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1973 Charger 400-Thermoquad iron intake blocked or not?

Started by WH23G3G, November 15, 2015, 09:44:14 PM

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WH23G3G

Ok I'm going to give this another try with no success or reliability with the current Edelbrock 1400 and Weiand aluminum action plus intake I want to try all original. I've got the original 1973 400-4bbl intake and the original 6321S Thermoquad that I want to install back on my 1973 Charger 400. It ran and drove ok this past spring when a mechanic came over adjusted the timing, carb, and lef the vacuum advance unplugged. But I need to start driving this Charger more often because it just sits in the garage. I do try and start it up and let it run for a good while whenever I can. I know it ran the best it ever did when it was new from the factory so if I install the original iron intake and thermoquad after it's sent off and rebuilt, should it be more reliable than an aftermarket carb and intake if I'm not concerned about 1/4 mile and more horsepower? If putting the original intake back on with the choke, choke heater switch should I use the valley pan and the fiber gasket with the block offs to make it more reliable? I've currently got the original dual snorkel air cleaner with the heat stove connected. Would an open chrome air cleaner aid in preventing vapor lock? Mainly I want to totally avoid the vapor lock again in the summer when it gets 90s+ here if that's possible. Because it shut off wihtout any warning in the middle of the busiest intersection at rush hour 5:30 in the afternoon. It took a good few starts to get it going again and had to limp it to a gas station and come back later in the evening and drive it home. Right now I've got vacuum advance hose unplugged, the Weiand Action Plus intake, the Edelbrock 1400 and the heat insulator gasket Edelbrock recommended, a rubber high temp silicone hose routed the same as the original steel line into a new stock fuel pump. It gets quite hood under this hood. Some old timers suggested adding a low pressure electric fuel pump back in the back by the tank to help, but I don't want to cut my new oem fuel lines. Plus will it really help? Short of fuel injection what's the most guarenteed stop to vapor locking on these old cars? How come these guys on Graveyard Carz, Counting Carz, and Fast and Loud never seem to have carb problems? Are they doing something different or just not talking about it? But for Graveyard Carz none of these other seem to do quite as many Mopar builds.

ws23rt

I really like this question.  :2thumbs: Much has been said on this topic but I too am still left wondering what's going on here? --Is it just the gas we use these days??

WH23G3G

It's been suggested to the gas is part of the problem too. I use 93 octane but was also told to add some racing fuel to top it off but haven't tried it. I've seen so many restored cars at car shows driving their perfectly restored cars having no problems driving to shows miles away. So there has to be a way to cure the problem.

ws23rt

I agree. I have two cars that are stock and I have the problem of fuel boiling out of the carbs at cool down.  I drove these things for years then and since they came out without the trouble I have today. :shruggy:--The fuel must be a part of that but may not be all of it.

femtnmax

I have an ebody with 440.  The car does not overheat, but with todays gasoline it will not run reliably without an electric fuel pump, back by the gas tank is where I located it.  From the electric pump 3/8 line runs to Carter mechanical pump, then thru 440/hemi vapor separator, then to carb, which as 1 inch thick phenol carb spacer.I tried the open heat crossover passage but the carb got too hot, and the coil was so hot you almost couldnt touch it. So closed off the heat cross-over.
The electric pump solved most of the fuel boil problems, but not all of them.  On hot days slow driving around town the darn fuel boils in that hot mech pump, even with the electric pump running.  Wish they would make a mech pump that included a ceramic heat isolator gasket between the pump and engine block.  The OEM spacers I have seen were a little over 1/4 inch thick...the 440 would probably need a thicker one.  
My next plan is to eliminated the mech pump all together, and run two electric pump in-series and keep the vapor separator and carb spacer.  Maybe no heat cross over though.  The electric pump I'm using is for street use, low pressure, and has a built in pressure regulator...read the original Mallory spec sheet...
http://www.summitracing.com/parts/msd-29256
When I worked at Westinghouse we ran 3 pumps on certain systems for close to 100% reliability.  Note that only one pump was necessary to operate the system, and the additional pumps were to meet the reliability requirements.    Ford in their LeMans days ran 2 fuel pumps in-series and had no issues with fuel starvation or break-downs.  So there is my reasoning.
Just what I've been trying for reliable street use...not to say it is the final answer.   :Twocents:

Phil

ODZKing

Mine is a 73 400 HP and I also have the 6321S Thermoquad. I put mine all back together as original mainly for looks.  And once I found someone who knew how to adjust the TQ, it has been fine.  But I will say, I was ready to take it off as it ran awful. It is now running fine with the exception of after it sits for a while and first starts up.  It spits and sputters but once it warms up it is fine.
The one thing I wish I had done and will one day is get the valley pan that has the ports blocked under the carb.  The intake paint on either side of the carb is burned off, twice now. As long as the choke portion doesn't work well anyway I will live with it and rather not have to keep repainting the intake.
And again once I got it adjusted properly, it runs great.  My  :Twocents:

Dino

When I bought mine, 69 with a 440, it had an aluminum Edelbrock Performer intake and a 750 Performer carb.  Ran decent but not great and had the typical hot star issues.  I removed the valley pan and installed a new one with blocked crosover which made a huge improvement. 

After a lot of reading and asking questions, I rebuilt and set up the 6545S TQ that came with the car, bolted it in place of the Eddy and was blown away by the crisp throttle response and performance increase.  The little bit of hot start issue that remained with the Eddy disappeared thanks to the phenolic bowl keeping the fuel cooler.  I just ran the stock 1/4" base gasket that came with the rebuilt kit.

I've run this with an open air cleaner and a 71 dual snorkel with no noticable difference.
The only issues I had were starting it in cold weather without a choke, and letting it sit for more than a day which would result in the fuel evaporating leaving me cranking for a few seconds.

The TQ has done its duty and will be replaced but if you have one that's setup right they are excellent carbs.   :yesnod:
Extraordinary claims require extraordinary evidence.

BSB67

Vapor lock is usually not related to carb and intake, it is usually between the tank and carb.  But making the fuel cooler anywhere in the fuel system is always a good idea.

If the car dying after some run time is the problem, have you checked you gas cap?


500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes
4150 lbs with driver, 3.23 gear, stock converter
11.68 @ 120.2 mph