brake booster vacuumm question

[87chevy.com]

Is there any specific location for the port on the intake manifold for a vacuum source for the vacuum assist brake booster? Most common is in the rear most likely to reduce the cost of hose to connect the two.
But does it matter where in the manifold as long as its after the throttle body blade and in the main section of intake, ie, not in an intake runner?
I don't have a gen3 manifold to see if the brake booster port just "taps into" the "reservoir of vacuum" aka intake manifold of there's some nonsense around it. I know its not centered and could also be that away to save on the cost of hose??

Thanks,
clint

[68gmsee]

I'm pretty sure the vacuum hose to the booster location is more of a convenience and intrusiveness factor than cost factor. A few inches of vacuum hose would cost pennies and wouldn't make a dent on the cost of the car. But to answer your question, any full manifold vacuum source will do as you mentioned. Just need to find the most convenient, least intrusive location on the manifold that works for you.

[James the III]

Originally Posted by 68gmsee

I'm pretty sure the vacuum hose to the booster location is more of a convenience and intrusiveness factor than cost factor. A few inches of vacuum hose would cost pennies and wouldn't make a dent on the cost of the car. But to answer your question, any full manifold vacuum source will do as you mentioned. Just need to find the most convenient, least intrusive location on the manifold that works for you.

When building vehicles pennies= millions so cost is #1.
Machining and tapping an iron intake cost tons more than drilling alum base plate and a pressed in barb.

And yes any place in the intake ports is fine.. just make sure the one way check valve is in the line between the booster and intake..
if fuel vapor gets to the booster diaphragm it can kill it in short order.. With ethanol mixed fuel it's cheap insurance to install a new one..

[68gmsee]

Originally Posted by James the III

When building vehicles pennies= millions so cost is #1....

Sure, I understand that pennies leads to overall cost when manufacturing by the hundreds of thousands, just so happens that behind the carb is the most convenient place and shortest also.

On that same note, I always wondered why they changed the location of the A/C compressor on square body trucks to the drivers side. Never did like the hoses routed across the front of the engine.

[Wrenchbender Ret]

A full manifold vacuum source is correct but it must be a 3/8 tube outlet.

[storm9c1]

Yep, use a larger (3/8" minimum) nipple. Doesn't matter if it's in the intake or carb. And it doesn't have to be exactly centered in the intake, but it also shouldn't be too far into a runner as you mentioned. I do recommend using a dedicated port. I don't recommend sharing the same source with another vacuum accessory (ie: using a tree/tee/manifold) so you have full vacuum to the booster at all times for safety.

[87chevy.com]

Sound about right. I'm going to pull the trigger and mod the intake and fitting. It's for the LT 5.3... it will be months before I get to test it though.. waiting on Holley to quit changing the pre order ship date!
Thanks for the input
Clint

[sprint_9]

The port dumps right into the main intake cavity, atleast it did on my gen 4 5.3.

Are you planning on cutting the quick connect port off of a donor intake and welding it onto your gen 5?

Atleast Im not the only one dealing with Holley's ship dates.....

[87chevy.com]

Originally Posted by sprint_9

The port dumps right into the main intake cavity, atleast it did on my gen 4 5.3.

Are you planning on cutting the quick connect port off of a donor intake and welding it onto your gen 5?

Atleast Im not the only one dealing with Holley's ship dates.....

Not going to drill a new hole, just use the purge valve port. Drill it the same size all the way through, and turn down the vacuum pump brass fitting threads off and press it in there... maybe put a few grooves on it and fill the grooves with rtv. Then include use the brake booster line and fittings... that's the plan atleast.

Clint