[Chrysler300] Fueling the discussion

Our ’55 C-300 came from the factory with two thermally-actuated chokes. They were actuated by a stream of air heated in a tube in the RH exhaust manifold and bled into the carbs through the choke body. The tubes were wrapped with (gasp) asbestos to help keep the air hot. The hot air would then heat the coil springs in the choke bodies and open the chokes. I’m not sure, but I believe the hot air flow continues into the carb continuously.

For whatever reason, the original owner in southern Colorado had the automatic chokes removed and replaced with two manual chokes with knobs under the dash. The installation looks very professional, apparently with Carter parts. I must admit that I appreciate the absolute control over the choke process. I have an electric fuel pump feeding the mechanical fuel pump and allow it to operate until a change in pitch indicates the carb bowls are full. Then, just a little choke, a pump or two and a nice quick start. (Yeah, I know, there is a risk of pumping gasoline into the crankcase if the mechanical pump diaphragm fails. There is a heat-riser valve on the RHS exhaust manifold that forces RHS exhaust to the LHS exhaust pipe via the intake manifold. This quickly provides carb heat and enables the chokes to be manually pushed open. This works fine in mild to hot CA and should also work in IA this time of year.

Additionally, both carbs on our ’55 are hard linked together and feed the engine simultaneously. Secondaries are flow/velocity controlled. I believe the ’56 300B cars were also hard linked and that later hemi’s were connected by progressive linkage that did not open up the front carb until ¾ throttle or more. Perhaps that was for economy reasons. I get better mileage towing our ’55 on a trailer behind our Hemi-rango than when driving it.

For those few conservative and cautious drivers that bought cars having one or two four-barrel carbs, the unused bowls and carbs could gum up with the residue from evaporated leaded gasoline. Along with other gearhead teens, I was always willing to take grandpa’s Chrysler out and blow the cobwebs out of it with WOT runs. One of my buddies’ granny had a Cad Eldorado with dual quads and we were ALWAYS willing to exercise that beast. I recall the dealer once replaced the carbs after her complaints of rough idling and operation in Des Moines—on her dime. Backfiring and black smoke might emit as the junk gas was displaced with good stuff and the internal passages of the front carb were partially opened. Often, carb cleaner had to be poured into the intake while racing the engine to dissolve the gunk—the blue black exhaust showed the results of the cleansing. Gasoline in the ‘50’s also had its problems with deposits. Big oil then started adding detergents such as Shell’s TCP (tri-cresyl phosphate, not tomcatpee) that helped clean the carbs and maybe even the intake valves and combustion chambers.

C300K’ly,

Rich Barber

Brentwood, CA (Got maybe ¼” of rain last night—so much for the bloody monsoon season)

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of John Nowosacki
Sent: Thursday, January 30, 2014 8:53 AM
To: kmaniak@xxxxxxx
Cc: John Grady; Michael Moore; list server
Subject: Re: [Chrysler300] Manifolds and carbs

I believe the 'one choke for two carbs' on inline setups also applies to the 55-58 Hemi engines as well.

On Thu, Jan 30, 2014 at 11:18 AM, <kmaniak@xxxxxxx> wrote:

John:

With all due respect, I feel compelled to offer a few clarifications regarding the manifold and carburetor set ups on the letter series Chryslers.

The in-line twin carburetor set up used on the E and H was designed in such a manner that the front two barrels of the rear carburetor was the primary fuel supply to the entire engine at start up and low speed operation. Therefore, there was need for only one choke, located on the primary barrels of the rear carburetor as Mike describes. The rear carburetor secondary barrels, and well as the front carburetor barrels, only opened after the primary barrels were at least one-third to one-half open. Both carburetors fed all eight cylinders simultaneously.

The cross ram engines differed from the in-line engines in that each carburetor only fed four cylinders. At start up and low speed operation, the primary barrels of both carburetors were required to operate, with each carburetor feeding only four cylinders. As such, two chokes were required, one for each carburetor. Given that the '60 & '61 cross rams had automatic choke pull offs, and each worked independently of the other, I can see how a lack of synchronization could really mess up cold start engine performance and drivability. And I agree that the manual choke set up used on the J and ram K provided synchronization. The manual choke was also cheaper to produce, and I think Chrysler was pushing "cheaper" when building the J and ram K.

Now I need to touch for a moment the subject of the "exhaust heat riser valve". To be clear, this special valve was a thermostatically operated butterfly valve installed just before the exhaust flange on the passenger side "log style" exhaust manifold. The purpose of this valve was to temporarily restrict exhaust flow from the right side of the engine and force a portion of the exhaust gases from the right side of the engine through the right cylinder head, then through the base of the one piece intake manifold, then out through the left head. This allowed the exhaust to quickly heat the intake manifold for quicker warm up and better cold start drivability. On engines with intake manifolds and carburetors installed between the cylinder heads, only one "exhaust heat riser valve" was installed on the right exhaust manifold. The cross ram engines did not have carburetors mounted between the heads. The cross ram manifolds included blocker plates that capped off the upper center exhaust ports in each cylinder head. As a result, exhaust gases did not flow from head to head on a cross ram engine. Therefore, no "exhaust heat riser valve" was required or installed on the ram engines. Each ram manifold receives exhaust flow from the respective exhaust manifold below it on a continuous basis.

Hopefully we are all on "one page" now. I welcome any comments or differing opinions.

Chris the K MANIAC

-----Original Message-----
From: John Grady <jkg@xxxxxxxxxxxxxxxxx>
To: 'Michael Moore' <mmoore8425@xxxxxxx>
Cc: Chrysler300 <Chrysler300@xxxxxxxxxxxxxxx>
Sent: Wed, Jan 29, 2014 1:20 pm
Subject: RE: [Chrysler300] Manifolds and carbs

Only one carb was connected to your setup? So you started on 4 cylinders..? The J setup manual choke split in two if I remember right , made both carbs do exactly the same thing.. What you want ...

They should have had one choke control and cross link the carb fast idle and choke mechanically. Not sure why they did not do that. Would have cost less and worked right.. What they do matters less ----than they do it together.

Exhaust heat riser valves both have to be in sync too. Or you get loping idle , stalls when you push D on cold days, equals starting it 5-6 times . If you had manual choke on both, (J) , it just let you raise idle high enough manually when cold to cover up all this. But still harsh D engagement was the norm. Tests that fine front U joint on 60 -61, too!!. “Clang” !!---J had a little looser converter, not as harsh maybe.

And they are a bear to start if they get badly flooded , not sure why..My .02: = maybe gas sits in a deep puddle at bottom of ram under carb till it is good and ready to evaporate out, (no other way out) but a squirt of ether and away you go. On regular manifold, that gas would run down into ports.

Despite working on these on and off for what 50 years now, I admit to lots of suffering along the way. Can do in minutes what used to baffle me for a day. One key thing I found is that many, if not most of the carbs have destroyed adjusting needles by now , due to all the playing with them..if you see a ring or step worn circumferentially around the needle, no question -- it is junk. Cannot be adjusted right. That ring comes from “golden screwdriver “ and going too tight into hole, prior to “backing out 1.5 turns” . I found new Edelbrock needles (spare parts from them) are beefier and fit and work even with possible damage in carb body..taper is slightly different. .# 1 thing you can do about frustrating drifty funky idle setup. ..that changes by itself every time you look at it. I mistakenly junked several “untuneable “ ‘defective” carbs before knowing that, After careful rebuilds, still the idle problem remained .....

From: Michael Moore [mailto:mmoore8425@xxxxxxx]
Sent: Wednesday, January 29, 2014 9:02 AM
To: John Grady
Cc: kmaniak@xxxxxxx; mark6268@xxxxxxxxxxxxx; chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Manifolds and carbs

John,

I have owned my 300H since 1965 or so. When I got my car, it had a very nnicely installed manual choke. It was a very clean installation, which I thought was factory for a while, using one of the unused round knobs beneath the dome of the instrument panel. The unused knob had a set screw and was used to connect to a choke wire which went to the rear carb. It was actually, I thought, much more useful than my curent electric stove choke.

I only removed it because it would gradually creep into the choke position as the engine vibrated, so I frequently had to push the choke back in. Sometimes, on a long trip, I woujld only notice it when I realized the engine wasn't running right and would find the choke fully engaged.

Otherwise, I thought the car started easier as I could momentarily choke the crap out of it if it was cold and as soon as it fired start coming off of choke.

Mike Moore

300H

On Jan 29, 2014, at 4:21 AM, John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

Another aspect of this was very poor choke pull off on ram cars ; one side pulls off before other even today . Certain types of cutomers would not deal with this in 60 , 61. I was there , one person i know had rams pulled off 383 61 plymouth wagon over terrible idle /cold start /warmup stalling isuues in Boston ... New car .

J and K (?) had manual chokes to ensure syncrony . Ram cars are cut a lot of slack today , but remembet at meet in maine it took 5 club membets half an hour to start a perfect flooded F
N
On Jan 28, 2014, at 11:00 PM, kmaniak@xxxxxxx wrote:

Hi Ron and All:

The following is my "two cents" on the subject based on years of observation and intuitive theory.

The 1955 through 1958 cars were equipped with A-block hemi's. The high performance intakes for these engines were in-line 2 x 4 barrels.

1959 saw the introduction of the new B-block and RB-block engines equipped with wedge heads. Immediately the in-line 2 x 4 barrels intakes were installed on the E and other high performance MoPars. And in Chrysler tradition, they ordered a large lot of in-line manifolds to use over the next several years.

Meanwhile, the engineers at Chrysler were experimenting and perfecting the performance potential of ram induction. For the 1960 model year, Chrysler introduced their first version of ram induction by unveiling the crossram induction system as standard in the 300-F and optional in Dodge, DeSoto, and Plymouth, on both B-block and RB-block configurations. The crossram manifolds came in two designs, the 30-inch long ram manifold, which developed maximum torque at 2800 rpm on the 380 horsepower engines and the 15-inch short ram manifold, which developed maximum torque at 3600 rpm on the 400 horsepower engines. Again, following tradition, Chrysler ordered production of large lots of both style manifolds to use over the next several years. My guess is up to 3000 pairs of long ram manifolds and up to 1000 pairs of short ram manifolds were produced during 1959 & 1960. The power brake system used on the 300-F and 300-G, was a system using a f irewall mounted master cylinder and a bellows type power booster mounted on the firewall above the master cylinder. This style of power brake did not create a clearance issue with the ram manifolds.

1961 saw a major shake up in corporate management. The biggest change from management was the end of large lot parts production and stockpiling. Chrysler used up the current inventory of long ram manifolds with 300-G and other Dodge and Plymouth engine options. The large stockpile of of short ram manifolds still remained since these were part of an option that was not too popular. Also, a stockpile of in-line manifolds still remained from 1959.

Let me digress for a moment. Have you ever wondered why the side trim on 300-C's through 300-G's looked the same? That's because it was all the same. Most likely it was all manufactured at one time in a huge lot to be used up over the course of several years. New Chrysler management moved to use up all the excess inventory of trim by creating and building the 1962 Chrysler 300 (aka sport). Another new feature on the Chryslers in 1962 was the used of the firewall mounted power brake booster with integral master cylinder, which was most likely cheaper to produce than the older power brake systems. Since all the long ram manifolds were used up and there was a clearance issue with the new power brake boosters, Chrysler installed the in-line 2 x 4 barrel manifolds on the 300-H and even built a few sport 300's with this engine as a way of using up the old inventory of in-line manifolds. The 400 hp short ram engine was offered as a deal er installed option only in 1962, but demand was very low. A large stock of short ram manifolds continued to collect dust on the parts shelves during 1962, approximately 727 pairs.

In order to use up the last of the short ram manifolds, Chrysler built a special 390 hp engine with reduced compression ratio, solid lifters, special cast iron headers with exhaust fed carburetor heat. (Note, the 400 hp short ram engines from 1960 through 1962 used coolant carburetor heat). This engine was the only engine available in the newly redesigned 300-J. Given the clearance problem with the firewall mounted power brake booster and the ram tubes, a special remote booster was used with a firewall mounted master cylinder. Chrysler may have hoped to use up all the 390 hp engines in 1963, but alas, only 400 300-J's were built, reducing the carry over back stock of short ram manifolds to 327 pairs.

To capitalize on the letter series reputation and guarantee using up all the short ram manifolds, Chrysler offered the 300-K with a standard single 4-barrel engine and offered the ram engine as a option. Not only did Chrysler finally used up all the short ram manifolds, I spoke with former Chrysler dealer employees from 1964 who swear that their dealers received one or more 300-K's at the end of the model year with factory equipped in-line 2 x 4 barrels.

Hopefully this gives everyone a glimpse at why I think things were the way they were with regards to the letter cars.

Chris the K MANIAC
-----Original Message-----
From: Ronald Kurtz <mark6268@xxxxxxxxxxxxx>
To: chrysler300 <chrysler300@xxxxxxxxxxxxxxx>
Sent: Tue, Jan 28, 2014 4:42 pm
Subject: [Chrysler300] Manifolds and carbs

Hello, everyone:

I've been following the thread on the '62 Chrysler 300 (H?) and now wonder why C300, B, C, D and E had a 2x4 bbl. intake manifold and the F, G, J and K (option) had ram induction. What was Chrysler's logic for this on-again and off-again aspiration? Just curious.

By the way, I will have a '64 K 360 HP engine in running condition complete with correct carb and air cleaner up for sale this Spring. Asking $500. Buyer picks up. Please advise if interested.

Best,
Ron Kurtz
E #292

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