Talk:Hot rodding the HEI distributor

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==Possible copyright/ownership conflict==
 
This appears to have been copy-pasted from here: http://67-72chevytrucks.com/vboard/showthread.php?t=88002 . Not sure if it's the original author that did the copy-pasting, in which case it would be OK. --[[User:Jon|Jon]] 15:57, 1 March 2007 (PST)
 
:I added credit for the thread where the article was taken.--[[User:Cobalt327|Cobalt327]] 07:54, 19 June 2012 (MDT)
 
  
==Photos for possible use==
 
 
[[File:HEI CAP- ELECTRODE- INSULATOR- COIL DIAGRAM.jpg|200px]]
 
[[File:HEI MAGNETIC PICK UP COIL V6 EVEN FIRE.jpg|200px]]
 
[[File:HEI COIL DATA RATIO WINDS ETC.jpg|500px]]
 
[[File:DIST THRUST BEARING-SPACER 003.jpg|200px]]
 
[[File:ROTOR where weights hit2.jpg|200px]]
 
[[File:HEIadvlimitlock2.jpg|500px]]
 
[[File:Hei mechanical ADVANCEslots and pins 0011.jpg|200px]]
 
 
==Opinion on [http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor#What_vacuum_source_should_I_use-_manifold_or_ported.3F Cliff Ruggles' vacuum advance advice]==
 
Note: Cliff is missing the essential point here. This is not about what some engine "likes" or not but pure simple science. The whole idea with adding vacuum advance is to compensate for the fact that the thinner idle/cruise-mixture are burning slower, meaning it will need an earlier spark or more timing-advance to burn properly. A properly set full manifold vacuum will also prevent detonation since it goes off as soon as the engine starts working/loosing vacuum.--[[193.71.29.173|193.71.29.173]] 05:52, July 1, 2012‎
 
 
:You need to realize that at idle the engine is running off of the idle circuit. If the idle circuit is correctly calibrated, there is no need for extra advance unless the can timing is causing a lean condition at idle speed. The added advance from the vacuum advance using manifold vacuum can help when a larger cam is used that has less idle vacuum.
 
 
:Under cruise conditions it makes absolutely '''NO difference''' what the vacuum source is for the vacuum advance.--[[User:Cobalt327|Cobalt327]] 18:49, 1 July 2012 (MDT)
 
 
==Revision details==
 
On 06-24-13, anonymous user 72.205.31.197 removed a section "advertising" MSD. Original revision was on January 22, 2009 at 12:50, by anonymous user 68.35.121.35. This can be verified by checking the page history.--[[User:Cobalt327|Cobalt327]] 18:58, 24 June 2013 (MDT)
 
 
==Info to research/verify for possible integration into article==
 
Vac adv article rocky rotella: http://www.highperformancepontiac.com/tech/vacuum_advance_tech/viewall.html
 
 
MAJOR HEI THREAD:  http://www.chevelles.com/forums/showthread.php?t=327577
 
Advance chart originally from: http://forums.performanceyears.com/forums/showthread.php?p=3638443#post3638443
 
 
 
What type of pins are on the dist you're working on?? Big pin with integral flange, chevy type big pin without integral flange, small pin??? I will assume you are working with a Pontiac HEI which has big pins with the integral flange.
 
 
The 41 weights are the powdered metal type and thats not real great but it's not bad either. The thing with them is they have a triangulated boss on them which means they were originally off a chevy dist. Late chevy shafts have dispensed with the nylon pads under the weights in lieu of a raised stamping exactly the same height as the triangulated boss on the weights. Can use them on big pin dists but first you will need to grind down the boss and not all the way away because the Pontiac dist has the lil flange on the pin that the chevy didn't have. Sneak up on it .
 
 
Regular solid steel weights are my preference and all of the factory ones from GM were heat treated. Without getting into all the different possibilities they had for them , I'll let you tell me what you got to pick from and we can cut to the chase quickly.
 
 
Center cams were all the same as far as having no wierd needs for what they would or would not fit. There are many that are better than the 375 in my opinion, but again what have ya got???
 
 
My opinion is the 375 and 41's suck, unless thats all you got, then my opinion is still the same...Junk, compared to other choices. But still very workable.
 
 
Nothing really special about em at all and really I don't like the low hump in the middle of them, but someone apparently does for some reason... care to share why???
 
 
Numbers on weights and cams are identifier numbers for factory use, have to be there or you'd never be able to decipher, without much work, what is what without a id number to tag it with.
 
END
 
 
60 seem to be shaped identically to the stamped 139. The cast 41 and stamped 106 are shaped identically, and look like the would give a little less total advance (the leg that follows the center is in just a touch tighter than on a 139 or 60).
 
END
 
FWIW, this post you made back in 2003 is one of the things that has me trying to figure out what a "good" curve really is:
 
 
Not only does the center cam control the amount of total centrifugal advance capable. It also controls the rate of the advance(speed) along with the springs. The springs will control the actual speed of the advance, but the cam controls both the total amount AND the specific rate in conjunction with the speed the springs allow. Much more critically than the point dist did. If you look at different cams you'll see that some have a smooth slow ramp, some have a smooth beginning ramp and a quick ending ramp, some have a fast opening ramp and slow down towards the end, and on and on. Swapping these things around will allow one to tailor a curve more suitable for a particular combo than another. Sometimes it will and can cause more problems than before too.... These HEI cams are about as critical tolerance wise as the regular camshaft in the block is.
 
 
The 375 cam will allow excessive override. i believe more than 13 dist degrees. That means it will reach a peak limit where you think it will be done advancing and then boom, extra timing on top of the 13, how much??? depends on how tight you keep winding it till it scatters parts violently or till you hit the end of the slots in the top plate (unlikely but possible) or whichever comes first there. I garbage can the 375 weights for this reason.
 
 
22 crank degrees can be achieved rather easily...
 
Take your 053 weights and go find a 406,364,or a 370 cam and have at it.
 
 
Big pin 106's or small nylon bushed pin 106's???? Same as the 139's.
 
 
the Rocky Rotella chart.. "w/centerplate numbers up" ..... using #139 weights.
 
 
Centerplate# ========== Weight# ===== Crankshaft Degrees*
 
...#346================139==============24*=====
 
...#349================139==============20*=====
 
...#361================139==============24*=====
 
...#363================139==============15*=====
 
...#364================139==============18*=====
 
...#365================139==============06*=====
 
...#368================139==============20*=====
 
...#369================139==============22*=====
 
...#370================139==============25*=====
 
...#375================139==============26*=====
 
...#383================105==============24*=====
 
...#389================139==============21*=====
 
...#393================139==============07*=====
 
...#398================139==============24*=====
 
...#399================139==============25*=====
 
...#400================139==============14*=====
 
...#401================139==============24*=====
 
...#402================139==============26*=====
 
...#404================139==============16*=====
 
...#406================139==============21*=====
 
...#416================139==============24*=====
 
...#417================139==============24*=====
 
...#422================139==============20*=====
 
...#432================139==============24*=====
 
...#438================139==============18*=====
 
...#444================139==============21*=====
 
...#445================139==============19*=====
 
...#446================139==============17*=====
 
...#449================139==============24*=====
 
...#451================139==============20*=====
 
...#452================139==============24*=====
 
...#459================139==============25*=====
 
...#462================139==============19*=====
 
...#467================139==============24*=====
 
...#469================139==============21*=====
 
...#470================139==============24*=====
 
...#481================139==============14*=====
 
...#482================139==============24*=====
 
...#483================139==============24*=====
 
...#485================139==============25*=====
 
...#486================139==============22*=====
 
...#508================139==============24*=====
 
http://forums.performanceyears.com/f...43#post3638443 post #32
 
 
Originally Posted by Sun Tuned
 
I figure now would be a good time to give a little back to a hobby that has given so very much enjoyment to me over the years. Some of you will have seen this elsewhere on the web; so to speak,so be patient, there are probably some here that have not. At the risk of offending those who would wish this to be kept shhhhhh, you may want to leave now so as not to be mad again.
 
I say again, because this is not the first time I have performed this trick for an audience.
 
It was FREE the first time so I figure why change up the deal now.
 
 
Centerplate#===========Weights#=====Distributor Degrees*
 
...368=================139=============10======
 
...406=================139=============12======
 
...349=================139=============15+=====
 
...371=================139=============09======
 
...489=================139=============14======
 
...375=================139=============13+=====
 
...364=================139=============12======
 
...397=================139=============12======
 
...370=================139=============12======
 
...346=================139=============11======
 
...396=================139=============11.5=====
 
...398=================139=============10.25====
 
...383=================139=============12======
 
 
That should be enough to get you started. The springs I'll let everybody figure out on their own. These are probably the most common ones, but that will give everyone a basis with which to get started anyway. Anyone need any help, you now know where to find me.
 
 
The 48 weights are a powdered metal version of like a 139 set. G.M. cost cutting idea.
 
They should also have a triangulated raised boss on both sides at the weight pin hole area.
 
Work fine for street although not my first choice but they are o.k..
 
 
Circle trackin it with em ..... they suck. They will fracture and blow in pieces like a hand grenade, taking parts of the dist at times with them as we have found out.
 
Then again they weren't designed to operate a 7500 rpm either.
 
 
The 398 centerplates are difficult to find in the junkyards.
 
I'd suggest contacting Sun Tuned at tn47@aol.com --- phone number to 901-412-4414 ...
 
He offers top-quality recurve kits that contain a laser cut centerplate resembling the original GM units. He'll set you up right.
 
 
But whatever you do, stay away from the generic, off-the-shelf curve kits. They're horrible!
 
Quote:
 
Originally Posted by Rocky Rotella
 
I think the "10, 11, and 12" Sun Tuned refers to is in distributor degrees.
 
That'd be 20, 22, and 24 crankshaft degrees, respectively.
 
10 initial with 20 centrifugal should be no problem with the KRE heads. If the engine likes more advance at idle, add about 10 degrees of manifold vacuum advance.
 
 
#053 weights typically reduce the amount of mechanical advance by about 1 degree when compared to 139 weights.
 
 
 
Another option is to rebuild your existing shaft. As long as the shaft itself isn't too scored where it rides on the bushings, you could go to NAPA or any other "real" parts store and get new pins and bushings for the weights.
 
 
Useful (NAPA) part numbers for HEIs:
 
 
DP109 HEI weight pins
 
DP112 HEI weight plastic bushings
 
DP114 HEI distributor weight "stamped 106"
 
DP115 HEI dizzy weight "stamped 139"
 
DP126 HEI dizzy weight "stamped 105"
 
 
MP100 (GP Sorensen EL315) HEI yellow color code V-8 pickup coil
 
(Chevy, Caddy except Seville, Olds Toronado)
 
 
MP101 (GP Sorensen EL310) HEI Blue (or black) color code V-8 pickup coil
 
(Olds except Toronado, Buick, Caddy Seville)
 
 
MP102 (GP Sorensen EL359) HEI clear color code (Pontiac) V-8 pickup coil
 
 
(The GP Sorensen pickup coils are about $16 instead of NAPA's $40.
 
The GP-S ones I bought are even made in the USA!)
 
 
Distributor shaft washers (pack of five) GM #1837617
 
 
If you use an in-cap coil, (1) be sure to follow color code guidelines: Yellow pickup coil goes with ignition coil having red and yellow wires. Blue (or black) and clear color code pickup coils go with the ignition coil that has red and white wires; and (2) use a low-resistance carbon button to transfer the spark to the rotor. MSD, Crane, and others sell them. Crane's costs less than the MSD unit.
 
 
 
Originally Posted by Schurkey View Post
 
I spent 15 years looking for the information in the link I posted earlier. In my case, it was to prove that coil-in-cap igniton coils and HEI pickup coils are designed as a matched set --
 
 
Chevy, Caddy, and Olds Toronado use the pickup coil with a yellow connector, and they use the igniton coil with red and yellow wires.
 
 
Buick and Olds (except Toronado -- and virtually EVERY parts book lists the WRONG stuff for Toronado) use the black pickup coil, and the ignition coil with red and white wires.
 
 
Pontiac uses a clear pickup coil connector, which is the same as the black one, only with longer leads -- therefore it uses the red & white ignition coil just like Olds and Buick ...
 
 
 
 
 
Originally Posted by Milan View Post
 
I have embarked upon a quest to comprehend the limits of the GM 4 pin HEI Ignition system. Here is a compellation of data I have collected from many sources across the web and from some of my old GM training manuals as I understand it.
 
 
The Stock GM HEI System Is a well engineered system for most street hod-rodding applications. The Stock GM HEI works well for the lower to mild end of the compression and RPM spectrum. All hype aside if you combo is well under 12:1 compression ratio and or rarely sees continuous heavy load 5,000 RPM duty you have nothing to gain from other styles of ignition unless you are going to mask other problems. The meat of it is this. The HEI Coil needs time and current to charge. If you limit either one of these you reduce the spark available to the cylinder. How much spark do you need? That is the Million dollar question that an entire aftermarket ignition industry is built upon. In reality, for a spark to initiate a jump of a spark plug gap it takes 10,000 to 11,000 volts. For it to maintain and complete the coil discharge process takes much less voltage, more along the lines of 3,000-5,000 volts. An inductive ignition system maintains the coil discharge time for a longer time than a CD System. The reason for the “multiple firing” at lower rpm of CD is not because it’s better than a single long spark but because the duration of the CD spark is so short it needs repetitive firing to ensure there is a spark in the cylinder at the opportune time.
 
 
A typical OEM 4 pin module is limited to 5 amps output so as to avoid overheating the coil and module itself. This is more than enough amperage IF you have enough time. If you do not allow sufficient charge time (High RPM) then you must push additional amperage through the module and into the coil to assure the coil is charged up enough to provide the level of spark you need. Most high performance aftermarket HEI modules are available in a 7.5 amp output version. Now it is important to realize this additional current may cause problems (excess heat) in the coil and there for it is wise to upgrade to a matched coil also. With these two upgrades there should be adequate spark energy through the 13:1 compression ratio and 6,000 RPM range.
 
 
There is a timing retard that occurs at a rate of approximately 1* to 1.5* per 1,000 RPM after full advance is reached. This is due to the Magnetic pick up trigger and not the module. I do not interpret this as a problem for most of us and I believe that high speed retard devices are becoming popular for a little more MPH. Hmm We have a built in device ….The reason the HEI system retards the total timing the way it does is this: as the pole piece spins inside the magnet (pick up coil) it creates an AC voltage signal (looks like a wave).The module uses this signal to trigger the coil. The module looks for the back side of the wave to cross the zero point to fire. As the pole piece spins faster it creates a larger AC wave and that larger wave crosses zero a little later and we have a later firing time (retarded timing).
 
 
I am not suggesting there is no need for other types of ignition. HEI does have its limits. I am saying that the Stock HEI will take you a lot farther than most people give it credit for.
 
Now if you need shiny things to go fast then spend away…….
 
 
Milan Atanaskovic
 
 
 
 
If you would like to purchase OEM-type weights and center plates, contact D&D Manufacturing, Inc., Memphis, TN (901) 458-3287 for more information.
 
 
Read more: http://www.highperformancepontiac.com/tech/hppp_0801_hei_distributor_ignition_system/viewall.html#ixzz2at72DJbP
 
 
http://www.stevesnovasite.com/forums/archive/index.php/t-199772.html
 
The 60 weights are equivalent to the 139 weights.
 
The 053 weights provide 1 degree LESS than the 139 weights.
 
 
So the weights aren't too big of a factor in changing the mechanical advance. Its the center plate that primarily determines how much advance is put out. So I compared the center plates that I found today in the junkyard do the ones listed on the chart this guy put together. Its pretty extensive, so it seems like the guy knew what he was doing. Of course I wont know for sure until I actually test these out. But here's what I came up with...
 
 
Center Plate 445 + Weights 60 = 19 degrees
 
Center Plate 445 + Weights 053 = 18 degrees
 
 
Center Plate 469 + Weights 60 = 21 degrees
 
Center Plate 469 + Weights 053 = 20 degrees
 
 
Center Plate 375 + Weights 60 = 26 degrees
 
Center Plate 375 + Weights 053 = 25 degrees
 
 
Assumptions:
 
Center Plate 445 + Weights 60 = 19 degrees
 
Center Plate 445 + Weights 053 = 18 degrees
 
 
Center Plate 469 + Weights 60 = 21 degrees
 
Center Plate 469 + Weights 053 = 20 degrees
 
 
Center Plate 375 + Weights 60 = 26 degrees
 
Center Plate 375 + Weights 053 = 25 degrees
 

Latest revision as of 14:34, 26 November 2023

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