440 - Initial timing and advance clarification please?

[Nickrc3]

Gentlemen,
               I'm getting back into the Mopar hobby after a 28 year hiatus and request clarification of what I recently observed in my attempt to tune the 440 today in my 69' Charger R/T.



Outside of the 284 duration/484 lift Mopar purple camshaft, and a rebuild back in 1998 (.030 over), the number-matching engine is stock and mechanical sound. (I did disassemble the engine last year to check wear patterns and basically reseal/re-gasket everything).
She's equipped with the original Carter AVS carb, intake and HP exhaust manifolds, and a Mopar electronic ignition distributor w/ orange box. 727 TorqueFlite w/ shift kit, 323 SureGrip.

Though a cruiser vehicle, I was never really pleased with the straight-line performance from a dead stop. The engine  would occasionally cough and sputter upon hard acceleration, and sometimes 'break-up' at 4500-5000 RPM's.

I installed a vacuum gauge @ manifold port and a timing light (w/ RPM indicator) in an attempt to adjust the carb air/fuel mixture screws for maximum RPM and check timing. I received a steady 15" of vacuum @ idle speed of 765 RPM's, but the idle-mixture screws had a huge range of adjustment. Is this due to the camshaft specifications?

Timing - I originally had 12 degrees BTDC w/ vacuum advance canister line pulled and plugged. I failed to record the total timing at this time.
I then bumped the initial timing to 16 degrees BTDC, which gave me a smoother idle. However, upon measuring the advanced total timing (vacuum advance line reconnected), it appears I have 47 degrees TOTAL, and it comes in at only 1600 RPM. From what I've read here on DodgeCharger.com, that 47 degrees appears to be quite a bit. Outside of detonation, what issues may I encountered with this high and possibly premature advance setting?

What total timing number should I be trying to achieve, and at what RPM? 38- 40 degrees?
How can I map the advance curve and perform necessary changes? Would I first adjust the vacuum canister (w/ allen wrench,counterclockwise), then utilize heavier distributor springs?

I did drive the vehicle to a secluded area and she performed better - spinning the wheels in Drive through 1st and 2nd from a stop. Just a slight sputter.


Thanks for your replies.

[firefighter3931]

Hi Nick, that's a nice Charger you have there 

The 284 cam is wrong for the rest of your build and is part of the reason you're having tuning issues. The fuel curve on your stock carb is not agressive enough for that cam. The 284 really needs a double pumper style carb to work best. It also needs a looser converter (3000 stall) and deep(er) gears (3.91-4.10) to operate efficiently. Personally, i would look at another cam if you want to keep the stock carb/tq converter/3.23 gears. 

The second issue is your distributor. It has 31* of mechanical advance and that is too much as you've discovered. That, coupled with the cam you're using is creating problems. Big cams like lots of spark lead at idle so when you bump up the initial timing to where the engine is happy....your total timing is off the chart.   

Ideally, you want as much initial timing that the engine will tolerate and no more than 36* total all in by 2500-2800 rpm for a typical street build. The speed of the timing curve is determined by the springs on your advance weights inside the distributor. I've found that one light spring & one medium spring achieves the desired results. 

What you need is a distributor that has an adjustment for the mechanical advance so you can custom tailor your timing curve. 


Ron

[Nickrc3]

Ron,
Thanks for your reply and all your valuable information provided to the members of this Forum. You and others make this site the best on the Web!

Yes, I learned from your earlier posts that particular Mopar 'Purple Shaft' camshaft is an obsolete grind and really not recommended anymore. I believe you favor the Lucati 'Voodoo' series cams. Which one would you recommend in my application? I desire a relatively tame idle, and a low to mid RPM performance range - say the 303?
If I decide on a cam change, I would like to NOT remove the cylinder heads. Would I be O.K. with the valve-piston clearance using the 303 cam?
Degreeing a cam - I did this procedure back in 82', but forgot exactly how it was performed and why it was necessary. I recall adding a aluminum button to the camshaft dowel pin which offset the camshaft timing gear. Can you briefly explain the process and the term 'install @ centerline -110*
Hydraulic Lifters - are the variable-duration type advantageous? I used 'Rhodes' back in the day. Simply order a cam kit and use the included lifters?

Lastly, re-curving the advance characteristics within the distributor - you mentioned 31*. Is this the maximum the Mopar distributor will produce without performing some machining or modification inside the distributor?  How can I reduce the total 47* and still achieve that 16* initial @ idle? The tension of advance springs control the physical movement of the weights which affect the rate of advance. How can they limit the maximum amount , or they cannot?

Thanks again.

[firefighter3931]

Hi Nick,

Yes, the 303 would be an excellent choice for your engine and combination of stall/gearing. Smoother idle and much better throttle response. Your 284 doesn't really come alive until 3000 rpm so with a stock converter that stalls at 1800-2000 you have a big flat spot where the engine just lugs until it hits the sweet spot.

The 303 has a lower powerband so it will hit hard right where your converter stalls at.  

Degreeing the cam is done with a dial indicator, degree wheel and using a piston stop to establish TDC. It can be done with the heads on the engine, no problem. The installed centerline is where the manufacturer wants you to set the intake centerline. The 303 is a 110* LSA grind and Lunati recommends an installed centerline of 106* which is 4* of advance (cam timing)

It's important to degree them in because sometimes there can be a machining error with either the cam or the timing set. If the cam timing is retarded it will kill performance.  

Here's a good tutorial from Comp Cams on degreeing : http://www.compcams.com/Technical/Instructions/Files/145.pdf

http://www.moparmusclemagazine.com/techarticles/engine/mopp_1211_degreeing_a_camshaft/lope_separation.html

As for the distributor ; there are ways to modify a stock distributor to limit mechanical advance. This involves disassembly and welding up the advance plate.

Here's a good tutorial on that procedure :
http://www.moparmusclemagazine.com/techarticles/engine/mopp_0301_mopar_electronic_ignition_system/

If you don't feel like going through all that baloney ; then there's the option of purchasing a new updated distributor with an adjustable advance mechanism. The new stuff is pretty nice because there is infinte adjustability with the advance mechanism....basicly you have the ability to adjust in 1* increments. Welding up the slots requires disassembly, welding, reassembly and then you're stuck with a specific limit on the mechanical advance. Should you want to change it....the whole procedure has to be repeated. Years ago, long before the adjustable advance mechanisms became available, this is what we had to do.  

Just some stuff for you to chew on....for now  


Ron


Ps. Here's a pic of our new Firecore distributor and coil ; billet aluminum housing and plug n play with the stock wiring harness and ECU 

[Nickrc3]

Great advice Ron! Just a couple more questions if I may... 

          Can I continue with the stock valve springs with the '303' cam?

          Welding the slots to reduce the total advance capability: T

[Nickrc3]

I didn't get to finish my other question regarding welding the distributor advance slots to reduce the total advance movement. This appears to be a hit or miss process of welding and grinding to achieve the desired total advance? I doubt any slot length measurements exist on obtaining a 38* total? Can I not achieve that 38* degrees total by just using a heavier (or doubling) advance spring, which essentially limits the advance cam movement?

Thanks again.

[firefighter3931]

Great advice Ron! Just a couple more questions if I may... 

Can I continue with the stock valve springs with the '303' cam?

It depends on the specs of the current springs. The 303 is not overly agressive but it does require something better than stock, both in terms of lift/coilbind & spring rate.

The Comp Cams #911 valve spring is perfect and drops right on the factory head and uses the stock retainers/valvelocks. It has plenty of coilbind room for the 303 and the right springrate as long as they are installed at the correct height.

If your (current) springs have 125lbs on the seat and 325lbs open and coilbind at .550 valve lift (or more) they will work. If in doubt ; the 911 is the default spring of choice. 


Ron

[firefighter3931]

I didn't get to finish my other question regarding welding the distributor advance slots to reduce the total advance movement. This appears to be a hit or miss process of welding and grinding to achieve the desired total advance? I doubt any slot length measurements exist on obtaining a 38* total? Can I not achieve that 38* degrees total by just using a heavier (or doubling) advance spring, which essentially limits the advance cam movement?

Thanks again.

What you're trying to do is limit the mechanical advance, after you've determined the best initial timing setting. Total advance is a combination of base timing + mechanical timing.

For example ; your engine wants 16* at idle and you need 36* total. That means you have to dial in the distributor to deliver 20* of mechanical advance. With the older non-adjustable distributors this means the aformentioned modifications (diassembly/welding/filing/reassembly etc...)

There is a slot dimension spec that corresponds to specific degrees of advance. The problem with that approach is it's time consuming to re-adjust your mechanical advance should you wish to alter the base timing. 

The heavier springs won't stop the distributor from advancing unless the weights are at the end of their travel. The springs just determine how fast (or slow) the distributor will achieve full mechanical advance. The heavier spring will slow down the timing curve but it won't stop it completely.

Using yours as an example : You have 16* initial (at idle) and 31* mechanical for a total of 47* and it comes in early at 1600. Installing heavier springs will bring the total timing in later, say 3500 rpm but it will still have 47* of total advance.



Ron

[Cooter]

Just as a side note here if you are unsure of trying to weld up the slotts, I have had success using one from an older points distributror. Just look at the "T" bar piece and there should be a number on it like "9" or "10", etc. X by 2 for total. So a "10" would be a total of 20 degrees.

I found Small block "T" bar pieces work as well. A little bit to get 'em apart, but worth it if you are looking to dial it in without tearing your distributor down 50 times. just FYI...

[maxwellwedge]

You said you had 47 degrees with the vacuum line "re-connected". What have you got with the vacuum line disconnected and plugged.....mechanical only?

[HeavyFuel]

Good article in MA this month that talks about this topic.

I too have a MP electronic ignition conversion.  As Rick E at MA points out, the MP distro has design flaws as far as the mech advance is concerned.

My own research, and the fine folks at this site (see: Ron, among others) educated me as to why my car has been running without much power since it's fire up in July.   (not enough initial advance)

After a frustrating summer of driving, the article is a validation of sorts......to have E-booger confirm what's been discussed in this thread:  a certain generation of MP conversion distros should be trashed!

As a last gasp effort to sooth my nerves before putting the car away this fall, I "JB Welded the distro weight slots to reduce the possible total advance.  

Bumped the intial to around 16*, fired her up, checked the total.   It stopped advancing at around 3K, with a total around 35*, give or take.  The idle is alot smoother now, but before I could take it out for a proper test drive, my steering gear/pump shit the bed.

On a promising note, when driving the front of the car onto a pair of those portable ramps that lift the car up about 10", I goosed it a little too much and the back tires broke traction.  That wasn't happening before....the engine would bog first.

(I won't be keeping the JB Weld arrangement.....that's just a little too 'iffy' for me.)  

[BSB67]

slot lengths

[garner7555]

Glad to see this post!  I have the same MP cam and will be dealing with my timing this winter or spring.  Thanks for replies and thanks OP.

[Nickrc3]

Ron,
       I'm interested in purchasing a new Firecore distributor. Please check PM.

Thanks

[GPULLER]

Good choice!
http://www.dodgecharger.com/forum/index.php/topic,102245.msg1212544.html#msg1212544

[warpspeed]

I welded up my advance plate on my 440 several years ago and it worked like a charm.  It wasn't a big issue once I figured out to take the distributor apart.  Has been working flawlessly.  Didn't have the firecore option back then.  Now, I believe I have to do it to my modified 318 engine upgrade on my 85 Diplomat too.

[Nickrc3]

Update:
             Still having woe's with the constant bog or hesitation upon quick acceleration. Ordered a new FireCore distributor and coil from Ron (great service, product, price and delivery time). Received and installed, however, still experiencing the same issues-actually worse. She's now stalling in Drive, as soon as the pedal is depressed. The idle does appear to fallen below 650 RPM's. Unfortunately, it became dark and I needed to return the car back to its sleeping storage stall.

Conditions are as follows: new distributor did affect overall total timing. With the vacuum advance canister disconnected and vacuum source port plugged, the initial timing is set to 15* BTC  - total timing kicks-in @ 2600-3000 RPM's, and now at 33* BTC.





Readjusted idle-mixture screws for maximum vacuum and RPM readings. Their approximately 2.25-2.5 turns out. An interesting observation is the range of adjustment is 1.5-2 full turns from this base, having little or no effect to RPM/vacuum levels.



Still receiving the 'cough' upon manually accelerating the carb linkage in Park.

My last change for the afternoon was to relocate the pump actuator linkage into the center hole within the arm. Doesn't this geometry change result in a quicker shot, but less volume of fuel (less travel on pump rod)?



Additional questions if I may: Do I need the vacuum advance canister to be functional? Installing it would raise the total timing beyond my 33*? Other than detonation, increased engine operating temperatures and possibly poor gas economy, why is a higher total advance not desirable?
                                           If I need to raise the total timing from the mechanical settings of 33*, how is this adjusted within the FireCore unit? Springs were included, but those only affect the rate of advancement, correct?
                                           My initial timing - should I increase to say 18-20*, just as long as detonation is not a problem?
                                           I haven't checked the spark plugs, therefore, have no idea whether those idle-mixtures screws are set too lean or rich. No visual smoke from tailpipes. I'm using those NGK's which have no external electrode. Is there a better perfomance plug for my engine?
                                           I have information on the Carter AVS carb, however, nothing is mentioned on increasing the pump shot volume. Are their different rods available to perform this, as I still feel this may eliminate the 'bog'.

As always, everyone's input is greatly appreciated.
                                           

[b5blue]

Summit sells an adjustment kit, it has red plastic gauges to set total advance. It's 35.00 plus shipping so about 45.00 unless you order more crap to get to 100.00 then shipping is free. Read the info package in your dizzy box for part #.
Download the PDF for Mopar dizzy's as the same will apply. 
 

[Cooter]

Still running that .484/284 241@.050 cam???
If so, it will continuosly bog as Ron mentioned, you have a 'race' type cam in a stock motor.

[Nickrc3]

Still running that .484/284 241@.050 cam???
If so, it will continuosly bog as Ron mentioned, you have a 'race' type cam in a stock motor.

Thanks Cooter - yes, still using that cam.

[firefighter3931]

Nick,

Try bumping the initial timing up to 17-18* at idle. This should give you 35-36* total timing which is still safe with pump premium fuel. It's possible the engine combo is going to want more than 18* at idle and you can check that by advancing the distributor until the vacuum guage stops increasing. GPuller (Reed) has that same cam and his liked 25* of initial timing. Once you determine the ideal base timing then it's time to limit the mechanical advance which is easily done with the Firecore distributor. 

First thing i'd do is to get the vac guage on it and advance the timing for a max vacuum reading and report back. We'll be able to determine the required mechanical advance based on your findings.   

Once the timing curve is dialed in we can move along to the fuel delivery tweaks. The stock carb might have too conservative of a fuel curve for that cam profile. Maybe you can tweak the jetting to accomodate the increased fuel/air requirements or it may just boil down to a better suited carb for the application.


Ron

[66FBCharger]

Approximately how much does the Firecore dist. setup for a 440 cost?
Is there any way to determine what camshaft is in an engine?

[firefighter3931]

Approximately how much does the Firecore dist. setup for a 440 cost?
Is there any way to determine what camshaft is in an engine?

66FBC,

There are several options with regards to the Firecore Product line :

(1) Firecore Billet Ready to Run distributor with built in Module
(2) Firecore Billet Plug & Play for use with OEM style external module
(3) Firecore Billet Mechanical advance for external box (MSD/Mallory/Crane etc....)

What do you have currently on your car ?



Ron

[66FBCharger]

Approximately how much does the Firecore dist. setup for a 440 cost?
Is there any way to determine what camshaft is in an engine?

66FBC,

There are several options with regards to the Firecore Product line :

(1) Firecore Billet Ready to Run distributor with built in Module
(2) Firecore Billet Plug & Play for use with OEM style external module
(3) Firecore Billet Mechanical advance for external box (MSD/Mallory/Crane etc....)

What do you have currently on your car ?




Ron

Ron,
I have a Mopar Performance dist. with the orange box. The engine is a '69 440. I bought the car with the setup it has. I am not sure about the internals. I have no idea what the cam is. That is why I was wondering if there was anyway that I can ID what the cam is.
The rest of the combo is I have an Edelbrock AFB (which I don't like and am considering getting a Holley this year), and a set of hooker headers . It is a four speed with 3.54 gears.
I would be interested in the setup that has everything internal to the dist. I would prefer to not have to mount a separate control box. I was considering a Pertonix kit but I like the Firecore's ability to easily change the advance.
John

[firefighter3931]

Ron,
I have a Mopar Performance dist. with the orange box. The engine is a '69 440. I bought the car with the setup it has. I am not sure about the internals. I have no idea what the cam is. That is why I was wondering if there was anyway that I can ID what the cam is.
The rest of the combo is I have an Edelbrock AFB (which I don't like and am considering getting a Holley this year), and a set of hooker headers . It is a four speed with 3.54 gears.
I would be interested in the setup that has everything internal to the dist. I would prefer to not have to mount a separate control box. I was considering a Pertonix kit but I like the Firecore's ability to easily change the advance.
John

Hi John,

The Billet ready to run distributor is what you're looking for then....several members are running that distributor with great results. I'll send you a pm with details so we don't HiJack Nick's thread. 


Ron

[Nickrc3]

...O.K., making some progress. I took the day off from work to devote into the tuning of the 440.
First thing this morning I completely disassembled the AVS carburetor in preparation for a rebuild. I was unsure on the condition, so figured a rebuilt wouldn't hurt in my diagnosis.
Initially noticed the float levels were way off:
.
Readjusted to 7/32" level and 23/32" drop. Nothing unusual other than some miscellaneous crud. The one thing that kept me confused was why the accelerator pump doesn't squirt throughout the mechanical range of motion with the primary throttle plates. The plunger movement is 7/16" w/ throttle plates about a 1/4 open. I didn't fret, as I understand the accelerator pump circuit is likely for initial throttle response. I reassembled as it was taken apart, and everything appeared fine.
Completed carburetor was installed onto stock intake manifold.

After some squeeze-bottle priming, she started and idled nicely, however, still had the 'bog' upon hard throttle application.

Taking Ron's advice, I moved the timing north while observing the vacuum gauge for max reading. I twisted the distributor to 24* with no adverse issues, though I now could not lower the RPM's from 1100. The idle screw was backed out, but still the idle wouldn't drop down to 700-800.
I finally decided on 21* w/16" of vacuum. Vacuum advance disconnected and plugged.

Idle-mixture screws tweaked to max vacuum and RPM.
Took the car out and everything appeared fine with 'normal' acceleration. Engine response appeared improved. When I reached my secluded tuning area, I immediately punched it and yes, it did 'bog' and hesitate, then stabilized and off she went. In fact, the vehicle pushed me back into the seat and continued to pull hard through 5500 RPM's, burning tires and swinging sideways through 1 & 2. Once Drive was reached, she straightened out.
A young man was loading a delivery truck and observed this crazy older guy performing these gyrations in this odd car. Upon returning to the scene to view the rubber patches left behind, he commented how angry the engine sounded. I mentioned these burn-out activities are my testosterone release. He chuckled.
Seriously, I think Ron and Cooter hit the nail on the head - the cam is just too much for a relatively stock engine. The tuning is crazy, so I'll probably have to tolerate with the 'bog'.
Maybe I'll get bored and installed the Lunati 'Voodoo' series cam in a few months.

Ron and Cooter - couple questions if I may. At 24* initial, the idle RPM's would not drop below 1000, as the idle speed screw was backed out. Why is this? What would cause a significant drop in RPM's upon shifting out of Park into Drive? A vacuum leak? I've got to maintain a relatively high idle @ 800 RPM's, so upon shifting into Drive, it won't die.
I probably won't reinstall the vacuum advance. If I did,the total advance would shoot up into the 40* range. Would a problem exist if I'm NOT experiencing detonation or increased engine temperatures?
Ron, should I leave the vacuum advance line off and play with the mechanical advance within the FireCore distibutor? She's coming in around 2500 RPM's.

Thanks Guys!

[firefighter3931]

In fact, the vehicle pushed me back into the seat and continued to pull hard through 5500 RPM's, burning tires and swinging sideways through 1 & 2. Once Drive was reached, she straightened out.

Nice work Nick 

A young man was loading a delivery truck and observed this crazy older guy performing these gyrations in this odd car. Upon returning to the scene to view the rubber patches left behind, he commented how angry the engine sounded. I mentioned these burn-out activities are my testosterone release. He chuckled.

Crazy old guy huh....that made me    Sounds like you woke the beast up ! 

Ron and Cooter - couple questions if I may. At 24* initial, the idle RPM's would not drop below 1000, as the idle speed screw was backed out. Why is this? What would cause a significant drop in RPM's upon shifting out of Park into Drive? A vacuum leak? I've got to maintain a relatively high idle @ 800 RPM's, so upon shifting into Drive, it won't die.
I probably won't reinstall the vacuum advance. If I did,the total advance would shoot up into the 40* range. Would a problem exist if I'm NOT experiencing detonation or increased engine temperatures?
Ron, should I leave the vacuum advance line off and play with the mechanical advance within the FireCore distibutor? She's coming in around 2500 RPM's.

Thanks Guys!

You don't have a vacuum leak but the cam needs/wants lots of base timing so the idle speed will be higher. To lower the idle speed would require retarding the initial timing and that just kills "off idle" power and throttle response. It's a catch 22.....you can't have both at the same time with the current setup. 

The problem is ; cam is too big for the current torque converter. When you drop it into gear the engine is fighting the "too tight" torque converter. This often happens when cam swaps are done and the stock torque converter is still in place. If you have the right converter for the application the rpm's should only drop 200-300 when you put it in gear. 

So, you have three options ;

(1) live with it
(2) install new cam
(3) install new tq converter

Quick explanation ; The stock converter is rated at 1500-1800 stall speed. Your cam doesn't hit the sweet spot until 2500 so the engine is lugging briefly until that sweet spot is reached when you mash the pedal. This is what is creating the hesitation. Sometimes you can cover it by increasing the pump shot but it will never be optimal. 

If it's running good i'd leave it alone and not bother with the vac advance. I never use it and it can cause surging issues at cruise speed on the hwy under constant load. Especially true with a lumpy aftermarket cam.

The 268* Lunati cam would be a good choice for this combination. 



Ron

[Nickrc3]

Ron, thanks so much for all your time in identifying my engine issues and providing a thorough explanation on resolving them.
Swapping out the torque converter is an intriguing thought. Can you further explain converter stall speeds and how they affect a street-driven vehicle? Will transmission shift patterns be altered? Basic driveability be adversely effected, including MPG?

As you mentioned, I may just live well-enough alone, as I'm spending more time and effort into my 68', which is an original big-block, 4-speed vehicle. It certainly needs it!


Lastly, other than the FireCore folks, do you provide distribution services w/ pricing for other manufacturer's?
PM me on details if you wish.
Thanks again.

[firefighter3931]

Hi Nick, you're more than welcome....allways glad to help those who are willing to learn. 

The Tq converter is a key player in the overall success & drivability of any car. As you've seen with your own car....a mismatched component will affect drivability. In your case a high quality tq converter that flashes up higher would only enhance your driving experience. When the converter works right it behaves just like a stocker under normal driving conditions but when you drop the hammer it flashes up to the rated stall speed and then all hell breaks loose....lotsa fun ! 

This is one area where it pays to spend the extra $$ because you definately get what you pay for when it comes to aftermarket Tq converters  If you're haappy with the street manners of the engine combination other than the soft launch then a better converter is certainly a good way to go. If you'd like to tame the engine down a bit then a cam swap that is compatible with the current converter will also work. 

With a quality converter there should be very little drop off in fuel economy if at all. Converters are now built with efficiency in mind and most quality street converters have very little slip. Most are as good or better than the factory converter. I ran a 4400 stall Dynamic with my old 446 combo and it was a really nice converter....felt like a stocker pulling away from the light at low to moderate engine speeds....yet flashed up perfectly when full throttle was applied. My current build is a 572 stroker making 720hp/725tq and i have a custom built 5000 stall unit and it drives just like a stocker. You wouldn't even know it's in there until the pedal hits the metal....then it's tire frying time. 

Hope this helps explain the converter concept and how important it is in the overall success of the car's performance. 

As for Firecore ; i really like the products and the build quality is top shelf. Excellent value for the dollar and great people to work for. Rick is a Mopar guy through and through and has spent a lot of time designing this product line and incorporating the superior features that make the product so user friendly. I was asked to become a representative and am certainly proud to be part of the FireCore team. This is the only product line that i'm directly involved with.


Ron

[Nickrc3]

This is one area where it pays to spend the extra $$ because you definately get what you pay for when it comes to aftermarket Tq converters  yesnod If you're happy with the street manners of the engine combination other than the soft launch then a better converter is certainly a good way to go

Ron, any particular brand/type you recommend, like the PTC 11" street hemi or T/A unit with a stall speed @ 2500? Again, an update to the converter will not affect my highway cruising speed?

[GPULLER]

Like Ron said, I'm running the same cam and my combo liked 25 deg initial.  I didn't have a vac gauge when I set the timing, just advanced until I got the highest idle and engine would still start without kicking back. Also I run a Holley carb, so can't help you with adjusting your Carter.  I have drilled small holes in the throttle plates and adjusted up the secondarys a little to get idle quality.  All those adjustments where done before the Firecore dist, and it was all a band-aid.  Getting the timing right was the biggest improvement, it all starts there.
I've never got idle down below 1000 RPM, likes about 1100.  I'm running a slightly looser converter.  I don't have any hesitation or bog.  I think you might want to try bumping up the initial timing and see what happens.  I locked the total timing at 35 deg, and do not run the vac advance.

Reed

[firefighter3931]

Either the PTC 11in or T/A street hemi converter would be a good choice. 


Ron

[Dino]

I run that same old purple shaft in a similar block with a thermoquad and 2.96 gears.  Yep the cam is all wrong and it'll be the reason why some day this engine will get pulled.  Still I got mine to run without any bog and it's a solid cruiser but it so desperately wants that new cam.  I'll miss the lumpy idle though...

[b5blue]

My engine had an old drag race vintage build with the Mopar 509 cam and closed chamber heads when I bought it. Now with 346 heads and a Resto Roadrunner cam it drives really nice. 

[Nickrc3]

...current update - my decision to either replace the camshaft to a modern grind or replace the torque converter?
I chose the converter change for the reason to retain the RPM powerband designed for the PurpleShaft's camshaft. In addition, I really didn't want to break down the engine (again) and go through the labors of cam degreeing, break-in, possible leaks, etc.

A few weeks back, I contacted Kenny @ Performance Torque Converters (PTC). As recommended by FireFighter (Ron) and others, Kenny suggested the 11" street hemi converter. Four days later, it was delivered to my doorstep.



Careully installing the PTC unit into the transmission (after replacing the seal) and observing she's fully engaged.


So now I'm all excited, raising the transmission up into position via a motorcycle jack. A slight shove forward and she's resting on the engine dowel pins.
All five bellhousing bolts get hand started and tightened. I then look directly up into the flex plate/converter cavity and notice the flex plate does not match the convertor bolt pads  Oh S%#t! Did I feel like a complete buffoon, never bothering to confirm the bolt centering of the new converter to the existing flex plate. This screw-up ended any motivation to continue wrenching that day!
The following day I did contact PTC and they had the correct Mopar flex plate in-stock (bolt configuration of 10" OC). Again, it was delivered within three days.

So, this President's Day weekend I finally removed the transmission, replaced the flex plate and reinstalled. Oh, don't forget the starter shield!


An unrelated issue that continually annoyed me was this constant exhaust manifold leak (ticking). I observed paint discoloration of the side of the engine block adjacent to the heat riser. Apparently, exhaust was leaking from the extended shaft on the heat riser. Since the riser was already  hard-wired open, I chose to weld a bead around the area to permanently seal. Also note the purchase of Percy's aluminum gaskets.


With everything together now, I start the engine and immediately hear this nasty clanking sound from the transmission/converter area. Oh no, here we go again!
Turns out the new converter bolts (on 10" diameter) ride outside the shallowed area of the original dust shield.

-note scrape off-center, upper right.
My attempt to extend the shallowed area with a block of wood and some sharp hammer blows was unsuccessful - it still produces noise.
Anyone have an aftermarket source for these modified dust shields?

With dust shield removed and all fluid levels triple-checked, the engine is restarted.  Immediately I sense a smoother Park-to-Drive transistion -  no more violent motion. Also, I can now obtain a manageable RPM setting of 830. As Ron indicated in his earlier response, the higher stall speed solved this issue.
Timing was bumped to 24* initial, 38* total @ 3000 RPM's. Vacuum reading peaked @ 15". No detonation, no starter bump-back - everything's good.
The test drive went very well. Drove immediately to my secluded area designated for burn-outs, and dropped the hammer.  Wow - the engine immediately roared to life and quickly rev'ed to 5800 RPM's before shifting into 2nd gear! Of course, both rear tires were smoking with the rear swinging in the torque direction.
She continued winding upon the final shift of Drive, which was followed by a nice, distinctive chirp. MPH's were now getting a bit high for my comfort level - time to back-off.
That engine roar, the 'thrown back into the seat' feeling of brute torque, smell and sight of burning rubber, and my ability to countersteer the goobs of torque,  instantly transports me back to 1976 with exiting my High School parking lot each afternoon. I sure hope I never tire of this performance sensation! 
I am very satisfied with this modification. I did notice more acceleration is now required from a stop to propel the vehicle (from 0-30 MPH), and the RPM level has increased within highway cruising speeds. Obviously mileage will be affected, but this isn't my concern. The car gets driven, maybe, 25 miles a month. 
I wish to thank everyone, especially our Moderator, 'FireFighter 3931' for all responses and accurate assessments to the issues faced. You Guy's are great!
Maybe soon, I can learn how to post a You-Tube video of the performance. 

[Dino]

I will send you a plane ticket and money for the parts, come do this to my car!  You got me all excited now!   

Thanks for the write up, I do believe a video is in order.   

Wise decision on the Percy's.   

[firefighter3931]

Hey Nick....sounds like we're starting to have some fun ! 

Glad the tweaks are working in your favor. I had a feeling you'd be happy once it was all dialed in 

As for the dust shield ; you can trim a bit off the top tabs that normally tuck inside the bell housing and use a few washers to space the shield back a bit. If you can find a dust shield for a 383 it should have the scallops located in the right spot for the PTC converter. All 383's came with an 11in converter using the 10in bolt spacing that is on your new PTC Tq Converter.   

Good call on the Percy's exhaust gaskets. 


Ron

[GPULLER]

Good to hear it's coming around!