Is this a vacuum port?

I'm ***uming this is a pinched off vacuum port on my Rochester 2 barrel....but just want to double check before I open it up to hook a line to...it's right under the serial numbers on the float bowl.



Here's bonus motor pic for ya....


HEY....while I'm at it. The new manifold doesn't have a mount for the alternator bracket. I'm figuring just re-fab the bottom of the mount to bolt to the first intake manifold bolt?

 

Yes that's a vac port but only good for the vac*** advance as the port is above the throttle plates>>>>.

 

It looks like that tube is a vacuum port but I'm not 100% sure. What type of vacuum are you looking for (ported or manifold)? It looks pretty high so it may be ported.

The alternator bracket....sounds like you have the same idea I would. I might use some loc***e on the bolt just to me safe. Sorry that's the aircraft mech coming out of me.

 

I just need it for the vacuum advance on the dist.
There's another port that's drilled into the manifold on the other side that I planned to use for the vacuum modulator on the powerglide.

 

That's ported vacuum....will be fine for your vacuum advance.

 

looks like your center carb? Wonder why it was pinched off rather than just capped? ******....

wonder if you could get on it sideways with a little channel lock & give a squeeze, re-open it? Pretty sure if you want to run vac advance that's your boy right there on the primary carb. Are the outboard carbs squeezed off too or just capped?

looks like that center carb isn't fastened to it's base?

 

caps are like... $.75... why not just pinch it off

 

It's even folded over itself.
I'll just cut the end off with my Dremel, there'll still be enough left for the vacuum line.

 

Those brackets usually mount to the cylinder head, I think.

Consider using a bolt with a stud on top instead of a regular bolt if you modify the alt. bracket. That way you don't have to worry about it coming loose.

 

I think the heads are 283 and did not have accessory holes in them. It was all done off the cast intake.

 

I know its not traditional but look at the allen grove mounts.. Nice **** . Mounts the alternator over the valve cover and they really work well .
Dave

 

It's more than likely ported vacuum.

Using that for the vacuum advance may lead to overheating.

Use manifold vacuum instead.

 

That is the port that GM used for the vacuum advance on that year Rochester but it is NOT ported vacuum. It goes in and makes a 90 deg turn straight down through the cast iron base and comes out well below the throttle plates. That port has vacuum all the time. Just because it enters the carb above the plates doesn't mean that it isn't routed below the plates internally.

The threads are 1/8" NPT. You can get a male adapter for hard line or a male hose ******. Some year Rochester's have a tube at that spot for the advance that used a hose instead of the hard line.

GM used straight vacuum for their vacuum advance distributors despite where it enters the body of the carb.

Here is some good reading on the ported vacuum myth by a GM engineer.

 

I thought I had a vacuum port once, but then I found out that it just really ****ED!


Thangyou,....Thangyouverymuch.

 

The early V8 had generators that were smaller diameter than the alternators. The long end of the adjuster bracket was bolted to the water pump top bolt IIRC. The alternator is larger in diameter and the adjusting bolt in higher so the original bracket is too short. If you make a bracket to use the original arm you might want to consider having it bolt to the water pump and the manifold. It will be a lot stronger and won't try to pivot on the single attaching bolt.

Joe