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Discussion Starter #1
Before I put my engine back in I was going to repaint my MC but I think I want to replace it. I got it when I first got my car and before I found this forum. Its a 1" bore dual bowl for CJ's. I have 66 convertible 289 with front disk and rear drum. Proportioning valve and 10lb residual valve in line for the drums. I know I've read around here many times that I should have a 15/16" bore, correct? Also I know I've seen a few people post the correct one from Rock Auto. Can someone tell me again which one I need for my set up?

All I find on Rock Auto for a 66 is single bowl MC. So I'm sure I need to look for a different model year.

Couple of reasons I want to replace it:
1) don't think it's the right one
2) the pushrod has a clip but it doesn't click into the bore. Comes out very easily
3) there is some fluid getting by the bore. When I took the boot off, I found fluid there.
 

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This is the one I just put on my car. It has the 15/16" bore and internal residual valve. The only reason I ordered a Centrics is because I needed a few other things from Summit and I got free shipping. Otherwise I would have ordered the Raybestos one from Rockauto.

My old master cylinder had a 1"bore and no residual check valve. I haven't driven it yet so I can't comment on feel. It does have a little more travel which is to be expected.

 

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Discussion Starter #4
Raybestos 36440 works great with the 15/16" bore
Will this work with my residual valve already installed? It shouldnt matte if I already have one correct? Having two in line doesn't double the residual pressure, just unnecessary, right?
 

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Remove the existing external residual valve. Otherwise you'll have that much more hydraulic pressure drop on the system which will have some effect on the rear brakes
 

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Discussion Starter #6
@Huskinhano, how do I know if that Raybestos one has an internal residual valve?
 

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Will this work with my residual valve already installed? It shouldnt matte if I already have one correct? Having two in line doesn't double the residual pressure, just unnecessary, right?
The raybestos 36440 does not have a residual valve in it.
 

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If you are not sure if a master has a residual valve installed simply take a paper clip and if it slides in with no resistance in the outlet port you have no valve installed.
 

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Remove the existing external residual valve. Otherwise you'll have that much more hydraulic pressure drop on the system which will have some effect on the rear brakes
from the research I've done (whatever that's worth) I found Residual check valve to be non cumulative
Also FWIW I'm using an 87ish Crown Vic Aluminum master
one of our own is also using one of these
 
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