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Installing a 1972 Holley 1920 in a 1973 Valiant
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Author:  MattyBrown [ Tue Aug 03, 2010 12:04 am ]
Post subject:  Installing a 1972 Holley 1920 in a 1973 Valiant
Thanks to everyone who responded to my question about my Vacuum Amplifier but unfortunately, turns out the question was pretty much pointless. I'm going to have to scrap the Vacuum Amplifier. Here's why:

The Holley 1920 in my '73 Valiant is making it run like crap. I didn't realize when I bought the car that rust was being carried through my fuel lines, straight THROUGH the cheap plastic fuel filter into the carb. After a few good drives, the carburetor will not allow the motor to get a smooth idle. It's rough as hell and the car wants to stall out constantly, even after doing a "quickie" rebuild on the carb and flushing everything out. I think to save this carb it would have to be professionally rebuilt. I was thinking about sending it to Buzzard, but then...

I got my hands on a supposedly good running Holley 1920 from a 1972 Satellite with a Slant 6. I'd like to give it a try. My question for you folks is: Can anyone tell me if there's anything I should know about the differences between the 72 and 73 setup? I'm already ignoring the OSAC and I plan to just ignore the EGR valve until I can get a plate. But is there anything else that might throw me for a loop? Am I correct in my belief that there was no Vac Amp in the '72 setup? My Vapor Cannister has three connections. Is that the same as the ones in a '72? If anyone happens to have an "under the hood" diagram of a '72 setup that would be great.

Any advice is GREATLY appreciated. Thanks guys!

-Matt

P.S. Rust problem was taken care of. New tank, blew out the lines, new METAL filter.
Author:  MattyBrown [ Wed Aug 04, 2010 8:11 am ]
Post subject: 
Here's a picture comparison of the '72 and 73' carbs:

ImageImage

Here's how my '73 carb was connected when I got this car:

RED - Connected to nipple on Cannister marked "Carb Bowl"
ORANGE - Connected to nipple on Cannister marked "Purge"
YELLOW - Connected to PCV valve on Valve Cover
BLUE - Connected to distributor (after bypassing OSAC).
GREEN - Connected to Vacuum Amplifier.

So, I guess what I'm really confused about it what to do about the lack of place to hook up "Purge" from the Cannister. Any insight anyone? THANKS!
Author:  Aggressive Ted [ Wed Aug 04, 2010 10:31 am ]
Post subject: 
Take a look at the bottom of your 72 carb and see if is the same as the 73 in terms of cut outs and cavities in the base. The orange arrow is pointing to a ported vacuum fitting that goes to the purge port on your vapor canister. You might be able to drill the 72 and screw in a brass fitting. I don't have a 72 carb at the moment or I would check.

The only other option would be to not hook up that line for awhile until you can get the 73 and cleaned out and rebuilt.
Author:  ceej [ Wed Aug 04, 2010 7:32 pm ]
Post subject: 
If you have an excellent understanding of the carburetor in question, and know precisely where you need to drill the hole to install the port, and the correct orifice size, that's one thing.

The better options would be to obtain the correct carburetor, or simply run without the purge. Running without the purge will not result in serious problems unless you need to have the purge hooked up to meet emissions.

CJ
Author:  Eric W [ Wed Aug 04, 2010 9:00 pm ]
Post subject: 
The purge line on '72's goes to a T fitting in the vacuum advance line. I had a '72 Satellite, and if I remember right there where four connections on the canaster. One for fuel tank vent, on for the float bowl, one smaller diamater hose went to a T in the PCV line, and the purge line mentioned earlier that connected to a cap on top of the canaster.
Author:  MattyBrown [ Wed Aug 04, 2010 10:59 pm ]
Post subject: 
Hmm. This is tough. Part of me WOULD like to have the correct 1973 Carb in my car. But then I think about it and remember that I'm already planning on pulling the EGR and blocking it with a plate. So really, what's the point of using the '73 carb? A '72 carb should be perfect for all of the equipment I want to use. And I definitely don't dare mod the '72... I don't know enough about what I'd be doing.

Not that I'm doubting your memory of a 4 connector canister Eric, but I did just see a listing on eBay for a NOS Vapor Canister, with 3 connectors, and it is listed for years 71-76. Of course the person on eBay could be wrong... or perhaps there were different canisters for different setups like AC or no AC. I don't know, I'm just making guesses. But it would make me rest easier if I knew that my canister would be (or COULD be) a correct part for both '72 and '73.

Either way, is it safe for me to assume that the Purge will work correctly if hooked up to a T-connector in the Vac Advance hose? That sounds like a pretty easy setup to pull off.

I'm still hoping someone out there on this forum currently has a stock '72 setup and can tell me definitively what to do. If not, I might just do what Ceej suggests and run it without anything connected to Purge. I'll give it a few more days and see if anything turns up. I'd hate to buy a 72 shop manual just for a couple diagrams.

THANKS FOR ALL THE INPUT SO FAR!!

-Matt
Author:  MattyBrown [ Sun Aug 08, 2010 11:04 am ]
Post subject: 
PROBLEM SOLVED!

Thank goodness for SlantSixDan who offered me some offline help on the matter. He sent me in the direction of some earlier posts he wrote regarding the correct setup of purge on the canister.

Eric W, let me apologize for not wanting to hear what you were saying. You were right all along, it's just the way you were describing it from memory wasn't making enough sense for me to fully comprehend it. It sounded complicated and I wanted to deny it. But here's the ultimate truth:

A 1972 carburetor doesn't have a built in "purge port" so the system is reliant on an additional part that my 1973 didn't require... a Purge Valve which sat on top of the canister. Since mine didn't originally use one, I've had to order a stand-alone purge valve from NAPA (part #2-28011).

Here is a quick diagram I threw together to show how the Purge Valve should be hooked into the system.

Image

Right now, I'm stuck waiting a few days for the part to arrive. Can't wait to get this carb hooked up correctly. Thanks everyone for offering suggestions!

-Matt
Author:  gato [ Sun Aug 08, 2010 12:05 pm ]
Post subject: 
i would have suggested, had i seen this post soon enuff to try swapping the carb base plates untill u get the 73 back to working condition.
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