Is the vacuum port 1/2"?
And I wanted an open plenum. My current one is like yours.

 

Good question, I can't remember the size, but it is the same size as the pcv valve.

Going to bed now, but can check tomorrow if you want.

Mine has grooves in the bores coz apparently it improves torque.

I forgot that you'd made a comment about open versus 4 hole spacers.

I remember reading about the differences, but can't remember them either.

 

It’s possible that the comparisons have been made, but the only ones I’ve ever seen were all involving throttle-body fuel injection systems.
I’ve never seen a back to back test of open versus individual bores done with carburetors.

With TBI at least, the open bores had a slight advantage over the individuals. Better idle and off-idle throttle response were some of the benefits I believe.

 

I just match the intake. In my head, it makes more sense. My question is, is there more vacuum at the spacer or from an intake port?

 

I would use a 90 degree threaded fitting and then have a coupling to that. The last thing you want is vacuum leaks.

 

Just curious why you guys don't just run the PCV to the port on your carburetors?

 

For me, my Holley is old enough (014 date code = likely Jan 04, 1970) that it has no PCV port. Besides, I don't like oil vapors sucked in right at the edge of the throttle plates in the base plate ... using a spacer below with shared space gets any oil vapor a little bit away, but still central to the whole intake ... just seems cleaner somehow.

 

Because it is too small. I need a 1/2" port.
That's where it is now and there's not enough flow.

 

Paul, these pictures were taken in Aug 2020 just up the road from me.
The gentleman on the left is my good friend Geof, that's who I bought my truck from.

Brad Lovell called him and said they were on their way from doing the Rubicon Trail to Moab
and didn't want to stop in Richfield for dinner and draw a crowd to see the "new" Broncos so
he asked Geof and his wife if they would feed them. These guys did the majority of the R&D for the new Bronco.

Those three Broncos were 3 years old at the time the picture was taken.


Geof has worked on Brad's pit crew and Fire Guy's Racing out of Colorado.

The open plenum space makes sense to me, does it really help??
Who knows.

 

There's just one port on the intake and its way too small.

 

The vacuum port is 0.44'', so that's basically 1/2''.

The PCV valve is also 0.44''.

Go ahead and fit the UBK spacer once you're finished, and try it out.

Then fit the 4 hole spacer and try that out.

I doubt you'll feel any difference, but it will/should satisfy any and all curiosities.

If I remember correctly, the 4 hole spacer favors torque, and the 1 hole spacer favors HP.

 

I've never checked the vacuum with a gauge at the spacer fitting, but I would expect to see no difference between that and an intake port.

 

I like the pcv pipe to be at the rear and out of sight, as opposed to being connected to the front port on a carb.

I use the rear carb port for the brake booster, and don't really like seeing a connection to the intake.

Purely esthetic.

 

Here's the spacer I took off. Not much f a vacuum source.


Here's the new set up, way more flow.

The new problem?? A flat washer made it into one of the cylinders.
Its getting old, really old.

 

that's what I was referring to is the typical large port on the back of holleys and edelbrock has a provision for it as well, I believe it's a 3/8". After I said that I remembered I do have my brake booster going to my carb and my PCV is going to that fitting on the #4 intake runner, which I don't necessarily like either. Now I'm thinking I may get a T fitting and put both my PCV and booster to the carb. I get the idea of what they're doing with the spacers as opposed to using one intake runner for all of your vacuum source. I could see it causing a lean condition for that cylinder. I'm kind of confused at wanting more air through a PCV valve though.