327-210hp distributor vacuum source - Team Camaro Tech
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post #1 of 8 (permalink) Old Apr 10th, 08, 08:19 PM Thread Starter
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327-210hp distributor vacuum source

Is the vacuum source on the stock 2 barrel carb a timed port or full vaccum?

Murph
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post #2 of 8 (permalink) Old Apr 10th, 08, 08:22 PM
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Re: 327-210hp distributor vacuum source

I think all the cars were port vacuum for emissions.

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post #3 of 8 (permalink) Old Apr 16th, 08, 07:52 PM Thread Starter
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Re: 327-210hp distributor vacuum source

So is it safe to say that since the disrtibutor vacuum line connected to the carb (2GV) up near the fuel inlet that it used port vacuum? I think i have read that if the vacuum tap is below the throttle plate then it is manifold and if it is above the throttle plate then it is ported vacuum.
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post #4 of 8 (permalink) Old Apr 16th, 08, 10:04 PM
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Re: 327-210hp distributor vacuum source

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Originally Posted by murph's 68 View Post
So is it safe to say that since the disrtibutor vacuum line connected to the carb (2GV) up near the fuel inlet that it used port vacuum? I think i have read that if the vacuum tap is below the throttle plate then it is manifold and if it is above the throttle plate then it is ported vacuum.
Demon carbs have both "taps" below the throttle blades or more at the same level. One goes to a ported source well above and into the venturi. The other feeds through channels to the underside of the carb to expose the manifold vacuum.

It is easy to tell which is which. Ported will not show vacuum at idle. Manifold will.

If you are trying to figure the rate your vacuum can runs at just hook a handheld vacuum pump straight to the vacuum can. Let the engine idle and check the timing. Then, slowly increase vacuum with the handheld pump and plot the curve of the can using the timing light.

Nobody should need to take their distributor to a shop to have it dialed. There is no magic in a distributor, it is a simple device. You need a timing light, a handheld vacuum pump if you have (vac. advance), an advance curve kit, and a tach. Just plot your curve every couple inches of vacuum for the vacuum advance. Plot your mechanical advance curve above idle based on RPM and degrees. From there it is just a matter of making sure the internal parts are working right. Make sure nothing is sticking and that the weights are swinging out all the way and returning (this will show up on your plotted advance curves).

I like a lot of initial advance. I run 20o with 14o mechanical and @16o ported vacuum, all in by 2,500 to 3,000. I like the curve to start a few hundred RPM above idle. Make sure you don't use up any of your mechanical advance at idle. Depending on how close you are, you may be into your curve in park, but make sure you are not in drive.
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post #5 of 8 (permalink) Old Apr 17th, 08, 04:47 AM
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Re: 327-210hp distributor vacuum source

Quote:
Originally Posted by murph's 68 View Post
So is it safe to say that since the disrtibutor vacuum line connected to the carb (2GV) up near the fuel inlet that it used port vacuum? I think i have read that if the vacuum tap is below the throttle plate then it is manifold and if it is above the throttle plate then it is ported vacuum.
You are right in definition.

Measure both at idle rpm. The one with vacuum is full time from the manifold. The other nipple is ported with no vacuum at idle.

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post #6 of 8 (permalink) Old Apr 17th, 08, 06:20 PM Thread Starter
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Re: 327-210hp distributor vacuum source

OK. The problem is the carb is no longer on the engine. Here's the short story. 2 brl leaking gas. I'll rebuild. Hit carb studs with liquid wrench for like 2 weeks. Try to remove carb for rebuild and snap 1 front stud. All others nuts come off. The other front stud is real thin, try removing it and snap it. This is getting to be too much work. Maybe I should just put a 4 brl manifold and carb on it. OK I'll do that. Better yet, I have a new set of vortec heads in the garage so let's put them on also. So the first thing on the new carb instructions say to check the vacuum source for current carb by disconnecting similar to what you describe. Since the current carb is off I have no way to tell which source it was hooked up to only the location on the 2 brl. This is my dilema. Trying to determine which vacuum source to hook the distributor up to on the new carb.

And by the way, it spiraled a little more out of control and I will be ordering a 200-R4 next week to replace the powerglide

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post #7 of 8 (permalink) Old Apr 17th, 08, 06:35 PM
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Re: 327-210hp distributor vacuum source

LOL....

(in a Fred Flintstone voice...)
and awaaay we go!
lol. It was a leaky carb. Now its a 4brl, alum intake, and vortec heads with a 200-4r. Very nice combo. should make some fun power.

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post #8 of 8 (permalink) Old Apr 17th, 08, 06:54 PM
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Re: 327-210hp distributor vacuum source

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Originally Posted by murph's 68 View Post
OK. The problem is the carb is no longer on the engine. Here's the short story. 2 brl leaking gas. I'll rebuild. Hit carb studs with liquid wrench for like 2 weeks. Try to remove carb for rebuild and snap 1 front stud. All others nuts come off. The other front stud is real thin, try removing it and snap it. This is getting to be too much work. Maybe I should just put a 4 brl manifold and carb on it. OK I'll do that. Better yet, I have a new set of vortec heads in the garage so let's put them on also. So the first thing on the new carb instructions say to check the vacuum source for current carb by disconnecting similar to what you describe. Since the current carb is off I have no way to tell which source it was hooked up to only the location on the 2 brl. This is my dilema. Trying to determine which vacuum source to hook the distributor up to on the new carb.

And by the way, it spiraled a little more out of control and I will be ordering a 200-R4 next week to replace the powerglide

Murph
It is possible to get better mileage out of a 4 barrel. Especially with fine tuning i.e. IFRs, IABs, MABs, jets, PVCRs. The benefit will come if you run say a 600 CFM vacuum sec. actuated four barrel like the 1850. A 4 barrel intake can help distribute fuel better to all the cylinders. You can run a 4 barrel intake and if you for some reason want a 2 barrel carb again you can get an adapter and bolt it on. You can even mess with forward rear placement of the 2 barrel carb. A 4 barrel carb on a 2 barrel intake is not good.

If you are having trouble getting the studs out of the 2 barrel intake get some easy outs. Or just drill them completely out and retap or thread repair.
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