1965 Dart 4 BBL Conversion

[PocketAces]

I got a pair of 4 bbl Carter AFB's from a guy I met at Spring Fling along with a 4 bbl intake, air cleaner, and two sets of commando valve covers.

I didn't know how to identify them, but with some help from FABO, figured out that they were correct carbs for my 65 Dart with automatic transmission.

http://www.forabodiesonly.com/mopar/showthread.php?t=186423

Here are some before pictures.

 

[PocketAces]

Picked one to rebuild and tore it apart.

 

[PocketAces]

After soaking the carb and all the parts in lacquer thinner for 2 days, I soda blasted everything to get it all looking nice.

Couldn't quite get the metal looking perfect. You can see some discoloration in the second photo.

 

[65dartcharger]

Great job on the carb! Do you have all the other stuff, distributor,air cleaner, valve covers etc?

 

[PocketAces]

Both the carbs were missing all of the air horn screws and the accelerator pump linkage. So I bought a donor carb at Chryslers at Carlisle for $10. I think it was off an old pontiac, but it had what I needed.

After getting pretty far along on the assembly, I realized that there was a tab broken off of the end of the secondary shaft. Figured out that this tab was part of the mechanism that keeps the secondaries from opening when the choke is on. Not sure if that's important. Maybe somebody broke it off on purpose. Contemplated trying to swap the shaft from the donor carb, but after I broke the first butterfly screw I decided not to risk it.

Started over with the other carb. After soaking it all night, I soda blasted it and started over on the assembly.

Made all the adjustments described in the factory service manual. The only one that didn't make sense to me was something called the positive closing shoe adjustment. If I set the gap at .020 with the butterflies closed, the shoes would interfere with each other just off idle. Didn't feel right. So I opened up the gap just enough so they never touch each other. If someone can explain the purpose of these, it would be good to know. Seems like a safety feature maybe?

 

[PocketAces]

Great job on the carb! Do you have all the other stuff, distributor,air cleaner, valve covers etc?

I'm running a modern HEI distributor. It has the ignition module on board and back by the firewall where it's hard to see. I bought a black female cap and a bottle style coil. It all looks stock enough and runs really well with zero maintenance. I have the valve covers and the air cleaner.

 

[PocketAces]

Time to do the swap. Here are some before and during pictures.

 

[PocketAces]

Got the intake on and torgued it down. Man those 5/16" intake bolts make me nervous. The manual says to torque them to 270 in-lbs. I got them to 200 in-lbs and decided that was good enough. Didn't want to be messsing around with easy-outs on my holiday weekend. Well it wasn't good enough. As soon as the engine got warm, it started leaking anti-freeze on three corners. Dissasembled and torqued to 270 in-lbs. and no more leak. I used fel pro blue gaskets and I used the cork end gaskets.

This intake will probably only be on this engine for a month. I want to get the 4 bbl tuned and debugged so that it starts right up and runs smooth on the new engine during break in.

Did I mention the engine started right up after just a few seconds to fill the bowls! Idled smooth too. I spent some time fiddling with the idle speed, and idle mixture adjustments. Choke seems to work right too.

 

[PocketAces]

Had to fabricate a bracket for the throttle cable hold down. I used the 2 bbl piece to make a paper template. Then I lengthened the vertical section a bit, based on pictures posted by 65DartCharger.

 

[PocketAces]

Put the air cleaner on and took if for a drive. Seems flat in the midrange, perhaps when the secondaries open. Didn't want to drive it too much without the kickdown linkage.

I don't want to alter my 2 bbl kickdown rod, so I need to make a junkyard run to scrounge some pieces to make a longer rod. If anyone has a photo and/or dimensions of the kickdown rod for a 1965 4 barrel, it would be a big help.

 

[Oldschoolcuda]

Very nice work. Carb looks great. On a side note, the carb to bell-crank rod for kick down was slightly longer on 4bbl set-up than 2bbl. Correct piece is hard to find but if need be the 2bbl unit can be lengthened. Stock 2bbl rod will work but not give you correct kickdown travel. We modified a friends by cutting in half, treading both ends then adding coupler.

Oldschoolcuda

 

[Oldschoolcuda]

Here is pic of original 4 bbl setup. Have also seen them made out of threaded stock. You can also go with 67 up setup.Just make sure you have full kickdown at full throttle with however you modify. Never ever drive without any kickdown linkage even if just around the block. Good luck & keep us posted.

Oldschoolcuda

 

[PocketAces]

Went to the local Pick Your Part and got something I could adapt for the kickdown rod. It was the throttle rod off an early 70's dodge van, not the kickdown, but the rod that opens the throttle when you push the gas pedal. It was longer than I needed but had the right kind of ends. I cut it down, removed one bend, and welded it back together.

When I adjusted it to get full travel at wide open throttle, it wouldn't let the carb return to idle. So I had to set the adjustment to allow idle. Seems to be getting enough travel to downshift when I floor it, so I guess it's good.

Actually as I look at these pictures, it seems like the increase in length could have been achieved just by screwing the longer end from the 70's van onto the original 2 bbl rod. The new rod does have a longer threaded portion too.

 

[PocketAces]

Drove the car to work. Runs great at high speed and definitely wants to rev. I now understand why they call it an "unsilenced" air cleaner.

The problem is that it's flooding if I let it idle too long. Once it stalls I have to floor it and crank a long time to get it to start. It's doing this even when warm and the choke is fully off. Even after it dies, I can still see gas dripping down onto the primary butterflies for a while until the pressure in the fuel line bleeds off.

I screwed the idle mixture screws all the way in and the engine still idles for a while, so it's clearly getting too much fuel. When I first fired it up, the idle mixture screws worked as they should and I got the lean drop off when I screwed them in too far. So this is a new development that was not happening when I first started it up.

Tonight I'm going to test the fuel line pressure. How much pressure is too much? Can a mechanical fuel pump make too much pressure? The 2 BBL worked fine with that pump.

I'll also pull off the air horn and see if there is any dirt in the bowls and also see what happens if I blow on the inlet.

The carb kit directions and the factory service manual both called for 7/32" float level. Does that sound right? I did read one post online that claimed the specs are always about 1/8" too high.

 

[rigrunner]

do you have a heat insulator under the carb or phenolic spacer? my edelbrock did the same thing and it was getting so hot it was boiling the gas out at idle. good luck. looks great.

 

[gtmopar]

Man I am so sorry about getting you info on that throttle bracket, I've been out of town for the last few weeks. Looks like you did an excellent job replicating it.

 

[gtmopar]

Back when my dart was stock I use to have a hell of a time starting it after the motor was hot so I figured I needed a spacer because it was boiling to fuel so I put one on and it still was hard. Although it got better it still did it so I put a huge ground cable on it and it solved all my issues.

 

[toolmanmike]

Great job on the carb. That soda blast does the trick! Your 4 barrell conversion will be fun! tmm

 

[dodge freak]

Make certain the floats do not have any leaks and are they adjusted right ? Lower float level or new floats or a leaky needle / seat might all that be wrong. A spacer is always nice to use.

Looks great but I'm let down, I thought you were going to use both carbs and go dual quads like many of the old 273's

 

[PocketAces]

Looks great but I'm let down, I thought you were going to use both carbs and go dual quads like many of the old 273's

I'll be happy to just have one of them working right.

 

[PocketAces]

The car ran better on the way home this evening. Didn't flood until after I climbed a long hill. Maybe this is temperature related?

I picked up a vacuum / fuel pressure tester at Harbor Freight and T-ed into the fuel line just before the carb. I let it idle for a long time and the needle stayed very steady at just above 8 1/2 PSI. I let it idle for at least 15 minutes and it didn't flood the whole time. The engine was already warm from the drive home.

8 1/2 is a bit high. The FSM says the fuel pressure can be between 3 and 7 psi depending on the pump. Could 8 1/2 be enough to overcome the pressure supplied by the float? I called O'Reilly Auto Parts. The pump they sell goes up to 7 1/2 psi at the high end of the range. I'm skeptical that 1 psi could make the difference, but welcome other opinions.

I incorrectly stated that the float level spec was 7/16". Actually it's 7/32" which is what I set it at. I read a post somewhere by a guy who claims the spec is always too high and he always sets them 1/8" lower. If I can't find anything else wrong I may try that. According to Archimedes, I should get more force on the needle if the float is sitting deeper in the fuel.

I guess the next step is to pull the top off the carb and see what's going on.

 

[PocketAces]

do you have a heat insulator under the carb or phenolic spacer? my edelbrock did the same thing and it was getting so hot it was boiling the gas out at idle. good luck. looks great.

No, just a paper gasket. Did you have this problem all the time or only on really hot days after running it hard?

 

[rigrunner]

mine did it all the time when i just had a paper gasket. would flood and not idle but run fine as long as you were gassing on it.

 

[d273]

No, just a paper gasket. Did you have this problem all the time or only on really hot days after running it hard?

I have had my 273 since 1976 and after the first rebuild I had this same problem. It took alot of time and attemps to get it solved. If you use the standard "small block" intake manifold gaskets most will have large holes for the exhaust gas where it passes under the carb. This is for perheating in cold climates and the choke. Some gasket sets will have several sets of intake gaskets with different size holes and if you are lucky there is one that does not have the exhaust gas preheat hole. Take the gasket with the smallest hole and put it on the choke side. Take the gasket with no hole and put 1/4" hole in it and use it on the opposite side. I did this about five years ago and have had no problems and this is after sitting in Atlanta traffic in the summer. If you are burning the paint on your intake manifold on the drivers side then you are getting too much heat to the carb. By the way I run just a standard gasket under the carb.
Hope this helps

 

[RedFish]

Carquest store ordered the kit for my AFB #4305S. The new needle seats in the kit were slightly taller than the originals ( Took quite a while to discover this little difference ). With the needles closed and the float paralell with the top the float wouldn't drop far enough to open the gate. Adjusted to open right put the fuel level too high at gate closed. Some fancy tang bending was required to make them work right. I had to trim the slosh baffle in the bowl a little also.
May not be relevant to yours but couldn't hurt to double check, compare the new seats to those removed. Good luck with it.