'72 413 Distributor Tuning

[BigAlsVehicleEmporium]

Hi,

I went to put a Pertronix Ignitor III electronic ignition module (p/n: 71381A) in my distributor today and found a couple of surprises. It looks like someone changed one of the distributor advance springs at some point, as I've never seen one like this. Is the red spring in the upper right stock?



I'd like to replace these springs as they're not giving enough advance per the Dodge spec. The Dodge Motorhome parts book doesn't list numbers for the advance springs, that I could find. What part number/combo springs do people recommend? Is it Mr. Gasket 925B?

More details for those interested:

1972 Dodge 413 V8 with 3656365 points distributor.

Before tearing into anything, I wanted to see how it was set up. I verified the TDC timing marks on the damper & timing cover were correct by pulling the #1 spark plug and verifying TDC. Then I disconnected the vacuum advance hose and lowered the idle to 500 rpm to try to take the mechanical advance out of the equation. I nearly gave myself a haircut trying to see the timing marks with the engine running, so I used a boroscope camera instead. I have a digital timing light that allows me to dial in advance in degrees and read straight off of the TDC marks. It also gives rpm & dwell readings.


At 500 rpm, advance was 2 degrees After TDC. It should be 5 degrees BTDC +/- 2.5 degrees. Raising RPM to 550 and then 900 brought no additional advance. Per specs, 550 rpm should have an advance of 1 - 8 crankshaft degrees. 900 rpm should have an advance of 16 - 20 crankshaft degrees. At 2k rpm, the total advance was 19 crankshaft degrees, which means that the mechanical advance was adding 21 crankshaft degrees. Per spec, this should be 24 - 28 crankshaft degrees.

The vacuum advance fell within spec, 7 degrees at 7" and 20 degrees at 12".

I pulled the distributor and disassembled it. Shaft side play was 0.005" at 5 lbs of pull, so barely within spec and end play was 0.013, within spec as well.

Factory Specs:

[RockwoodMike]

It is that other spring that is holding back your advance..That red spring has a slotted configuration to allow advance at off idle speed (900 rpm)..the other one does not. It is holding back till you hit the higher rpms.

Places like Jegs and Summit should be stocked with dist. springs for Mopar..full kit of matched springs so that you can get the factory specs back.

That 2 degrees ATDC needs to be changed. Maybe 7 BTDC at idle would give you a performance boost.

[Eyez Open]

Lots of information there, somebody curved the distributor to there liking. Based off what I think I've read they the springs are to light for your intentions, staying to factory spec that is. If you set your static advance at 4* there should be no advance taking place until 800/1000 rpm.

Since your detailed enough to check your harmonic balancer has not slipped I might suggest a timing tape. The good news would be your carb is definitely on the idle circut...lol I think. Is it a thermquad? If so can you close down the idle screws and starve the engine? There is a reason for that question.

[RockwoodMike]

https://www.summitracing.com/parts/sum-850121/make/chrysler

Here is something from Summit. Notice that the springs ends are slotted..that is the problem with the second (left) spring..

[Eyez Open]

https://www.summitracing.com/parts/sum-850121/make/chrysler

Here is something from Summit. Notice that the springs ends are slotted..that is the problem with the second (left) spring..

You will not see me do this to much on this board. Do not buy those springs stick with moroso. They are far to light. Now I said onto one of the best mopar tuners/builders in the business. Beyond the show he puts on note one thing, when he know the engine is stable he times it twice and done. 36 total meaning 16 initial and 20 mechanical advance...no vacuum allowed  I placed this video here as a informational piece only and for entertainment.

Actually let me amend that to calling Petronix customer support. They have dedicated support for such matters. It is there business springs and weights are one calibrated system, mix matching can be harmful.

https://youtu.be/ehcNnf_BLHQ

[RockwoodMike]

yea, I never was very impressed with him..Watched the whole video and what I saw was he was just guessing on what to do next. He retarded the timing and wondered why he lost performance..Never even used a timing light..And after all said and done, he barely got it to factory specs..

https://www.youtube.com/watch?v=EWihFRxLrzY
Here is a man that at least uses a timing light and got it way over factory specs..From down under!!

As for those springs, how do you know what the specs are saying they are too light??

What Big Al said was he wasn't getting enough advance..In other words he need to lighten the springs..

This kit that I linked give you several springs to test..Put a set in and see..go to a different set if the first doesn't work..

There is nothing wrong with those springs I linked.

Maybe you could create a link for Moroso springs..At Summit, I search Moroso dist spring kit Mopar..Nothing ..

[BigAlsVehicleEmporium]

RockwoodMike,

Thanks for the spring recommendation! I've got to get the distributor back in for a trip on Friday, so I'll see what I can get quickly!

And agreed, an extra 9 degrees of static timing is bound to give me a boost in power and economy. 7 BTDC is the number I was thinking too.

[BigAlsVehicleEmporium]

Eyez Open,

Thanks! My carb is an Edelbrock 1405 that I added the electric choke kit to, to make it a 1406. I cleaned the carb out when I got the rig and it looked great inside. I can't believe how well this engine will run down to 500 and even 450 rpm.

I haven't tried closing the idle screws. I haven't tuned the carburetor beyond it's base idle specs because I knew the timing wasn't right and there's no point in tuning a carb until everything else is dialed in. Once I get the ignition system back together I'll try killing it with the idle screws to make sure that other parts aren't leaking fuel.

[BigAlsVehicleEmporium]

Thinking on it overnight, I might just leave the springs that are in it. This motor home sees 97% of its running time at 55-65 mph. That'll be around 2,800 rpm, give or take. I don't really care about perfecting the advance curve at lower speeds, I just want to make sure I'm all in at cruising speed so I'm getting as much power and, more importantly, economy out of this V8 that I can. My mileage has averaged 6.5 mpg and I want to hit 8 mpg before my trip from Atlanta to Seattle in September. I think I'll put it all back together with the Pertronix and make sure the advance comes in fully by 2,500 rpm or so. If not, then I'll dive into swapping springs.

Dave has a great article on here about tuning distributors. Following that advice, I want to limit my total advance under real conditions to 50 degrees or so. I'll start with 7 degrees static and then see what "all in" gives me on the vacuum advance can and the mechanical advance. Hoping for something like 26 degrees mechanical and 20 degrees vacuum. With this motor, it doesn't seem like the "all in" case for mechanical and vacuum advance can overlap (I'm not going to get 18" vacuum at 2,500 rpm I don't think) so I'm not too worried if the maximum advance technically possible is a few degrees above 50.

Here's a link to Dave's article. It was posted back in 2010. Dave, I'm always interested to hear from your experience so if you've got the last section on setting up new curves rattling around, ready to post, I'd love to read it!
https://www.classicwinnebagos.com/forum/index.php?topic=4215.msg12458#msg12458

[Eyez Open]

S.O.B. Mr. Chieftain appears to be David Ray..also known as the Igntion Man.LMAO it's is quite odd to see such a well written and factually correct article on a vintage RV site..then again perhaps not...Classic Winnebago has been extremely helpful to me in my own restoration.

You cannot go wrong following that article, it was very well written from a layman's point of view. I would get in touch with Petronix about the springs,it's just a phone call after all. I say only because those springs are a unknown quantity, they might very well be far to light causing issues at higher rpm..weights go way to far. And yes Petronix does make springs, below is a link. Have fun it can be eye opening, recently I rebuilt my carb the initial fuel mixture was a tad lean causing a lean backfire pop thru the carb. Now I can tell you that was really quite startling..having a detonation going off in the cab. Checking for fringed hair is not a good thought.

https://pertronixbrands.com/products/pertronix-d700700-advance-spring-kit-flame-thrower-billet-distributor?variant=42604227526827&utm_source=google&utm_medium=cpc&adpos=&scid=scplpshopify_US_4572370337828_42604227526827&sc_intid=shopify_US_4572370337828_42604227526827&gad=1&gclid=Cj0KCQjwzdOlBhCNARIsAPMwjbxbkmNKqIxLuKXX4S58fRHzTW96uTmZIFcpyr0uEUFwageKe7GR8hMaAhenEALw_wcB

Ok lol after following David Ray for a while and watching his reactions towards some product lines..man he can be terse at times. If you don't know what your doing just ask!

The guy is absolutely priceless, old school tough love..perhaps the world would be in a much better place if there was more of that.

[DaveVA78Chieftain]

Not sure who David Ray is but I am David Bailey.

My intent of the article was simply to explain the mystery of tuning related to stock ignition and carburation not from a racing perspective but from an RV street performance perspective.  Because the internet has changed so much since 2010 I need to update several of the links.  Some no longer exist (people pass away and the info is lost) however I captured many articles and have them on my hard drive.  Photobucket, which was once free, is now a pay site, so I have to rehost the photos.  I am 71 so no spring chicken.  I will rehost the pics to my website which should stay up as long as I am still living.
  Sadly, I no longer have my 78 Chieftain so I no longer have a platform to tinker with. I did install a MSD 6A system in it but never really got to play around with it much so the additional stuff I wanted to experiment with never got done.

[Eyez Open]

David Ray was on the design team for GMs ignition division, I believe he actually developed HEI. He has been on the net for a very long time, a bit crass but he is aged along and tolerates little misinformation when he gets involved in a thread,not the guy to debate approach or ignition theory unless your of equal intelligence and experience.

Your article almost emulates his thought processes, including the billet distributor opinion..almost striking. I grew up in a service garage in the 60s/70s, spent countless hours working on working on engines,tuneups were the bread&butter,screw ups were not tolerated. Rays knowledge explain why things work the way they do, as your article does also. Personally I only know what to do,and not to do..you guys explain why things work the the way they do. It's been 40 yrs since I've done this type of work, it's very nostalgic to me, I really wish I could have a brief time with my father..lol hey dad check this out. It would be a fascinating conversation..especially efi.

Well done Dave, that article was very well done. Definitely sticky material...but that's a opinion only.

[DaveVA78Chieftain]

It was born of frustration in trying to learn this stuff.  What many do not grasp is the same principles that apply to old school setups like these also apply to the computerized systems.  They just monitor a lot more things now days to better control the A/F mixture/spark timing. Rather than manual adjustments your now changing computerized data.

[RockwoodMike]

What many do not grasp is the same principles that apply to old school setups like these also apply to the computerized systems.

I am working on a 94 Ford E350 van with the 460. It has the OBD 1 EEC IV computer. There is a thing called a SPOUT connector that you unplug when setting the timing..You set it at 10 BTDC..Then you are done. Put the SPOUT(Spark Output) back in and the computer will take it from there..There is no weights or vacuum advance..

Computer will advance or retard timing to it's liking..And that is 30 year old technology!!

[BigAlsVehicleEmporium]

Dave, in addition to all the great info in that article, the bold reminder that the service manual gives specs in distributor degrees rather than crankshaft degrees saved me a lot of headache. I was trying to figure out why I was getting about twice the advance that I should when that note in your article had me go back and take a closer look at the specs!

Did you replace the 78 Chieftain with a different RV or free up a bunch of space, time, and money instead?

[DaveVA78Chieftain]

It's getting harder and harder for my wife to get around now (power scooter) so it's not something easily done anymore so no RV.  Been thinking about a popup camper for going to NASCAR races (by myself) though.

Been looking through files I used to develop a lot of this info and found my excel charts for making power curves of this stuff.  Makes it easier to visually see what your doing and the effects of changes made.  While I originally used Excel (advantage of work environment) to develop all this I now use LibreOffice (freeware) which basically does everything the high cost MS Office does.