Troubleshooting the Tuning of My 440

[firefighter3931]

Hi Mick,

As I said in the PM....it's now running leaner with the improved spark energy so the engine is definately going to want increased jetting. This is not uncommon when upgrading from a poor wire to a superior one. You've gone from 7000 ohms/ft to 250 ohms/ft so there is a dramatic increase in the amount of firepower igniting the air/fuel mixture 

I'm pretty sure those plugs are going to be clean as a whistle. 


Ron

[HeavyFuel]

Pulled #1 plug.   Very clean.  The prong is almost white in color.....just a hint of tan/gray.


I jetted up one size from OEM to 104 primary, the secondary was already up one size from OEM, so it got the next size of 095.


Hopefully the drive tonight will yield positive results.

[firefighter3931]

Sure sounds like it's lean. 

See what a difference the wires can make....black/fouling plugs to clean white/lean plugs with just an ignition wire swap 

Keep jetting up until you get a little tan on the porcelin and base of the plug. 



Ron

[HeavyFuel]

Installed a different ignition box.  Same as was spec'd for OEM  1972 Charger w/440.   Standard Motor Product-made in the USA!  Relocated it to inside the cabin from it's spot on the firewall directly behind the block.  This box replaced the 1992 orange MP box.

Went for a test drive last night....about 73*, windy.

Car ran great after warming up.   Took it out on the high way and got on it a little.    The temps stayed good during that time.

Got back into town and the temps started climbing....probably normal after pushing it kinda hard.  But when I got up to a light and stopped, the temp gauge kinda spiked quick up (like 1-2 seconds) to about 225, and then came back down again to about 210ish and hovered around there till I parked.

This overheating is a pain.  I didn't expect this to happen, the engine has always run in the 180ish range.

Pulled a few plugs this morning.   Some of the black around the base is leftover from when I cleaned them up from before.  What do you think?

The coil I have on now has a primary resistance of 1.3 to 1.5 ohms, and the former coil had .3 ohms.  Does that matter?

[firefighter3931]

It could be that the idle mixture is lean based on the fact that it now heats up sitting at  light idling. I would try richening up the idle circuit and see what happens. 

It was so rich before that the overabundance of fuel was keepin it cool and now you've gone the other direction.   

If you leave it idle in the driveway will the temps spike up ?



Ron

[HeavyFuel]

Jetted up to 107s in the primary, 095s in the secondary (both are two sizes above stock).  

Engine seemed to run pretty decent after warming up.

Cruised over to the fill 1/2 tank of gas (91, no ethanal) drove around town a little bit, mostly 25-55 mph.   Temps stayed decent for a while, then slowly climbed into the 215* zone.  Didn't really matter if I was moving fast or slow or stopped.

Tried to richen the idle circuit, all that did was make it idle like crap.....still got hot.

Now I'm thinking bad thermostat?

And it seems like she picked up a ping again now, just past the off idle hesitation point, if I get on it a little.  Have yet to floor the throttle since firing up the motor last year, and putting on about 2000 miles....can't ditch the ping.  Suppose I could back down the initial from 14 to about 10, but then the total will only be about 30.     Would tightening up the vacuum advance pull some timing out when the motor looses vacuum.....which is about the time I get ping now?      


This car drives fine if I want to just 'grampa' around.....but it's just embarrassing otherwise.  My 1998 Grand Caravan 3.8L can beat it 0-60 mph.

 Suppose a new carb and distro are in my future.   My main squeeze is gonna punch me.  

[HeavyFuel]

Tuned the carb a little bit.  Richened the idle mixture, the screws (the AVS ones you aren't supposed to mess with) are out about 3.5 turns....quite a bit.  The center idle screw is all the way in.    That where it shows the best vacuum.  Set the idle at 800 rpm.

Out of shear frustration, and, because I've been dying to try this.....switched the vacuum advance from ported to manifold.      

Initial =          13*
Vacuum pot = 18*
Mechanical =   20*
                     51* total

I set my adjustable timing light up and adjusted the pot until the distro (with advance hooked up) was bringing in 31* at 800 rpm.  That way I was sure that the vac was fully advanced, and it wouldn't over time when the mech advance came in.

Took it for an easy test drive around the block.  Hmmmm.  Not bad running.  Smooth.  Temps at about 185-ish.  

Went out on some faster roads.  Temps rock solid.  Off idle hesitation is almost none existant.   Engine seems to be running really nice.  


Got on it a little bit....no detonation.  Getting back home, the engine seemed to be running too smooth, and fast, like the idle had crept up.  After checking, it's still at 800 rpm.  Just that smooth.

Hmmm. engine runs cooler now, and better than it has ever.  Off idle stumble seems to be all but gone.  

Summary of what's been changed in the last month:

1. CH4B replaced the OEM cast iron intake.
2. Punched a few holes in the valley pan block-off for the intake crossover.
3. Manual choke installed.
4. Cleaned plugs.
5. OEM coil (standard motor company) replaced Accel Super Stocker.
6. Firecore 7mm 250 plug wires replaced 7k/foot dated coded wires.
7. OEM ignition box (Standard Motor) replaced 20 year old orange box, relocated to inside the cabin.
8. OEM size metering rods coupled with jets that are two sizes bigger.
9. Drained out about a liter of coolant, refilled with water plus Water Wetter.
10. Changed vacuum advance source from ported to manifold, adjusted timing.
11. Lengthend the accel pump shot.

When you throw the book at it like I did, it's hard to know what combination is making things better...or worse.  But a guy's gotta do something, so you just start trying stuff.

Tonight feels like a step in the right direction.  


                     

[firefighter3931]

It sounds like the changes worked out well 

The change from ported to manifold vacuum means that it wanted a lot more timing than you had in it before. 

Retarded timing coupled with a slow advance curve will definately create an overheating condition. If it runs good and stays cool w/o detonation you can just leave it that way.


Ron

[HeavyFuel]

Turns out the manifold vacuum switch didn't fix the overheating.    

So why not check the obvious?  The thermostat.    

Ordered up a Gates 180* and tested it side by side against the one I had in.  Gee, the old one didn't open all the way, probably like 3/4.    

Summary this round:
Installed new 180* stat, complete with 1/8 inch drilled air hole.
Reduced the initial to 12*  (working on slight pinging problem at medium throttle)
Reduced vacuum advance to 15*  (ditto)
Switched the vacuum advance source back to ported.
Changed metering rods to one size smaller...to go fatter.  (I did the old 'hold your hands over the carb while it's running', and the engine increased speed and vacuum, so it must need MORE fuel    )

Took her out tonight for a test drive.  Temps were cool as the other side of the pillow.  Straight up 180*.         Seemed to run pretty well.  No ping, but I didn't push it very hard.  Will probably look at the advance curve....again.

[firefighter3931]

  (I did the old 'hold your hands over the carb while it's running', and the engine increased speed and vacuum, so it must need MORE fuel    )

Usually, when you block the air inlet the engine will die unless there is a vacuum leak. 

I'm starting to think your detonation issues are a lean condition. 

Lean will also make the engine run hot 


Ron

[HeavyFuel]

Swapped out the springs in the dizzy....thought that the mech advance might be coming in too soon.  

Put in a medium and a lite (from what I can tell).

Set the initial at 12*.....800 rpm.

With the adjustable light, I'm reading 24* at 1500 rpm......mechanical starts coming in almost immediately after idle.

Total advance....32*, all in by 2500 rpm.


Do you think that the mechanical is coming it too soon?  I've read that the mech should just be starting to happen at 1500.

[firefighter3931]

As long as it doesn't ping under heavy load you are good to go 


Ron