As Harry said, if it stopped before the swap then shoe arcing isn't a problem. Did you change out the shoes and drums when you swapped out the MC? Sounds more like the wrong MC or it is not bled properly. Installing a proportioning valve will give a better braking bias. We can only guess at this point, untill you give us more info.

If I may add a few things, comments. If you installed a non power dual master cyl find out if the master has the residual valve built in. Some are in the master and some in the proportioning valve. If not get a proportioning valve for the car you got the master for. eg: 71 nova/ chevelle with a manual master. Check on line or at the local parts store for what replacement brake items are available for the car that the master was used on. You did bench bleed the master first? On my 57 wagon I used 71 Chevelle brake parts, but I also have disc's on the front.

Here is a link to Bob's Impala brake items, worth a call to them.
http://www.impalas.com/brakes/

Here is a link to rock auto master cyl's
http://www.rockauto.com/catalog/raframecatalog.php

No not a mistake, if it was for Disc/ Drum set up??? it won't work on all Drums. I did this conv. on my 64 Catalina, & used a 68/70 A body [chevelle, Cutlass, Skylark etc] Dual M/cyl. "drum brake" application & didn't put a porportioning valve in & it works "just fine"!!!!! But as stated you do have to "Bench" bleed the master b-4 you install it on car then bleed the system.

RacerRick wrote:

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Also make sure you have the right ports going to the right brakes. If you have them reversed, the front brakes will be really week. Don't ask me how I know...

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 OK I won't ask, BUT have a very good guess?????

I think "maybe'the M/cyl. you have may be TOO BIG in the bore dia??? Did you get "good" pressure when bleeding front bleeders? Also was there a rubber boot on the back of M/cyl.where push rod goes into cyl. ??? My replacement M/cyl. had one & it restricted the stroke, & I "binned" the boot & got more stroke.

Chris,
The size of the lines don't hamper the pressure at all. Pressure in a closed hydraulic system is equal in all directions. They will have an impact on the volume of fluid delivered. I tend to agree with Dualquadpete that the master may in fact be too big. This is from Dean Oshiro a definite guru and all round good guy hotrodder. Take particular notice of the section regarding master cylinder piston size and pressure diferential. If you want to learn more about brakes go here and be overwhelmed

http://www.deanoshiro.com/brakes/master_cylinder_test.html

Formula for Master Cylinder Pressure

I have been asked hundreds of times how do you determine the pressures output of the master cylinder. The following information will help you determine the proper size master cylinder:

To figure how much pressure your master cylinder is putting out:
C = pedal ratio
D = pounds of pressure apply by your foot
E = area of you master cylinder
F = pounds of pressure out of the master cylinder
C X D /(divided by) E = F

Example: If you have a 1" master cylinder the area equals 1/2" x 1/2" x 3.14 = 0.785 Square Inches. So, 100 pounds (of applied foot pressure) X 6 (pedal ratio) divided by 0.785 = 764 pounds of pressure.
If you have a 1-1/8" master cylinder, 100 psi X 6 (pedal ratio) divided by 0.9935 = 604 pounds of pressure.

Here is some info on master cylinder with "constant" of 6 to 1 pedal ratio and 100 psi being applied.
3/4" master cylinder = 1359 psi
13/16" master cylinder = 1158 psi
7/8" master cylinder = 998 psi
15/16" master cylinder = 870 psi
1" master cylinder = 764 psi
1-1/8" master cylinder = 603 psi

DO NOT Try to use a OEM master cylinder smaller than 1" without calculating the volume requirement. It is like choosing between jump off a cliff or a plane, how do you want to die? Remember you can not do anything after you run out of brake fluid, but you can still press on the brake pedal harder.

-- Edited by Rochie on Tuesday 24th of April 2012 09:42:38 AM

Whew! Math this early? I'm at work right now so have to concentrate on making a living. I will try to digest all this later. Thanks man. Tell the boys at the ELTA howdy if you venture by there!

thanks l will check it out!

Chris...i went through the same thing on my 63 Nova and my 55 chevy..everything was new for the front braking system.listened to a half dozen mechanics and it kept costing me money by replacing lines, shoes etc.., yet nothing worked.....finally ordered a 68 camaro non power master cylinder put it on,threw the proportioning valve away ,"t"d of the front lines and bang, i had excellent brakes in both cars.....if by chance you doubt what dualquad and i are saying, just ask anyone who was at the arm drop drags how my car stopped after making a pass.... one thing i have learned over the years , when playing with these old cars, it's trial and error on most modifications..

yes it was Chris,,,wish i had the box with the part number for you but its long gone,,,

Here's the follow up to my issue...

I bought a dual reservoir master cylinder for a 68 Chevelle with NON-POWER 4 wheel DRUM brakes from Carquest. Bench bled it. Slapped it on. Bled the brakes. Done.

Now I stop like I should.

Thanks to all who gave their 2 cents and especially to Rochie to provided his wealth of experience while sittin in a lawn chair at the Plunkett Show earlier this month.

I think the master I was originally sold was either defective or for a disc/drum set-up.

Chris