A little back ground. I have a very mild 350 set up. Only real changes are an edlebrock performer dual plane intake and a Holley 650 carb. The carb is set up spreadbore like my quadrajet. My brakes did not work very well (all new disks) so I went with a larger pipefitting on my intake to pull better vacuum. The problem is my carb hits this fitting. Currently the gasket between carb and intake has four holes (two large and two small to match the carb). I'm guessing my easier fix would be to place a spacer between my intake and carb. Will I be hurting myself any?
If not, What kind should I get? Do I need to keep the left and right seperate to match my dual plane intake?
Here is a picture of my set up before I changed the fitting.
http://s200.photobucket.com/albums/aa265/dauber65/?action=view&current=updated1.jpg

Will an intake spacer kill me?

If you eat it whole...

Do your brakes work well on the first application? Adding a larger fitting will have little effect except on successive applications where you have depleted the vacuum in the booster.

if you add a spacer you will add more low end and mid range torque. i dont think it will hurt anything.. but try it out and let us know. good luck.

Well if you take a good look at the brake line running to the booster you can see the issue. I have an extremely small line running to a T so I can bump it up to the booster size. This is because the only fitting I found that would fit under the carb has an extremely small (1/4) at most fitting. So I'm running a small hose from there up to a T then branching up to the proper hose size to the brakes. With the current set up I now have it is the exact same fitting on the booster as on the intake. The brakes do not work well at first. In fact they seem to only work good about halfway down. It feels like I've got no boost. The booster, master, dist block, lines and disks are all new and been bleed.
To back up my "lack of vacuum" example to my brake. I had the cowl T-ed into this line for awhile. It did not want to close the cowl at any time. I then hooked the cowl to a T I'm running from the carb to the trans and it slaps closed anything over idle.

Sounds like a 1inch open spacer would be about as good as I could get according to this article.

http://www.hotrod.com/techarticles/carburetor_spacers/

Anyone disagree?

if you add a spacer you will add more low end and mid range torque. i dont think it will hurt anything.. but try it out and let us know. good luck.
actually the opposite,
It will kill off a little low end & add some top end rpms.(think tunnel ram)

remember: the high the carb sits=the higher your rpm range;)


I'd figure out another way to fix the problem

oops got it backwards....

They do make 1/2" spacers also.

I'd figure out another way to fix the problem[/quote]

What is your recommendations? I looked into several fittings and I picked the one that got me the lowest profile. The only other thing I could think of is a custom made piece (much like the one that was on before, but had way to small of a port). My work shop is no more than two sets of wrenchs and socket set and a hammer. So my ability to go custum is limited.

I'd do a 1/2 inch if that would give me enough room. Its hard to estimate how much lift I would need without another set of hands and eyes.

isn't there a vacuum port ON the carb?
rear of the throttle plate?

If there is I need to look closer because that would make me a huge idiot.
I just put this carb on the car with amazing results. I wasn't too preoccupied by all the ports at the time.

My 70 convertible has a mild 350. At one time all I had was a Weiand intake that would not accept the holley I was using and I had to use a 1" spacer for adaptation purposes. Once I got rid of the spacer my low and mid range power had a notable power increase acknowledged by the seat of my pants..... and my fuel consumption decreased as well. On a mild engine like your I would try to not use the spacer.

Well everyone has scared me out of using a spacer for now. I'll try to tweak the fitting that was there originally and drill out the hole and try to get a bigger fitting in there and braze it closed or something. I can't beleive I couldn't find a low profile fitting anywhere. I went to Autozone and Advanced and all local hardware stores. I would have thought this was a common problem and there would be an easier solution than hand making something.

I don't think the problem is the fitting. If you don't have good brakes right from the first push, it isn't because the vacuum fitting is too small. You should have a good amount of vacuum stored in the booster regardless of the size of the manifold fitting.

What cam is in the motor? Where's the timing? (I don't mean, what does a "light" say on the "mark"; but rather, how far does it have to be advanced to make it start pinging?)

Why not just use the power brake port on the rear of the carb, and plug the port on the manifold?

I looked at my carb last night. I don't have a barb on the rear for vacuum (makes me feel better knowing I'm not crazy). All I have are two by the choke and one for PCV. One by choke is ported for dist. the other is rather small, but works fine for trans and cowl.
As far as I know I've got a stock cam. I've never advanced it enough to make it ping. I've got it set to around 35 degrees total advance currently.

Last night I made a homemade fitting by drilling out the side of a taller plug and brazing in a fuel line into the side. This should be low enough and non restrictive. I'll hook it up and see what happens. I hope it helps. I will let everyone know the results.

Should make everyone happy that I did not get a intake spacer.

By the way. This is the carb I'm running.
http://www.holley.com/data/TechService/Technical/4011%20Exploded%20View.pdf

Holleys never have had the rear power brake port. Q-jets have that.

Tom's wisdom never ceases to amaze me.:thumbsup:

Holleys never have had the rear power brake port. Q-jets have that.


I have 5 Holley carbs..........ALL have the brake vacuum port

By the way. This is the carb I'm running.
http://www.holley.com/data/TechService/Technical/4011%20Exploded%20View.pdf
there is a picture of the port on the baseplate

Tom's wisdom never ceases to amaze me.:thumbsup:

Normally his info is good, but this time
I can't agree with him.:noway:

Well maybe mine isn't 100% like that. Because I do not have that port. At first I thought that was the PVC, but then I relaized I was looking at it backwards.
Mine is a show carb that is all chrome. I did some decoding on it and found that to order a build I get the carbs parts that I posted. I'm not sure if it is exactly like that one. I had the carb off the car last night and there is definatly no port on the rear.

Holleys never have had the rear power brake port. Q-jets have that.

The holley 9895 650 spreadbore on my 1/2 ton sure has it, as does the older 600 and 750 vac sec holleys I have on the shelf, and the 3310 I installed on a 460 ford here a while back.

FWIW, there is no "nipple" for the power brake port on the rear of the carb. It is an internally threaded hole approx 1/2" in diameter on the baseplate itself. I am not familiar with the 4010/4011 series...maybe they don't have the power brake port, but I can't hardly imagine that as they are a street carb.

My 650 holley spread bore is the only holley I have purchased new, and it has a smaller than stock power brake port which required me to buy a brass adapter to mate it up to the stock power brake booster hardline. It came from the factory with a plug installed in the hole.

A few years ago I fixed a co-workers son's POS camaro that he had installed a brand new 4779 750 double pumper on (on top of a totally worn out engine :rolleyes: ). He had crudely adapted the factory power brake hardline to one of the vacuum ports on the intake manifold, and left the power brake port wide open on the back of the carb. He couldn't figure out why it wouldn't run right, or why he had practically no power brakes.

Travis,
Thanks for the info. I have been searching for a "nipple" *giggle to myself for a moment* the whole time. I wasn't looking for a plug that I could thread into. I'll give that a look. I may end up kicking myself by the time this is all over. I have already made my custom part, but it is nice to know when my custom elbow starts to have a vacuum leak.