Experienced with 413 inline dual quads?

[62 Dart Convertible]

Does anybody have experience in tuning carbs on a 413 inline dual quad? Just got my first B Body, a 62 Dart 440 ragtop, which when warmed up, idles too fast. Easy I thought, just turn down the idle speed screw on the front carb, only problem - there isn't one. It has a fast idle speed adj screw that contacts the fast idle cam when it's cold, but no other adjustment for base idle speed. Also I notice there is a large hexagonal head adj screw located between the mixture screws on both carbs that are screwed all the way in. I'm guessing these are perhaps idle air bleed screws and may be how idle speed is adjusted, but they are screwed shut and still the beast idles too fast.
Can anybody shed some light?
I got a factory manual on CD for the car, but it does not contain info on this engine as I was told it was a mid year option (300H engine) not avail at model release and thus not in the manual.....

 

[64BEL]

Frank,

Check this out - it may help. I've heard good things about this tool. I don't have one yet myself, but I plan to get one for a future cross ram.
http://www.dvorakmachine.com/carb_sync.shtml

 

[Meep-Meep]

Early 426 HEMI carbs function the same way, so yes, I can get you close. First you will notice two idle mixture screws per carb as usual but in between them is a big brass hex bolt with a spring and a screw driver slot. This is an air bypass and is your idle speed adjustment. The throttle blades on both carbs need to be seated in the bores so make sure you have nothing interfering with that. Set mixture screws on both carbs about 2 turns out from lightly seated and the brass plug (5/8" hex I believe) about 3/4 out turn from lightly seated. Start it up and hopefully you will be around 900 RPM. Turning the brass screw clockwise lowers the idle. After you get the idle set readjust the mixture. There is kind of a balance between the air bypass and the mixture. Also before you start make sure the timing is set properly.

 

[62 Dart Convertible]

Thanks for the replies fellas. OK, so these carbs do have air bypass adjustment??!! These are screwed down tight and yet engine still idles too high. I can only imagine the problem is throttle blades that aren't shut fully or a vacuum leak (brake booster etc..). I haven't checked the timing yet as it could be that is way too advanced and part of the problem....

 

[62MAX]

What you need,hope you can read it.

 

[Meep-Meep]

Thanks for the replies fellas. OK, so these carbs do have air bypass adjustment??!! These are screwed down tight and yet engine still idles too high. I can only imagine the problem is throttle blades that aren't shut fully or a vacuum leak (brake booster etc..). I haven't checked the timing yet as it could be that is way too advanced and part of the problem....

Yep, just like early Volkswagen carbs! You definitely have air getting in from somewhere else or like you said timing too advanced, or the throttle cable adjustment may be off and not allowing the linkage come down all the way. After you check the obvious leak possibilities then you may want to remove the carbs and make sure the throttle blades properly seat in the bores.

 

[SUPERSTOCKRACER]

disconnect your throttle linkage 1st and go from there.

 

[62 Dart Convertible]

62MAX, thanks very much for the scan, that's exactly what I needed to see!!

Meep-Meep, thanks, shows you were on the money.

SSR, thanks, I did have the throttle cable, inter-connect rod and kickdown all disconnected, so I know that ain't the cause.

I didn't chase vacuum leaks though, or take the carbs off yet to see if throttle plates close well in bore or if throttle shaft is worn, these are next...

I won't get a chance to play for a few days while the car is at a resto shop getting a once over before it's roadworthy check. I will report back with what I find once I have a good look.

 

[crossram 426]

Hi 62 dart convertible where are you in OZ, welcome...

 

[62 Dart Convertible]

Hi 62 dart convertible where are you in OZ, welcome...

I'm in city of Churches (and home of bizarre murders), Adelaide. I have a sneaking suspicion you may be too, afaik I saw a red '63 Polara on a Zippel cruise..

EDIT - Thinking about it, it was a black one I saw on the cruise, doh!

 

[crossram 426]

yep the black ones been around your area for a couple of yrs now, orig polara 500, interior not my style.....I like original style......
My Polara came in through Phil Hart in Victor Harbour in 2001-2...so some connection, but I'm in Wollongong NSW.........hope to have all the bits together sometime soon and on the road for it's 50th birthday in April 2013.........

 

[62 Dart Convertible]

For the sake of closure, I thought I should come and report what the problem was. Firstly the timing was set way too advanced, but the main cause was the brake booster leaking vacuum......

 

[Meep-Meep]

That'll do it!