Hi everybody,

I recently got Grandmas 1970 Plymouth Duster out of storage where it has sat for maybe the last six or seven years and after the appropriate TLC to get the fluids happy again she is running like a dream (with only 58,000 original miles I'm not surprised) but I've got a strong gas odor coming from the carb.

With my limited knowledge of such things I believe I have traced the source down to what the Chiltons says is the Hot Idle Compensator Valve. It appears the Valve Plate is completely missing and maybe even the valve itself as there is just a cavity there with nothing in it that I can spot. Now, I've done some research online and it seems as though this was a misguided attempt to create a controlled vacuum leak to let the car idle better at temperature. I guess I have two questions.

1) Since the general consensus is you don't need to have this, is there any way to adequately seal the hole and close the vacuum leak?

2) I've been looking for a valve replacement but I cannot for the life of me find anything. Does anybody know where I might be able to find a HIC valve and plate?

Thanks.

Oh, almost forgot it's a 1970 Plymouth Duster 225cid /6 with a Holley 1920 1bbl carb.

Can you feel a valve leak? There may not be any holes. Mine has the cast pocket but no hole or leak.

Best bet is parts from another carb.

1) JB Weld will seal the hole if there is one.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Whoah, hold it, let's not be gooping anything up with JB Weld just yet!

One of the problems with the Chilton (and Haynes) books is that they consolidate the many different versions of every part and system into generic information that usually doesn't directly apply to exactly what's on your car. Many carburetors have the casting provisions for the hot idle compensator valve, but do not actually have the passages drilled or the valve or plate installed. If the HIC valve were actually missing from a carburetor supposed to have it, you'd have an enormous vacuum leak and great difficulty getting the engine to idle smoothly or at the correct speed.

For reference, the HIC valve was not a "misguided" anything. I'm not sure what would lead you to that belief. Its job is to countervail the tendency of high carburetor temperature to create an overly-rich mixture. It does so by admitting extra air above a certain carburetor body temperature. It's an effective and largely trouble-free item on carbs that have it. But yours probably does not.

Step "number zero" is to get the three books described in this thread and start reading.

Tune-up parts and technique suggestions in this thread.

Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

Your carburetor probably needs a careful rebuild with a kit from www.daytonaparts.com and a new float, Walker part number 100-14. The float is made out of foam and absorbs fuel and grows heavy over the years. Moreover, doing the fuel line mod will greatly reduce fuel heating that tends to cause or aggravate gassy smells around the car.

But be advised that unless your '70 was built for sale in California, it has an open carburetor bowl vent; there will always be some gassy smell after shutdown. If this is your first experience with a pre-1970 (California) pre-1971 (rest of North America) vehicle, you may not have realized that this what you describe is, to some degree, normal.

Welcome on the board!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Taking this information I went back to the car and tried to see if there was any suction at the HIC valve port and putting my finger over the opening I could not feel any suction at all. The car was idling pretty rough which is what led me to this path in the first place but after a few days of driving it seems to have smoothed out. Guess we just needed to finish blowing the cobwebs out of it.
Pardon my over-zealousness. I had read a few posts from someone who was probably as frustrated as I was about having to repair their HIC and they made a bold statement that I blindly assumed was factual.
Thanks for all the great links. I'll be buying my books next month as I shot my play budget getting the car running again. After re-investigating the HIC valve port and not feeling any suction there I was poking around again and it seems the leak is around the float bowl. I'm definitely going to buy the rebuild kit and just go over the whole thing.
Talked to my Dad last night and he said the car was purchased in California and moved to Colorado shortly there after. I'm going to dig through some old paperwork and see if I can't find the original window sticker. I wouldn't be surprised if Grandma kept it all these years.
Thanks! You've been a great help and are a wealth of information. My ultimate goal is to get this converted to a Hyper Six so I'm sure I'll have more questions once that day comes.

Show us a clear, sharp photo of the fender tag (2" x 3" metal tag on the driver's side inner fender, visible with the hood up) or carefully transcribe its contents exactly as they appear, and we can tell you a great deal about how, where, and when your car was built.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Here is the tag you requested



Here is the carb with what I believe to be the HIC valve port:

Yup, that's the HIC chamber. Your carb originally had it, and someone removed it and drove steel or lead shot balls into the ports to block it off.

Your car decodes as follows:

V: Plymouth Valiant/Duster range
L: Low price/trim class
29: 2-door sports hardtop (Duster/Demon)
C: 225 cubic inch 145bhp 1bbl Slant-6 engine
0: 1970 omdel year
B: Built at Dodge Main plant, Hamtramck, Michigan
172520: Vehicle serial number
E24: 225 cubic inch 145bhp 1bbl Slant-6 engine
D31: A904 Torqueflite 3-Speed automatic transmission, standard duty
EV2: Hemi Orange exterior paint, PPG paint code 2186
D2X9: Interiort trim - Deluxe vinyl bench seat, black
TX9: Black Interior door frame paint
A31: Build date: 31 October 1969
132028: Vehicle order number
EV2: Hemi Orange roof paint, PPG paint code 2186
A33: Track Pak w/3.54 rear axle
M21: Roof drip rail moldings
M31: Belt Moldings
N95: California emissions control
R11: Radio, 2-watt Music Master solid state
V8X: Tranverse stripes, black
Y05: Built to US market specifications
EN2: End of codes

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Wow, great info. Thanks so much!

Interesting on the HIC valve. I'm going to have to ask the family mechanic if he remembers ever doing that.

Do you know if there is anything else I need to worry about with the California Emissions as I go through the carb, or any other part of the car for that matter?

Here's a pic in her current condition. It was repainted in the 90's and they didn't get the decals or emblems back on right so learning about the Transverse Stripes was great.

Y'welcome. I'm not too sure on that A33 code. It would be not impossible but strange to see a 3.54 Track Pak (8¾") rear axle in a slant-6/auto car. I've got another source calling A31 a 3.91 rear axle ratio, which is equally possible-but-unlikely. You probably in fact have a 2.76, 7¼" rear axle; that's how most slant-6/auto cars were equipped.

See here for info specific to the '70 California (and '71 50-state) cars. Don't lose the gas cap; it's a very difficult one to find!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.