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12-13-2012, 09:11 AM | #1 |
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Distributor Vac. Brake Line
Does anyone know the correct size of the Vacuum Brake line
that runs from the manifold to the distributor? The closest I can come to it is 3/16 which NAPA has, but the ID seems too small. Or does that matter. Ken |
12-13-2012, 09:23 AM | #2 |
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Re: Distributor Vac. Brake Line
Shouldn't matter.
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12-13-2012, 09:30 AM | #3 |
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Re: Distributor Vac. Brake Line
The one I have measures 3/16" (.187") od and 9/64" (.145") id. 3/16 brake tubing will work. It's only 1/64" smaller on the id. All the brake tubing I have is 1/8" id. You only need a vacuum signal for the distributor so 1/8" id is more than adequate.
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12-13-2012, 09:44 AM | #4 |
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Re: Distributor Vac. Brake Line
3/16" is corect size. Accualy on vacume lines smaller is better.ken ct. I have the correct fittings if you need them.
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12-13-2012, 10:38 AM | #5 |
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Re: Distributor Vac. Brake Line
Thanks for the replies. It looks like the suppy at NAPA
will do the job. KenCT, Thanks but I have the fittings. I just need a longer line to accomodate the vac. position on a blower manifold I'm working on. Ken |
12-13-2012, 11:26 AM | #6 |
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Re: Distributor Vac. Brake Line
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12-13-2012, 11:30 AM | #7 | |
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Re: Distributor Vac. Brake Line
Quote:
I like that idea , a vacuum line on a blown engine to the distributor brake. Vac = no retard and boost would push the piston in applying some retard to the advance .... |
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12-13-2012, 02:19 PM | #8 |
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Re: Distributor Vac. Brake Line
Hey Jim, Thanks for the post. Now, I'm easily confused so I have to ask.
Are you implying that it really is a good idea or no. The blower is a 39M McCulloch and it does have the vac. port provided as an original manifold to supply vacuum to the distributor (Helmet type). It will be used on an otherwise stock '39 221" motor just as McCulloch did back in the day. Ken |
12-13-2012, 02:46 PM | #9 |
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Re: Distributor Vac. Brake Line
I'm actually running one of your Crabs also Jim and I have a McCulloch supercharger on my engine (I told you about it when I ordered the crab.)
It didn't run so hot when I put it on , so I backed the vacuum brake nut off a LOT and it runs way better. I'm pulling the vacuum line off the front vacuum port on a stock 1936 aluminum intake. I tested it with thumb power revving the engine and there is vacuum all the time at that point, decreasing as the rpms rise, but never blowing my thumb off the port. always sucking. Anything I'm doing wrong?
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12-13-2012, 03:35 PM | #10 |
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Re: Distributor Vac. Brake Line
Have you ever tried running the vac off the bottom of the carb. That's where we're using it on an Eaton blower. Unfortunately we don't have it running yet.
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12-13-2012, 04:56 PM | #11 |
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Re: Distributor Vac. Brake Line
The manifold air pressure above the blower and below the blower are bound to be different even if the blower doesn't put out much pressure. The vacuum brake is designed to work on a more normal manifold pressure and I think the closest thing to that would be between the carb throttle plates and the blower inlet but I don't know how it would compare to an unblown engine's M.A.P. There is low pressure due to engine draw and compressor draw too. I don't know what the compressor inlet pressure variation would compare to unless a person compared MAP gauge readings between a blown engine and an unblown engine to check it out.
The other option would be to go with mechanical advance only. It won't be as good on the gas but it will work to keep the timing somewhere near a decent specification. Last edited by rotorwrench; 12-13-2012 at 05:07 PM. |
12-13-2012, 05:03 PM | #12 |
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Re: Distributor Vac. Brake Line
Vacume from the rear port of a later 94 carb is much less than manifold vac. Look at the size of the hole in the left side ventury its about the size of a smaller paper clip. ken ct.
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12-13-2012, 05:12 PM | #13 |
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Re: Distributor Vac. Brake Line
Ron and Rotorwrench make a good point. That's probably what Bubba was pointing out. I've got a vacuum plate that should work. KenCt. thanks for the info on the flared fittings. That is what I have. Ken
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12-13-2012, 09:24 PM | #14 |
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Re: Distributor Vac. Brake Line
Flare fittings will not work in the vacume port holes in the intake or rear of carb.These are unique fittings on ford carbs and intake. ken ct.
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