correct filler neck for 70 swinger 340?

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cli55er

cli55er

Tem Greene's Nephew
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car had wrong gas tank.....replacing it with a non-vented one. the one that was on there had a single vent at the top front center.

but I suspect it also has the wrong filler neck on it.

this is what is on the car now. the tube went through the trunk seal into a hold in the frame section of the car.

http://www.ebay.com/itm/171426119150?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

But is this one the correct one for a Non-Vented tank?

http://www.ebay.com/itm/360938668372?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

while I'm in here....has anyone had problems with vapor locking with the factory metal line to the carb with factory metal fuel filter??

thanks for the help
 
All A-body tanks are vented one way or another. The tanks up through '69 everywhere (plus '70 except California) have a simple single vent to atmosphere (it has a high loop in the vent line in the trunk to prevent liquid fuel drooling out onto the ground). Vent outlet between tailpipe and fuel tank (can be fun when the exhaust guy's not paying close attention to where he's pointing his torch). Single vent at top front centre is '72-up tank. See here for info including the 4-vent '70 California + '71 50-state/Canada tank. If your car originally had California emissions, it would've had that 4-vented tank (and a cap that is very difficult to find). If I were working on a car like yours, trying to optimize for function (rather than doing a 100-point accurate-to-1970 concours restoration) I would use the '72-up style tank (the kind you have now) and put a charcoal can in as described at the link. I would also use a '72-up filler neck to make life easy on myself when looking for a gas cap.

People use that phrase "vapor lock" to refer to a lot of different symptoms. What exactly are you experiencing?
 
the tank I bought has no vent in it at the front center. the car never had any charcoal canister on it, so the tank that was on there was wrong and that was why the vent was plugged off, obviously to keep gas from spilling out.

the filler neck seems to be correct that is on there since it has to vent somehow, so i'll keep the original filler neck tube.

the gas cap that has been on the car for decades looks like to me is vented. it has a little hold inside of a plastic piece on the underside of the cap.

the problem I call vapor locking I originally thought was ignition related. I changed the car from points to the mopar electronic ignition to eliminate that as a problem. new system works fine.

car was running fine and I drop to a gas station and waited for my wife with the car idling. it was fine, then about 10 min later it started to act like it was going to die and it was down on power. so I revved the gas and it reved up fine. got my wife to hurry up....thinking I was loosing the ignition again....and we took off. car drove fine down the road. then I dropped it down to 1st gear and floored it.....got to the top of 2nd gear and it started to just give up....like no power...or lack of ignition or gas. I got out of it and it drove fine again.

the car used to have an aftermarket fuel pump with rubber line going to the carb. I put the stock style fuel pump on it....but high volume version (brand new).....with the correct metal lines with metal fuel filter going to the carb.

my only thoughts are this.....picked up trash from the tank that was stopping up the fuel pump dropping pressure and not keeping up at WOT. (when I dropped the tank today...the sending unit had no sock on it....no idea why. and it did have some minor sediment in the tank)

or the other thought is that it is vapor locking.....which is why it did it after idling for 10 min.

when I got home I let it idle and it did fine. granted the hood was up. checked my timing and all was well.....so I'm clueless.

can't blame it on points anymore...so it has to be either vapor lock or trash getting to the fuel pump dropping pressure.

fuel pump registered at 6.5 psi when I tested it.

or maybe it is just shitty gas...crap gas with water in it. but I saw no floating water today when I looked into the tank.

my dad wants to go back to the rubber line, but I hate the way it looks...I like the metal line with the stock filter.

carb is a brand new edelbrock, which when this problem first start I took the top off and checked for trash...there was none...and I cleaned the passages to make sure.

here is the link to my project blog where you can see all the stuff I have done. I'm putting in a new gas tank, trunk seal, neck seal, tank pad, ss gas line, rubber hoses, sending unit, etc.

http://www.forabodiesonly.com/mopar/showthread.php?t=263029
 
cli55er said:
the car never had any charcoal canister
Click to expand...

Right, those weren't factory equipment til '72. I'm saying there's a better result by keeping the tank with the vent fitting and adding the charcoal can, rather than changing the tank.

cap that has been on the car for decades looks like to me is vented. it has a little hold inside of a plastic piece on the underside of the cap.
Click to expand...

That's a pressure-vacuum cap as described at the linked article. Factory equipment on '70+ California and '71+ 50-state/Canada cars.

car was running fine and I drop to a gas station and waited for my wife with the car idling. it was fine, then about 10 min later it started to act like it was going to die and it was down on power.
Click to expand...

The key to figuring this out is to determine whether it was gagging (loading up, too rich, too much fuel) or starving (leaning out, not enough fuel).

carb is a brand new edelbrock
Click to expand...

Thick insulator and/or heat shield between carb and intake?
 
new non vented tank already bought. not turning back there. it does have some hot restarting issues that I'm sure the ECS will help....but its a weekend warrior and driver quality....so no biggie. the filler neck has the vent at the top like that one in the ebay auction I linked too....but I'm wondering if I should have that vacuum cap? it does say vacuum pressure on the under side of the cap....should it be a non-vented cap for 70 swinger 340 no California car?

the insulator I believe is the one that came with the edelbrock carb....I think....I just measured it and it was 1/4" thick. I may have used the one that came with the Daytona carb rebuild kit I bought for the original AVS carb before I bought the edelbrock. i'll have to go look in the carb bock to see if I have a thicker one.
 
the carb gasket is the thick one....the others I have are like 1/32 or 1/16" thick....very thin
 
pretty sure its starving for fuel...when I give it gas it straightens out.
 
But remember, when you floor the accelerator, you're also letting a lot more air into the engine.

It does sound heat-related; I'd look at a thicker carb base insulator and a heat shield. Also note the MP electronic ignition is not a good pick (without tweaks) for street driving, and reliability on the MP modules has been "poor and getting worse" for quite a few years now.

Non-vented cap would be correct for a '70 non-California car, but no harm or trouble comes from using a pressure-vacuum cap on a car that doesn't need it (what you can't do is the other way round, unvented cap on a car that needs a pressure-vacuum cap).
 
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