671 wieand intake has no vacuum port?

I just bought a set of 80575 holley boost referenced carbs...they have two outlets on each carb. I was told they need to be referenced below the blower. The 671 blower intake does not have an vacuum fittings?

Can some one send me a pic of where I should drill a fitting on the blower manifold?

 

can you post a pic of your intake? My guess is you just need to find somewhere that it's not too thick, that won't be in the way of anything else, etc. Probably on the back of the manifold, into the plenum. That's where the hole is on my BDS intake. btw how are you supposed to connect a boost gage with no hole?

 

Can it be drilled into the same chamber as the pop-off valve?

 

yes

 

I have drilled my hole in to the intake down of where the carb sits. The hole is tapped 1/8 bspt.

 

I know what you mean, gotta tear this mess apart to do the same thing.

 

If memory serves me correctly,,,all blower intakes don't have a vacuum port,,that is because anything under the blower is Under Boost.
It would destroy anything that operates on vacuum.
I guess they didn't put a port to keep someone from ruining there accessories. I guess for a boost gauge you just find a good spot and drill and tap?

What is a boost referenced carb,,never heard of it?
Call Holley,,they should have some diagram of where you need to drill.
Good luck.

Tommy

 

A boost referenced carb has the vacuum side of the power valve connected to an external port, instead of to the base plate. The idea is that you can connect it to wherever you want...if you run a blower, you can connect it below the blower, so it will get a more accurate indication of engine load.

 

So the power valves work off of boost instead of vacuum?

Sounds like a good idea to keep from blowing valves like use to happen from a backfire.

Tommy

 

They see both. Also, I'm not saying they are indestructible, but Holley power valves are probably a lot tougher than most people think.

 

And when you find the "sweet spot",use #3 or #4 hardlines with a "t",that way you can reference the carbs and a boost gauge at the same time.

 

Do you know what the history on those carbs were. I've always used Holley made PV's and I can't say I have ever had one go bad on my personal cars.

 

I drilled into the #8 runner... 1/8 NPT. Worked well. Routed lines to the carbs. I have fuel pressure issues now but will adjust the regulator, as the motor will only run when I manually prime the motor.

Some of you were interested in the boost refence, they are Holley 4150 HP #80575 blower carbs.