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