FYI FORD - MustangSteve's Ford Mustang Forum
The Internet's Most Knowledgeable Classic Mustang Information
IF YOU HAVE A QUESTION ABOUT CLASSIC FORD MUSTANGS, YOU HAVE COME TO THE RIGHT PLACE!
MustangSteve has over 30 years of Mustang experience, having owned 30 of them and restored several others. With the help of other Mustangers, this site is dedicated to helping anyone wanting to restore or modify their Mustang.... THERE ARE NO DUMB QUESTIONS!!!!!
Visit MustangSteve's web site to view some of my work and find details for:
FYIFORD Contributors' PICTURES - Power Brake Retrofit Kits for 65-66 Stangs - Classic Mustang FAQ's by MustangSteve - How to wire in a Duraspark Ignition - Mustang Ride Height Pictures and Descriptions - Steel Bushings to fit Granada Spindles to Mustang Tie Rods - Visit my EBAY store MustangSteve Performance - How to Install Granada Disc Brakes MustangSteve's Disc Brake Swap Page - FYIFORD Acronyms for guide to all the acronyms used on this page - FYIFORD Important information and upcoming events

You are not logged in. Would you like to login or register?

10/25/2018 8:26 AM  #1


carburation on 4100

Hello folks , i am trying to make it lean due to dark exaust and a lot of smell driving .
Despite of smell the driving was good without any gap on acceleration and strange feelings .
The sparks are dark  all around and only the center is clean. 
the jets was 47  and 56  .
Now i recived some different jets to try and this is my first try  44  and 54. 
jets screw on 2  1/2  back from complete close.
Now  dark smoke is away and smell is less than before but running is not the same .
Acceleration is less linear and has some little gap all over the rpm
This gap feelings is also when i try to stay at same rpm for a while and sometime random , gap.
I don't know what it could be , seems that sometimes is missing one plug or a misfire  .
Carbs do not pop and float level are ok like gas pump pressure.
Does it possible that from 47 to 44 i have make a jump too big  ? 

Thanks for any suggestion

 

10/25/2018 11:32 AM  #2


Re: carburation on 4100

When cruising at a constant speed does it surge?  I think the "misfire" you are getting could be a surge.  Surging means its too lean.  Problems in transition (accelerating) can also be caused by being too lean.

Are those jets #s?  Jets are referenced by numbers and diameter.  Often its not a linear correlation.  I would look for a chart the shows the # and the diameter to aid in tuning. 

 

10/25/2018 12:04 PM  #3


Re: carburation on 4100

TKOPerformance wrote:

When cruising at a constant speed does it surge?  I think the "misfire" you are getting could be a surge.  Surging means its too lean.  Problems in transition (accelerating) can also be caused by being too lean.

Are those jets #s?  Jets are referenced by numbers and diameter.  Often its not a linear correlation.  I would look for a chart the shows the # and the diameter to aid in tuning. 

Not seems at constant speed , but fore sure more advisable on acceleration  . 
If is too lean i need to rise , but i will get again dark exaust and smell  , do you agree ? 
I will double check jets , but mike 's carburator  is sharp and clear about size . 
mine are the big  old type ford (# witten on side )
(not holley size).

Thanks

     Thread Starter
 

10/25/2018 1:51 PM  #4


Re: carburation on 4100

Can you advance the timing some....and get back some power? ( Advance timing sometimes mimics leaning carb soooo?!)   Timing adjustments can make a HUGE difference in performance. Many times advancing the time will "lessen/eliminate" the smelly exhaust....jus say'in!
6sally6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

10/26/2018 5:29 AM  #5


Re: carburation on 4100

Black smoke means its WAY to rich.  You can go richer without smoke.

The smell should not be like raw gas, but you are always going to have some smell from any vehicle with a carb.  Carbs are not a sealed system, so there's always a smell from the bowl vents.  BUT, it should not smell like you have a bucket of gas sitting open in your garage either.  That IS a sign its too rich.

If there's no surge at constant speed, then its not too lean.  If it stumbles when you first start to accelerate it could mean you need to change the arm position on the accelerator pump for a bigger shot of fuel.

I would give 6sally 6's idea about timing a shot too.  Timing does make a huge difference.  With too little advance there isn't enough time for the engine to burn all the fuel.  Whats the timing set at now?

 

10/26/2018 7:13 AM  #6


Re: carburation on 4100

Ok first try was little lean . Now i put a 46  just 1 point less from starting point . 
Is not smoking but smell is still high . Make a ride and is going good . no esitation or surge . 
Now i cant' answer about timing advance until i recive my new strobe light , I have touched distributor a little during trial .
just a dumb thing :   clockwise is advance     unclockwise is retard    correct ?  .
the acceleration arm have 4 dots vertical  .  i moved from second to first spot  . that means quick as possible   corrext ? 

Thanks !

     Thread Starter
 

10/26/2018 11:34 AM  #7


Re: carburation on 4100

Yes, clockwise is advance, counterclockwise is retard.  The rotor in a Ford spins counterclockwise.  Total opposite of a Chevy BTW. 

 

10/27/2018 5:32 AM  #8


Re: carburation on 4100

I have my vacuum advance(the hose from the distributor) connected at the manifold not the carburetor.

 

10/27/2018 6:50 AM  #9


Re: carburation on 4100

daily driver wrote:

I have my vacuum advance(the hose from the distributor) connected at the manifold not the carburetor.

mine is connected to carb.


 

     Thread Starter
 

10/27/2018 8:15 AM  #10


Re: carburation on 4100

Depending on where on the carb it is connected it could be connected to manifold.  They key whether the source is below (manifold) or above (carb) the throttle blades.

It determines when the vacuum advance has effect.  Drawing off manifold vacuum it effects timing at idle.  Drawing off the carb it effects timing everywhere except idle.

I've always tried both and just stuck to whatever created the best idle. 

 

Board footera


REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.