Chrysler /6 carb replacement

[Wilf Sedanet]

I bought the car late may, the previous owner did already do a lot of maintenance like new bushings, all kinds of new suspension parts, 'new' (DOT 4209 but lots of tread) tyres (Chen Shin; cheap Maxxis) and a proper alignment. The car feels quite modern in its handling as it is. I haven't looked at the shocks but the car keeps it tyres quite firmly at the ground and all the speed bumps Europe is full of are no problem. 

 

Since then I've changed out the engine oil, let someone set the valve lash (which was already quite good as I heard) so it is already quite a nice handling car. There is a little bit of a tremor in the drive line at 60 MPH that will resonate quite some more at 70 MPH (which we rarely drive anyway) so I guess the drive line is not precisely balanced as it was from the factory. 

 

It's not perfect but it's getting better all the time.

 

Attached are some pictures I made from the underside when I changed out the oil so you can see the new parts.

[Wilf Sedanet]

Wow Rusty, your suggestion made a huge difference! It not only kicks down again but at normal driving it shifts at around 15 MPH to the 2 and when stepping on it at the traffic lights it flies off and shifts to 3 at around 40/45 mph. I didn't even give it full spurs but this was modern acceleration and normal traffic is quite doable now. 

 

My girlfriend cannot handle the no-choke situation and when the engine is cold she stalls it a lot and she already had about 5 backfires. I have the idea that the carb now has a little stumble sometimes at transition between idle and pump. Could it be backfire damage? What is the carter's weak spot when it comes to backfires? It could also be the ignition and timing since it has been running badly and awfully rich with the previous carb and my friend mechanic did the timing for the old carb on the fly (feeling rather than with a strobe). I think that if this car would have a choke release* and proper timing and ignition parts it would really drive like a dream. 

 

Getting there!

 

* talking of which: would a choke thermostat of a '66 carter BBS work? These are the only ones on offer on eBay and the likes. My carb doesn't have the vacuum choke pull off and has no vacuum lines to make one. 

Edited July 17, 2017 by Wilf Sedanet (see edit history)

[Bloo]

I wish I could answer this more definitively.

 

Backfiring will almost never hurt a Carter carb such as yours. The fuel metering is done with a rod that moves up and down the main jet, so there is no rubber diaphragm to blow out. No worries there.

 

It is possible to mix parts and come up with things that do not work together. This engine ran from 1960 until the early 80s, and there are a lot of parts that are almost the same but not quite. I have seen 2 intake manifolds with the hole for the choke thermostat at different heights. I have also seen different lengths rods on the choke thermostat. One possible reason for this is that some cars had a spacer under the carb. Another possibility is the factory using about 3 different brands of carburetor.

 

Many slant sixes no longer have their original manifolds because they warp and break. Usually it is caused by improper mounting to the head (there are special washers that allow the manifolds to slide with heat expansion). Replacing one manifold often requires machining the angle of of the heat riser area to get the intake and exhaust ports all at the same height, and then machine the face that contacts the head because the intake and exhaust faces are no longer in the same plane. This should not be true, and would not be true with brand new parts, but with old warped parts it is usually the reality. To avoid this trouble, often the whole manifold assembly from another car will be substituted.

 

A very good first step would be to verify that your intake manifold is the one that belongs on the car, and if not, figure out what it does belong on.

 

Assuming it is the original manifold, you can likely just put on the correct choke thermostat and choke pulloff diaphragm, and then set the linkages up to original specifications.

 

Rusty hinted at this earlier, but driving this car should run good, even cold. On basically any late 1950's or 1960s Chrysler product, you should be able to do the following: Stomp the gas pedal once (or 2 times if it is below 0*F) to set the choke and give a squirt of gas. Hesitate a couple of seconds (more like 5 seconds if it is below 32*F) and bump the key. It should start immediately, and run at a very fast idle. Tap the gas pedal again. If its really cold out, let it run for 10 seconds or so before you tap the pedal. The Idle will come down to a slower fast idle. You can just drive away now. You probably cant stomp it all the way to the floor without a bog, but you should be able to drive away normally with no drama at all while the car is still cold. The car will come the rest of the way down to normal idle as it warms up.

 

I think the choke pulloff diaphragms for Carter carbs on a slant 6 were all the same up until 1969 or so, Carbking would know for sure. Many of those old pulloff diaphragms are discontinued, but can still be found on Ebay.

 

 

Edited July 17, 2017 by Bloo
typos (see edit history)

[Bloo]

Reading over your post again, I had a little bit to add.

 

14 hours ago, Wilf Sedanet said:

I have the idea that the carb now has a little stumble sometimes at transition between idle and pump. Could it be backfire damage? What is the carter's weak spot when it comes to backfires? It could also be the ignition and timing since it has been running badly and awfully rich with the previous carb and my friend mechanic did the timing for the old carb on the fly (feeling rather than with a strobe).

 

A stumble is probably one of two things. EIther the accelerator pump in the carb is weak, or the vacuum advance on the distributor is not working.

 

With the engine off, you can look down the carb throat and move the throttle. The squirt from the pump should start instantaneously when you move the throttle. If it does not it needs attention.

 

The vacuum advance should be plumbed to a "ported" vacuum port. It should be near the bottom of the carb somewhere. The actual port should be just over the top of the throttle. With any movement of the throttle, the port is now under the throttle.

 

Chrysler distributors are sort of picky about point gap. I would recheck the dwell and timing.

 

14 hours ago, Wilf Sedanet said:

* talking of which: would a choke thermostat of a '66 carter BBS work? These are the only ones on offer on eBay and the likes. My carb doesn't have the vacuum choke pull off and has no vacuum lines to make one. 

 

I am confused by this. Are there really no vacuum ports on this carburetor? The pulloff diaphragm probably attaches to the top with a couple of airhorn/bowl screws. It likely attaches with a u-shaped linkage that can be bent to set the pulloff. The carburetor looks like a mid-60s one with the usual 2 idle screws you expect to see on a Chrysler BBS or BBD with an automatic choke (it must actually be older because there is no PCV). The choke thermostat itself bolts into a little bowl-shaped area in the manifolds over near the head and pushes with a long rod, and attaches to the linkage with a little spring steel clip.

 

Do you have any more pictures of this Carter? Do you have a tag number? If you have the tag I'll bet Carbking would have some insight. The lack of a port for the choke pulloff really surprises me, what little I can see of the throttle linkage looks like standard Chrysler automatic choke stuff, and if so, it had to have the pulloff. Could it be an industrial carb or something?

Edited July 18, 2017 by Bloo (see edit history)

[Rusty_OToole]

In regard to Bloo's comments about the manifold. This is important. The exhaust manifolds are a known failure point. The big problem is over tightening of the manifold bolts. They MUST NOT be tightened over 12 foot pounds (16.26 newton meters).

 

The reason is the manifold 'grows' when it gets hot and must be allowed to expand and contract. If it leaks replace the gasket DO NOT just tighten the bolts, that is asking for the manifold to break in 2.

 

Later engines had a warning and torque figure cast into the manifold. If you have a good gasket and the manifold bolts are not over tightened there is little or no chance of damage.

 

Do you have the factory repair manual or any manual? The factory made thousands of manuals, every dealer used to have one and they come up for sale frequently. Worth its cost many times over, especially for someone like you who is far away from experiences mechanics and parts supplies. I can't help thinking if the previous owner, or his mechanic, had a manual and some common sense your car would never have been buggered up.

 

I was looking at Rockauto's site for carburetor parts, and found that they sell a DVD or CD/ROM of the factory repair manual and parts manual. This might be the easiest and cheapest way to get them.

Edited July 18, 2017 by Rusty_OToole (see edit history)

[Wilf Sedanet]

Thanks for your responses, guys. The carb has a tag but I didn't write it down somewhere. When I bought the carb it had zero vacuum points. There was this threaded orifice on the passenger side halfway up. It is here that the seller could screw in a vacuum tube and it is there where I installed the vacuum advance tube on. There are no other vacuum points on the carb. 

 

I had the (presumably) Holley thermostat attached and bent the linkage to a point that the car ran good cold, but because the thermostat linkage only goes one way and the choke linkage works with sleeves the car could suddenly stall after bumps or corners because the choke could fall open. 

 

To counteract this I installed a spring in stead of a thermostat rod on the choke that pulls it open all of the time. That spring is screwed in at one of the screw holes of the thermostat housing in the manifold. 

 

Attached are pictures of the carb and my PCV hack (and mitigation of the hot air problem of after market air filters to boot):

[Wilf Sedanet]

When looking over the first picture above I suddenly think: wait a minute, there is a round cap there blocking a vacuum port maybe…? It's the opposite of the one I used for the vacuum advance. 

 

By the way I bought a '64 Dodge (Dart) workplace manual at Faxon before my holiday and took it along. 

Edited July 19, 2017 by Wilf Sedanet (see edit history)

[Bloo]

Here are some pics I found online that show about where the port is and how the choke pulloff diaphragm mounts. Also notice how he made the missing clip with wire. That works fine if you dont have the clip. The original clip looks more or less like the third picture

 

I think the throttle linkage in the first picture is badly bent. One of the screws contacts that cam you can see for the various steps of fast idle. The other is the main idle screw and just touches something solid after the engine is hot and the choke is wide open.

 

 

 

 

Edited July 19, 2017 by Bloo
more (see edit history)

[Rusty_OToole]

Keiser31 knows someone who may have the correct carburetor, air filter etc for your car. You can contact him directly.

http://forums.aaca.org/topic/296057-saw-these-today-when-looking-for-dart-parts/

 

[fraso]

I am glad to read that you've got carburetor issues mostly sorted out.  If you would have had problems with getting a working 1bbl carb for your car, Joe's suggestion to use an aftermarket 4bbl carburetor is valid.

 

On 6/19/2017 at 11:51 AM, joe_padavano said:

To the OP's problem, given the difficulty in finding a suitable single barrel carb, you MIGHT want to consider an aftermarket intake and very small 4bbl.  I realize this is not the least expensive route, but probably the easiest.  The E-brock 500 CFM carb is about right (I've had one on my 215 cu in Olds V8 for the last seven years with no problems).  Offy sells this intake for the 225.

 

 

I have a 1965 Barracuda with a 225 since 1983.  I upgraded to a 9625 Carter AFB in 1987 and used it until 2004 when I upgraded to a M4MC Quadrajet.  Although the 625 CFM AFB is a bit oversized for my slant six, the main issue I had with it was the former owner completely removed the choke mechanism for drag racing.  Summer operation was OK but it wasn't fun to start in cold weather.

 

While it's true that new 4bbl carbs are not calibrated for slant sixes, Edelbrock 4bbl carbs are very easy to recalibrate.  Many people use the 390 CFM Holley on these engines but, never having worked on a Holley, I can't say how easy they are to tune.  I found that tuning my Quadrajet to be even easier than tuning the AFB.  Remember that a 4bbl carb with vacuum or air valve secondaries operates in 2bbl mode most of the time.

 

See Quadrajet Upgrade and Quadrajet Tuning.