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455 Rebuild Questions - Intake manifold connections

Old June 2nd, 2008, 05:57 PM
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455 Rebuild Questions - Intake manifold connections

Two questions:
1. Can anyone tell me what this piece is called and describe what it's function is? (pic below)

2. How do most people handle the heater control valve situation with a 455
in a Cutlass. The one that came with my rebuilt motor is obviously vacuum controlled (I'm assuming the vacuum hose went to the thermostat controls in the dashboard - Olds 98.) Should my Cutlass have the same vacuum hose connection under the dash?

Sorry it these questions are trivial. Obviously, I'm fumbling through these issues one at a time. Thanks in advance. I greatly appreciate your help.
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Old June 2nd, 2008, 06:45 PM
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It's a ported vacuum switch. There will be a MT on the bottom port. That goes to the intake vac. port. The middle port should have a C on it. That goes to the Carb. vac. port. The top port should have D on it. And that goes to the Distributor Vac advance.
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Old June 2nd, 2008, 06:49 PM
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Excellent - Thanks a lot.
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Old June 2nd, 2008, 07:21 PM
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Originally Posted by esisson View Post
Two questions:
1. Can anyone tell me what this piece is called and describe what it's function is? (pic below)
The purpose of the valve is to provide full manifold vacuum to the vac advance if the engine starts to overheat. This was an early attempt to reduce NOX emissions by inhibiting vac advance in lower gears. The problem was that the retarded timing could lead to overheating in stop and go traffic, so the thermal valve would open to provide full vac advance under hot conditions.

2. How do most people handle the heater control valve situation with a 455
in a Cutlass. The one that came with my rebuilt motor is obviously vacuum controlled (I'm assuming the vacuum hose went to the thermostat controls in the dashboard - Olds 98.) Should my Cutlass have the same vacuum hose connection under the dash?
If the A-body has A/C, it will have the vac connection for the heater valve. If the car does not have A/C, there was no valve used. Just remove the vac-controlled valve and replace it with a straight nipple.
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Old June 3rd, 2008, 03:15 AM
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Thanks Joe. My car has no A/C. I'm having trouble finding a straight through connection to replace the Vac controlled valve. I'm hesitant to go into Autozone and ask for a straight nipple. LOL - Is there another name for this?

Thanks again for your help.
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Old June 3rd, 2008, 06:59 AM
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Joe, I am watching this. I have had trouble finding a straight nipple with a sufficiently large thread size to fit the manifold at the local hardware store (in brass or any other material). I haven't researched intensely and was going to do some more work on it later as I got closer to completion on the project. The local auto parts stores don't even know what I am talking about (this subject has been discussed before ad-infinitum).
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Old June 3rd, 2008, 08:22 AM
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Something like one of these:

https://www.dormanproducts.com/cgi-b...om_page=search

Dorman Products (purveyors of the HELP! line of parts at auto parts stores) has a lot of this stuff. The trick is knowing the right term to search for on their website.

www.dormanproducts.com
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Old June 3rd, 2008, 09:19 AM
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That's the ticket Joe. I just didn't know what to call it. I'll do a little bit of research on the Internet for "Heater Hose Connector". Thank you.
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Old July 5th, 2008, 06:48 PM
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2151 Edelbrock Intake manifold

I haven't had any luck yet finding a straight heater hose connector for my Edelbrock intake manifold. The local NAPA store has some different types of
connectors but not exactly what I need. Somebody out there has got to know exactly what size the the heater hose nipple that I need is. The closest I've gotten to the right part is a 1" threaded hose connector with the 3/8th" hose (just a tad too big to start the threads).

Anyone who has a 2151 manifold would have had to find a heater hose connector. The original heater hose connector is quite a bit smaller and will not work in the Edelbrock. Any help would be greatly appreciated. Thanks.
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Old July 5th, 2008, 06:59 PM
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Have you checked your local hardware store for a reducer bushing in the plumping section? This could let you use the original fitting at its size and adapt to the larger manifold hole.
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Old July 5th, 2008, 07:04 PM
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Originally Posted by esisson View Post
Thanks Joe. My car has no A/C. I'm having trouble finding a straight through connection to replace the Vac controlled valve. I'm hesitant to go into Autozone and ask for a straight nipple. LOL - Is there another name for this?

Thanks again for your help.
You can get brass bushings to make up the difference between the bore and the nipple at any decent plumbing supply or hardware store as a quick fix. Or leave it if it does what you want it to.
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Old July 5th, 2008, 08:12 PM
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The "straight nipple" Joe mentioned is a basic hardware/automotive item. I've usually heard them called a hose nipple, but others may say hose connector or hose barb. They'll have pipe threads on one end and a barbed or bulged hose connector on the other. To get the correct size you need to tell the sales person two things, pipe thread size and hose size. The pipe threads are nominal ID sizes. Generally I think Olds has 1/2" NPT by 5/8" hose on the back of the manifold were the hose connected. But it could be 3/8" NPT or 3/4" NPT.

As an approximate guide, the OD's are:

3/8" NPT = 5/8"
1/2" NPT = 3/4"
3/4" NPT = 1"

Remember if you are measuring where the nipple threads in, measure the outside of the threads. Plus the threads are tapered, so the hole will be slightly smaller then the numbers above.

I've seen these nipples at Autozone and other places in the Help! section as stated above. NAPA usually has a drawer with assorted sizes.

Once you know the correct size tell the sale person you need a 1/2" NPT X(by) 5/8" hose nipple (hose barb, hose connector). If it's an automotive store you may have to do a little explaining about what the part is.

Hope this helped a little.

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