off the side of the master cylinder. I am told that the metering block delays the application of the front brakes until a certain (low) pressure to allow the rear shoes to engage into the drums. I bought a brake pressure gauge from SSBC that you screw into the bleeder valve of your calipers. I'm getting 600 psi at both fronts & only 250 at the rears. I've read you need anywhere from 600 to 1400 psi for the calipers to really grab. I've also read the dist. block on the frame restricts pressure to the rear drums to 250 so as not to lock up the drums. Seems to make sense, as that is the reading I'm getting & my rear wheels will not lock up & do stop VERY slowly also. My plan is to somehow find/fabricate a dist. block that allows full pressure to the fronts & rears & then put a adjustable prop. valve in line to the rears after the dist block. I might then need to get a double diaphragm brake booster to provide more pressure.
This is not as easy a conversion as I thought it would be, but when it comes together, I'm sure I'll be happy with it.
Good luck.

svnt442

The general consensus is to move it. It's going to depend on where the headers sit in relation to the block. If it's too close then move it, if not don't.
And I was talking about moving it to the top of the frame instead of the side.

joe_padavano

X2. Every header manufacturer routes tubes differently, so what worked on one car may or may not work on another with headers from a different manufacturer. It's no big deal to relocate the distribution block. I've done it without even disconnecting the lines.