Vacuum source for vacuum brake booster conversion

[86MCSS86]

I'm gathering all the parts to start the conversion on an 87 GN from power master brake booster to vacuum brake booster. I know they sell the conversion block but I would rather use my stock one if possible. I have one question where can I get the vacuum source for the brake booster? Which vacuum line can I tap into? Thanks

 

[Texas82GP]

I didn't know you could convert a boosted car to vacuum power breaks. Where will the vacuum come from? I realize when the throttle is closed you have manifold vacuum but is it enough? Otherwise, why weren't all of the cars just built with vacuum power brakes from the factory?

I realize this didn't answer your question but you made me curious. I hadn't heard of converting a turbo car to vacuum power brakes.

 

[lilbowtie]

I've got to agree w/ Tex if you are still a turbo car. When you let off on a turbo car the turbo takes time to spool down which there isn't any vac.
Either go w/ manual or you need another source - contact 565 on his set-up.

 

[UNGN]

'89 Turbo Trans Am's are Vacuum (that is where the proper block comes from)

Between my vacuum braked TTA and my hydroboosted T-type. I prefer the brake feel of hydroboost, but vacuum is much simpler/easier.

 

[565bbchevy]

I am running a pulley driven vacuum pump for my brakes, it is from a 95' Ford F350 diesel pickup truck and it self regulates itself at 28" of vacuum and does not require a vacuum source unlike the expensive electric vacuum pumps that require a vacuum source and only pull around 20" of vacuum.
I have been running this used one for over 15 years.
It's the black thing front driver's side.

 

[UNGN]

G-body parts has the machined Vacuum Block for only 45 dollars.

It's going to be hard to find a cheaper solution.

 

[TexasT]

Lots of guys drill and tap the manifold behind the doghouse and thread in a nipple for the hose to connect to. Be sure to use a check valve.

I'm with ungn on the hydroboost. Must be a Texas thang.
I don't think it any harder to install than the vac setup.
http://www.ihadav8.com/forum/index.php?topic=4228.0

 

[UNGN]

Rich,

Is the AL master cylinder a direct swap for the older cast Iron ones?

My dad put on the Iron one because he got a complete swap from an '84 GN. The AL on looks a lot more modern.

 

[TexasT]

I didn't like the look of the iron and I had read that the Cadillac one would bolt on. It went right on for me and has been on there for several years. Working great for me. The part number is in that thread I linked.

 

[86MCSS86]

The reason I'm converting the power master to vacuum is because the system needs to be changed out and power master systems tend to fail with no warnings. This is the second time the power master has failed the first time I almost got ran over. This time the brake light is on and no brakes so I'm done with power masters.

My brother has the hydroboost system on his diesel regal and I like it but the vacuum system seemed easier to install.

I looked at the link TexasT posted really nice to post pictures of all the part numbers used. If for some reason I don't like the vacuum system I will change it to hydroboost.

Thanks