Master cylinder vacuum

[Gunstar1]

I have a 77 Firebird that we've yanked the 305 (yuck) and are preparing to put in a Pontiac 400. With the old engine, the vacuum line from the master cylinder was hooked to the backside of the baseplate on the 2BBL carb.

However, with the 4BBL Rochester Q-Jet I plan to use, there is no connection at the back of the baseplate to hook into. There is a vacuum port on the manifold that the line from the lifter pan is hooked into. Would this vacuum port provide enough vacuum to properly operate the master cylinder?

Or...

Would it be possible to drill and tap a hole with a fitting into the back of the baseplate on the carb to do this?

[volkerc]

Originally Posted by Gunstar1

I have a 77 Firebird that we've yanked the 305 (yuck) and are preparing to put in a Pontiac 400. With the old engine, the vacuum line from the master cylinder was hooked to the backside of the baseplate on the 2BBL carb.

However, with the 4BBL Rochester Q-Jet I plan to use, there is no connection at the back of the baseplate to hook into. There is a vacuum port on the manifold that the line from the lifter pan is hooked into. Would this vacuum port provide enough vacuum to properly operate the master cylinder?

Or...

Would it be possible to drill and tap a hole with a fitting into the back of the baseplate on the carb to do this?

First off, you are talking about the vacuum line for the brake booster.
Secondly, congratulations on pulling the 305! The vacuum line to the valley pan is for the pcv valve. All you need to do is hook up vacuum to your manifold. I'm sure there are a few blind screws that are screwed into your manifold, take one out and replace it with a hookup for a line.

[Gunstar1]

Originally Posted by volkerc

First off, you are talking about the vacuum line for the brake booster.
Secondly, congratulations on pulling the 305! The vacuum line to the valley pan is for the pcv valve. All you need to do is hook up vacuum to your manifold. I'm sure there are a few blind screws that are screwed into your manifold, take one out and replace it with a hookup for a line.

Ah, brake booster, thanks for straightining me out on that one.

Yeah, the 305 ran good, but very weak in the power department. Although I was surprised to get a 17.04 @ 81 out of it. That's with just a 2BBL carb, too.

I see a few allen wrench plugs in the manifold that might just work.

Thanks for your help! I want to make the car go, but I also need to stop.

[volkerc]

Originally Posted by Gunstar1

Ah, brake booster, thanks for straightining me out on that one.

Yeah, the 305 ran good, but very weak in the power department. Although I was surprised to get a 17.04 @ 81 out of it. That's with just a 2BBL carb, too.

I see a few allen wrench plugs in the manifold that might just work.

Thanks for your help! I want to make the car go, but I also need to stop.

runs good, needs brakes, i hear you. those allen wrench plugs are the ones to take out, i wish i could post a pic of my engine and you would see the routing, unfortunately i have no idea how to get a pic in here...

[FormulaLT1]

If you would like me to host a pic for you just email it to me and I will put it in your post for you. or host it yourself on www.imageshack.us and use the [img]url[/img] format link they give you to post your image on here. These are directions I had wrote on posting a pic http://www.automotiveforums.com/vbul...&postcount=139.

John
here my email if you need me to host it for you [email protected]

[volkerc]

well, you were supposed to see a picture with the area of interest circled in red, not sure if you can see it, if not here is the link:

http://img86.exs.cx/my.php?loc=img86...dintake7xy.png

thanks for your info LT1!