carb connections...vacuum booster connection

[Ken B]

I have 2 pics one shows the current connection for my new brake booster/master- I didnt install. The other pic is a quadrajet info sheet I found online.
I need someone who knows more than me to explain this to me. The way i see it the vacuum booster is connected to port G - bowl vent.....this seems wrong to me....again looking for an informed opinion I am just reading stuff and trying to deduce whats going on..
Thanks
Ken

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[xm20k]

There will ether be at fitting in the manifold behind the carb or in the rear of the carb baseplate.

 

[Ken B]

so that is incorrect and is there any harm done to booster?

 

[Ken B]

I know of the vacumn port at the back of the carb. I was looking for confirmation it was wrong

 

[legopnuematic]

What the booster is hooked up to now (bowl vent) has no vacuum to it, which is why you have no brake assist.

Move it to the rear port on the carb for full manifold vacuum and the bowl vent goes to a charcoal canister if you have one.

 

[Ken B]

thanks.....thiss incorrect connection doesnt have any effect on how the truck is running rough would it...if the vent cant vent?

 

[75gmck25]

What do you have connected to the brake booster port on the back of the baseplate?

The large threaded port on the back of the baseplate has full vacuum all the time. If it is not connected to the brake booster, or plugged completely, you will have a very big vacuum leak and the truck will run badly.

 

[straydog371]

Maybe these pics wil help?
First one is the back of the carb baseplate. Port is circled in red.
Second one is how mine is routed from the booster.

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[Ken B]

The port on the back of the carb is plugged.
Didn't have a booster b4..
I just need to find the fitting to adapt from threaded port to tubing.....what size and thread is that port if anyone knows.

 

[Ken B]

thanks for the replies and pics....i think I am in need of a 1/4 inch npt x 3/8 barb fitting...might try a 90 degree bend if it has enough clearance to rotate around....

 

[straydog371]

Mine is 3/8 OD steel line. I took another close up picture of the fittings.

LMC has some of the parts available if you decide to replicate the OEM setup:

https://www.lmctruck.com/mechanical/brakes/cc-1973-87-brake-master-cylinder-and-components

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[Ricko1966]

Okay so you were not power brake in the first place. You should relocate the brake pedal pushrod on your pedal or buy a pedal from a power brake equipped car. I think I put a link up already to a previous incident.

https://www.gmsquarebody.com/threads/squishy-brakes.44204/page-3

 

[Ken B]

thanks I have vacuum boost to the brakes!!!!

 

[bucket]

Okay so you were not power brake in the first place. You should relocate the brake pedal pushrod on your pedal or buy a pedal from a power brake equipped car. I think I put a link up already to a previous incident.

https://www.gmsquarebody.com/threads/squishy-brakes.44204/page-3

His replacement cab is a power brake cab though, so he doesn't need to worry about that.

 

[Sad Sack]

thanks for the replies and pics....i think I am in need of a 1/4 inch npt x 3/8 barb fitting...might try a 90 degree bend if it has enough clearance to rotate around....

And a booster filter.