The Stovebolt Site Forums The Shop Area Engine Shop Where to hook up vacuum gauge for idle mixture??

So where do you hook up the vacuum gauge for idle mixture. Do you remove the vacuum line that goes to the distributor and hook it up there? Aren't you supposed to have the distributor hooked up when adjusting idle mixture. My truck is a 1959 with a stock 235 and auto-choke Rochestor. I have done the normal idle adjustment by turning the screw in till it stumbles and then turning it back out till maximum RPM is achieved. I just want to learn how to adjust the idle/distributor advance the " vacuum gauge " way. I do have a slight stumble when hit the gas from idle. Thanks for your time

There should be a port on the side of the intake manifold. This port was used by the vacuum wiper, but might be plugged if you have electric wipers.

There is a port on the side of the Intake manifold, but I have electric wipers and it is blocked like you said.. So now what? Thanks

You can get a nipple to thread into that hole & hook a hose to your gauge. Anything below the throttle plate is manifold vacuum, that's what you want to be checking for tuning & driving economy. The only vacuum port on the 'B' is above the throttle for the vacuum advance, will have little or no vacuume at idle & increase as you come off idle.

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Remove the plug, my gauge came with a barbed adapter
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You the MAN DADS50!!!! Those pics tell the hole story. I'm not home right now, but I'll check to see if that barbed adapter came with my kit; looks like we might have both bought the same kit.

So it looks like my kit did not come with that adapter. Any idea where I can get one of these??

Take the plug to NAPA/etc and see if thy have a nipple that fits the hole and your tube (as suggested by BC59).

Check your local auto parts store in the Dorman bins

You could also use a pipe nipple as suggested above,
I believe mine is 1/8 pipe, but your 235 being a different year it could be bigger

I actually was able to pick one up at my local Ace Hardware. Thanks for the tips

What to do if that side plug is frozen? Do you think I could take a large pipe wrench to it? Would if be better and safer to drill and tap another hole in the manifold?

Depending on what you are calling 'frozen,' I would not take a large pipe wrench to that plug. But, if it is just 'stuck-in-there/been-there-awhile' frozen I would get it out as opposed to drilling another hole. Spray it down with penetrant (blaster, Kroil, et cetera) and let it sit for a while (period of time long enough for the oil to work).

Get the appropriate-sized wrench on the plug, turn a degree or two to tighten the plug first, & then see if it will back on out.

Brad

Heat is your friend- - - -Use a Propane or Acetyline torch, get the plug hot (almost red), and apply a block of paraffin or a candle to the threads. The wax and heat method works much better than penetrating oil to free up a stuck thread.
Jerry

That plug is a tapered thread. Do what HRL recommends. If it still doesn't come out, hit the end of the plug with a number of sharp blows with a Medium Danged Hammer (BFH s overkill for this application). Being tapered, hammer blows have a tendency of causing the tapered threads to come apart. I don't understand why this is so, and I don't care if it turns out to be magic. It has worked for me.
Carl

This morning I drove my 48 Chev to a muffler shop with the idea to ask them to weld an old lug nut to the frozen plug now that the corners were rounded off. Welder was afraid to weld so near to the carb. He thought he could wrench the plug off with a pair of vise grips. No luck he was determined and wacked the plug with a hammer, nothing. Then he tried using a chisel and hammer to turn the plug nothing. Finally he broke the plug flush with the manifold leaving the threads and a hollow center. I drove home and used an easy-out to no avail. The plug was apparently made of lead because the easy out just bored into it.
Next I used a jig saw with an abrasion blade and cut into the treads at several different places. Worried about the dust and shaving I decided to use a pencil magnet to fish out any bits that may have fallen inside the manifold. Not satisfied with that I removed the carburetor and cleaned out the manifold via the opening. I also used a small vacuum to suck up any foreign bits. The left over threads came away once I cut into them.
From ACE hardware I bought the needed fittings to make a manifold vacuum port. Tomorrow I will try to adjust the carb fuel mixture using a vacuum gauge.
Thanks for all the hints and advice.