# 68 disc brakes



## RRconductor76 (Nov 29, 2016)

Anyone have any pictures of how the brake line routing from the booster master cylinder, to the hold off valve, and to the distribution block of an original power disc brake 68 GTO. Thank you Allen


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## O52 (Jan 27, 2019)

From the net.


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## RRconductor76 (Nov 29, 2016)

Thank you O52 for the pictures,just what I needed.


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## BLK69JUDGE (Jun 10, 2010)

the red one is a hood tach hideaway car .....w manual trans
oh
and both are HO cars ... too ...by the heat riser shroud shape fairly sure

good pics !!


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## integrity6987 (May 10, 2017)

BLK69JUDGE said:


> ...by the heat riser shroud shape fairly sure
> 
> good pics !!


please explain


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## O52 (Jan 27, 2019)

Heat riser shrouds are different in appearance between the Std and RA/HO exhaust manifolds. 
The Std shroud has a metal tab on the right side where it mounts to the head.
RA/HO right side mounting hole is built into the shroud. 

And Scott is right on all counts. Heres a few more photos of the 'red' car.


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## Muttley (Jan 22, 2021)

O52 said:


> Heat riser shrouds are different in appearance between the Std and RA/HO exhaust manifolds.
> The Std shroud has a metal tab on the right side where it mounts to the head.
> RA/HO right side mounting hole is built into the shroud.
> 
> ...


In the second picture of this car, what is that fitting right beside the thermostat housing with the 3 lines (look like vacuum) attached to it ? I have that plug and this is the first time I've seen it actually attached. What are they and where do they go ?

I know this isn't related to the thread, but this is the first time I've seen them in.

Thanks!


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## O52 (Jan 27, 2019)

Thats your thermostatic vacuum switch. The 68 version had 5 lines attached to advance/retard the timing at idle depending on engine temperature. Normal position is to retard timing. If the engine was overheating (230*) the switch would open the advance vacuum line circuit to lower engine temperatures.
I believe the 69 had three. Not sure about the rest.


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## Muttley (Jan 22, 2021)

O52 said:


> Thats your thermostatic vacuum switch. The 68 version had 5 lines attached to advance/retard the timing at idle depending on engine temperature. Normal position is to retard timing. If the engine was overheating (230*) the switch would open the advance vacuum line circuit to lower engine temperatures.
> I believe the 69 had three. Not sure about the rest.


Not to further derail, but is that something that is required ? The 69 I'm working on has a 66 tri-power setup on it with no provision for that switch.


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## O52 (Jan 27, 2019)

No, unless your state or province is still doing smog inspections on these older cars.


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## Muttley (Jan 22, 2021)

O52 said:


> No, unless your state or province is still doing smog inspections on these older cars.


Excellent, no such thing here anymore ... especially on something that old. Thanks!


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