Identify broken part

[jtrapani]

I replaced my intake manifold last night and pulled a "T" shaped part out of the old intake. It sits just behind the carb and has two hoses coming out of the "T". Its a threaded part. What is it, can I block it off, and any idea how much it costs???? (I broke one of the nipples that hold the hoses)

Thanks.

 

[84zz4ss]

Sounds like a vacuum T. You can plug the hole but the accessory needing vacuum will not get any.

More info?

 

[dremu]

I replaced my intake manifold last night and pulled a "T" shaped part out of the old intake. It sits just behind the carb and has two hoses coming out of the "T". Its a threaded part. What is it, can I block it off, and any idea how much it costs???? (I broke one of the nipples that hold the hoses)

Thanks.

Threaded, or *barbed*? Should be barbed.

If it's plastic, like I think it is, as mentioned that's your basic vacuum tee. Any decent parts house should have 'em, coupla bucks. Even the crappy ones will have a mixed pack in the Motormite "Help!" section, oughta find one the right size.

-- A

 

[jtrapani]

its not plastic. and its threaded. directly behind the carb. it's about a half inch tap into the intake.

 

[dremu]

its not plastic. and its threaded. directly behind the carb. it's about a half inch tap into the intake.

Oh, it's a vacuum switch. There are different flavors; I thought LMC had 'em but I can't find in the online catalog right off. The dealer oughta have, but spendy. Gimme a couple of minutes.

-- A

 

[4X4HIGH]

Sounds like a vacuum fitting that probably has power brakes to the large fitting and a smaller fitting which would go to an automatic trans modulator valve assuming it is a TH350 or TH400 transmission. The fitting is usually made of a pot metal and threads into the intake manifold just behind the carb and then the hose fittings are barbed to hold the vacuum hose on.

 

[dremu]

Kragen/Schucks/Checker/O'Reilly lists them as "ported vacuum switch"; apparently they're differentiated by color. (White, blue, etc, must be different vacuum pressure to open/close 'em.)

Well, and obviously the number of ports =))

Anyway, looks like ~$23 is the average price there.

-- A

 

[4X4HIGH]

Oh, it's a vacuum switch. There are different flavors; I thought LMC had 'em but I can't find in the online catalog right off. The dealer oughta have, but spendy. Gimme a couple of minutes.

-- A

Aaron, i think you're thinking about a thermal vacuum switch but those are at the front of the manifold and thread into a water passage and the fitting is both metal and plastic.

 

[jtrapani]

you guys are awesome. Thanks

 

[4X4HIGH]

So is it a thermal vacuum switch or a vacuum fitting? My guess is just a plain old vacuum fitting from your description of its location.

 

[dremu]

So is it a thermal vacuum switch or a vacuum fitting? My guess is just a plain old vacuum fitting from your description of its location.

Huh ... so it's a vacuum tee, but threaded in?

-- A

 

[4X4HIGH]

Huh ... so it's a vacuum tee, but threaded in?

-- A

Yes, carbed engines used a metal thread in vacuum tee behind the carb in an intake runner for power brake booster and also transmission modulator valve.

 

[dremu]

Yeah, I remember the port at the back of the carb, for the vacuum booster, but I remember it having a pipe nipple and rubber hose. Huh.

-- A

 

[4X4HIGH]

Yeah, I remember the port at the back of the carb, for the vacuum booster, but I remember it having a pipe nipple and rubber hose. Huh.

-- A

Brake booster goes to manifold vacuum via a fitting in the intake runner. Some people have been known to use the large vacuum fitting on the rear of the carb (this is still manifold vacuum) but they weren't hooked to the carb from the factory.