[Chrysler300] 375 Troubled horses.

[Ulf Larsson <ulf.larsson@xxxxxxxxxxxx>]

Hi group,

Some thoughts to possibly help out with the dual carb problem (For those with some time to spare for to read) .

First thing first;  Yes,  although the car is older than me, I´m pretty sure it DID work good to begin with.  I know for sure it does run good after a stock carb re-build if/when made properly.   No need to go aftermarket, AFB, Edelbrock or whatever.

This is even on modern fuel (5% alcohol). Just make sure to drive it a lot. When storing two things seems to happen;  1;st it will be hard to start. The juice in the fuel seems to ventilate away through the carbs in just a few days time and one need to crank (all stock set up with a stock mech fuel pump/ me, actually modern small block stock mech fuel pump and with the HotHeads adapter for mounting) extra or fill a spill of fuel from a can immy before start in the front carb.  If running within hours or less than 3 days of storage it´s easier. Turn the key, Once on the accelerator to squirt some fuel and activate the choke,  Push the button, and Vrooom it goes. IMMY.  Quality stuff although 54 years old, but yes, I admit, I run it with one of Mr Lazenbys modern gizmos, the Pertronix, from getting tired climbing on top of everything trying to readjust those dual points at the back of the engine where there is so little room.  Pertronix with a Pertonix coils is the way to go.
2;ndly it´s the gunk that builds in the fuel from storage if with alcohol. Will be even worse when they turn for +10% involvment.  Drive more seems to be the only answere to that, and a good fuel filter, prior to the pump, and probably change start of season.

So further on: Yes,  I do have a 300C.  Yes, I did buy carbs while my car came with a modern Edelbrock set up when I bought it.  Found 3 pairs (said to be correct WCFBs) in the us over the years. 1 pair said to be professionally rebuilt, and two pairs looked like someone left them in the fire. Started of with the smashing good looking, expensive,  re-built ones. They are now still on my work bench.   No nothing but the brass tags (WCFB 2534S and WCF 2535S), top lids and the bottom in cast iron for the butterflies were correct. A ll the rest was MIX UP, wrong, no good for use. Nice looking but a fraud!

Had to concentrate on the other two pairs. All butterflies were stuck but one.  To cut a long story short.  It works. Be careful, do your home work, set levels properly and it will work, beautifully.  I have run my car for more than 5 years using what I did restore by myself.  Careful to blow all passages clean though, etc.  With one carb I did have problems with this and came from glass media blasting for cleaning the mid part of the housing. Pref go chem cleaning before the yellow/greenish replate perhaps.

Check carefully for the following (the parts are marked!);

Meetering rods to be marked                           75-1263 (or 75-1372)
Primary jets                                                                120-163
Secundary Jets                                                         120-226
Long Jets front                                                         11-306S
Long Jets rear                                                           11-311S

Meetering rods from -58 set up can probably also be used.  Those are 75-1160, 75-1180, 75-1181.


Check float bowl needles and seats. Modern needles are with soft (teflon?) tips and must be with no damage.  Modern re-build kits have brass seats for the incoming fuel needles that are (universal) larger in size than stock for the 300 C.  Better use stock if no damage is visiable.

Check floats.  They must float!   They must not bind towards the wall of the carb housing. Distance here is slim but adjust is easy. Just carefully bend a little   More important than anything (but that floats do float and that they are not heavy and filled with gas) ;  Adjust of Float levels.  Both upper and lower level (iow distance to lid when holding the lid correct way but also upside down.  Both these measures are important as is needle tips in good order. I don´t recall actual dims by hart but I used what is given in litterature (mid value while three with slight difference were found at the time). Easily done with some careful bending but bend, try measure, bend again etc until correct values in both directions, for all 4 pairs of floats.

Other settings;  To my experiance of less importance other than if racing, and the risk it goes too lean. Go by the book with the settings (Carter WCFB  manual or -58 300 Supplement for the repair manual) and you´ll come out fine.  I tune for extra rich (1/4 turn extra for mixture screws , counter clockwise, at the bottom of each carb, but that´s just me afraid to burn exhaust valves on a too lean mix) when I do the dragracing excercise. the fat one adjuster on the side of the carb on secondary butterflies I keep almost shut. To open slightly on wear (and dirt build up over time)


Check that the small round lid on the cover over acc pump is indeed slightly OPEN at rest.  Check that you have a good squirt when activating the acc pumps. (Both carbs)
Can one run with one carb only?   Indeed, at moderate speed/loads and especially if need for troubleshooting at idle condition.  Pls compare with the original set up:

A start is on extra rich from chocke from the rear carb, and extra high idle.  When varm up the chocke shut off and the drive is on the rear carb only (for chickens like me), and with the idle contribution adjusted on the front carb.  (the rear shall go fully close at no pedal and engine idle on front carb only. If running trouble shoot with only rear carb you´d have to set an idle for this carb also)  The car actually runs like with a miniatyr 2bbl (Ports are small. Just turn the carb upside down and look).  When the throttle is pressed, and the FUN begins it will (progressive stock set up) Go full open on small front butterflies on the rear carb, than also the secondary (rear) butterflies on the rear carb and quickly also the small front butterflies on the front carb and finally, Foot to the floor, also the secondary  on the front carb too.  A very inexpensive way to possibly get more  boost to your ride;  Check that this is actually happening when flooring.  Adjust is only time and for free if you do it yourself.  I had to.  Angle on pedal towards floor was wrong (300 supplement again for ref)  and same with linkage.  Friends over here found themselves in the very same situation. More horsepower and for free with some minor adjustments found neccessary.

Finally;  If you have an extra electric fuel pump;  Make sure the float needle valves can hold back the pressure or arrange for a return passage for excessive fuel like on any modern car with fuel injection.

Good luck and good fun.

Wish you all a good weekend.  It´s Chrysler 300 time again. I´m going to pack up the bags (and go dragracing)  this weekend again. As spectator this time but the ride to there will be nice in the BigBlackBrute (CTG 666) and I know that one of the participants will race his, also BLACK, Chrysler 300C (All glassfibre body, Pro Mod tube chassie) with an all race  +1000" engine.  First run with the new set up so I wish Mr Alvin a good hunt.
Just go for it.

Best regards,
Ulf, Sweden


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