• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

    So with that I ask that anyone with a question about one of our build ups or a general tech question to please use the forum as it was intended. I am absolutely available by telephone to answer your questions as well but at times may direct you back to our website to better field your question or questions. Most other private messages I will be glad to answer for you.

    Thank you for your understanding.

    Jeff Ismail

Ignition System Performance Upgrades

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Let's post any and all ignition system upgrades, performance mods, workarounds, etc. In this thread regarding ihc vehicle applications. Depending upon level of interest, we May spin off various topics into their own thread at some point.

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Ok, here's a little ignition upgrade I'm currently working on...

This system is going to consist of:

1) mallory series 25 dual point distributor.

8/6/08 edit!! Do to the fact that dave's collection of msd 6 boxes is in storage in portland, and the fact he's gotta spare mallory hyfire6a box on hand, we've decided to go with the mallory box first. So I've corrected this post to reflect the change in parts. The msd and the mallory boxes are virtually identical in actual operation, I've wired the mallory with quick-connect weatherpak connectors so it can be interchanged very quickly with the corresponding msd unit once I have one on hand.

2) mallory 6a series cd ignition box.

3) msd in-cab adjustable timing control.

4) msd blaster ss epoxy e-core coil.

Here's some background on "why" and "what"...

This project is simply an ignition system experiment since I have all the components on hand. It's a mixture of oldskool low-tek (hi-tek back in the day!) and "current" tek.

Gearman dave acquired the sv-application mallory dual point distributor at the Binder Bee and gifted it to me! He is enamored of those sparkmakers since his roots belong with 'em. This one is mechanical advance unit only and is a near-virgin. I've gutted it out for inspection and lubrication and found it in perfect condition. The quality of the internal parts and workmanship is head and shoulders above any oem distributor and these units were the gold standard for engine performance in the golden era of the American v-8! These units are still available from mallory though they have been eclipsed by the "unilite" series opti-electronic trigger distributors. The mallory distributors are one of only a very few dedicated replacement distributors available for IH I-4 and sv applications.

The msd 6 box is also considered the standard ignition system upgrade regarding aftermarket performance items. It can be triggered by virtually any known distributor system, is a true capacitive discharge (not inductive!) add-on, and is compatible with virtually any ignition coil, oem or otherwise.

Dave has boxes full of msd 6 units left from his nascar days, so I dam shore ain't spendin' much cash on these toys! These are units that were returned to msd for "re-cycling" after every long-track race, since they were run in matched pairs (a back-up ignition system is sop in nascar stuff). They are potted inna clear material to allow visual tech inspection since all cars are required to use the same ignition system components.

An adjustable ignition timing control is an add-on for various msd ignition boxes. This is an in-cab mounted control head featuring the ability to "electronically" vary/change ignition timing in a dynamic mode. Especially useful for towing applications involving many varied changes in elevation and available fuel octane numbers across the country.

The msd blaster ss coil is also a leftover from a previous "failed" experiment...but it is a perfect match for a msd 6 series spark box which loves to pump juice into a low primary resistance transformer!

To go with all this will be a fresh set of autolite 85 plugs gapped to 0.045" to start with. That'sa known quantity and the plugs are verified as being the correct heat range for my current motor setup.

The baseline ignition system for this sandbox operation is a verified perfect Holley oem points distributor with a m/y 1973 emissions advance curve, that has been converted to a pertronix ignitor (not an ignitor II). This unit fires an oem-replacement ignition coil capable of producing 22kv+ as verified on a scope in open-circuit mode. The p-tron is set to provide a dwell factor of 30* (actual 0.030" trigger air gap as spec'd with the pertonix-supply "tool") with a dwell variation of less than 1* indicating an excellent "runout" factor for the distributor shaft/mechanical advance combo.

And in the future, I plan to work up several similar systems using various other distributors and components. Idea is to give some real-world feedback regarding a side-by-side comparison of "parts" without all the marketing smokeblow that is used to hype this stuff in the retail world. And for consistency, all this stuff will hang on the same motor unless it expires first!
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Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Next we'll get into the “why” and “how” of the components for this exercise. First off...the model 25 mallory dual point distributor.

This aluminum body part has been on the market since the mid-60's in one form or another. This particular unit is “mechanical advance only” and has no provision for changing over to a vacuum advance control. All components are purpose-design and are much improved in both design and materials as compared to any oem distributor, very high degree of quality and workmanship.

In order to allow space internally on the breaker plate for the extra point set, the condenser is moved to an external location. The advance curve is easily “adjusted” as needed using only a screwdriver even though the curve is pre-determined for the correct engine application at the point of manufacture.

The cap and rotor were manufactured from bulletproof materials back in the day, and are still somewhat more robust than any comparable aftermarket part.

Most folks consider a breaker point system to be somewhat outmoded when compared to available electronic trigger systems, but there are advantages to the use of a dual point system still. However, this distributor is capable of being converted to either a unilite (opti-electronic) or mag trigger if desired.

Because of the lack of supply of a distributor drive gear in the replacement parts world, the IH application of all current mallory distributors are supplied without a drive gear. It's necessary to install a drive gear from a donor oem distributor in order to make this a drop-in replacement. And...it May be necessary to r&r the gear a few times, adding or deleting shims to bring the end play of the distributor shaft into spec, this will vary with the dimension of the drive gear selected.

Dual point distributors were developed by both oem manufacturers and the aftermarket to solve a problem referred to as “point bounce” or “float” experienced with engines turning higher rpm than originally designed. It's also a methodology for increasing inductive ignition system “dwell” which is not achievable with a single point distributor and most electronic-trigger systems. However, due to the fact that the IH motors are more characteristic of tractor units than a chryfordrolet, point float due to engine rpm is not ever a consideration!

The mallory unit under discussion here has just been completely disassembled, cleaned and all inspection points have been attended to. The spec'd point “gap” has been set using a thickness gauge. Once the unit is installed, each point set will be insulated in turn, and the opposite set will have the dwell verified with a dwell meter. Once the dwell is verified for each point set, then the “total” dwell May be read on both a dwell meter and on the oscilloscope (somewhat more accurate).

Pic shows the dual point mallory side-by-side with another distributor project which will also be a part of this upgrade experiment. That one is a delco points distributor converted to a pertronix trigger (not a pertronix II), along with a re-curved mechanical advance system with a vacuum advance lockout.

I've not installed the drive gears on either unit yet, I'm waiting for the arrival of a distributor “shim” kit from msd so that each unit can have the gear selective fit for minimum end play resulting in much more accurate ignition timing from idle to red line. That will pave the way for the adjustable timing control component which will accompany the msd 6 box.


Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
This is another shot of the mallory dual points rig, internal view. Both sets of points May be seen. These points are specialty items designed only for these distributors. Extremely high quality materials, phenolic rubbing blocks, and a lubrication “pad” which insures long point gap life between adjustments.

In the past, mallory has offered similar aftermarket replacement breaker point sets for many oem distributors, but currently there is little market for those items.

Because the msd 6 box uses the breaker points only as a “trigger” or switch, point life is greatly extended as current flow across the point sets is very minimal. And if the gap does not change over time, then timing stays within setpoint, same as for an electronic trigger.




you are providing me with late night amusement....

As you state, mallory dual point distributors were (supposedly) to solve the "problem" of "point bounce". But, "they" (as you know) were "talking" about "car" engines and 6000+ rpm....

So, my feeble brain does not "comprehend" point bounce on an sv v8 IH engine with a max recommended rpm of 3600...

Do you have an IH "race" engine that I am not aware of?

Wish you luck... Robert

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Naw Robert...the mallory sparker is just gonna serve as a highly accurate trigger for the msd box. Otherwise, I got no use for breaker points in any engine application in today's world, there are too many ways to avoid the use of points!

The mallory distributor mechanical tolerance is extremely tight, eliminating any "runout" or dwell/timing shift as rpm increases/decreases vs. Engine load. And even though the mechanical advance unit is below the breaker plate, the adjustments are accessible through designed-in ports making quick and ez advance curve tweeks doable.

If it turns out that I keep running the mallory, it will be converted to an electronic trigger but retain the classic mallory appearance. All that will depend upon "which" of several ignition system combos I anoint "the one"!

Any IH-app distributor which was originally speced for an egr motor has a curve which is not optimized for the elimination of egr. I've been playing with re-curved distributors for some time now so that I can poorboy a curve using methodology available to anyone with a dial-back timing light and patience. I don't have access to a distributor machine which could make this exercise a bit more productive! But since I'm on welfare, I got time to scruu off with needless and useless stuff!

And the ability to tweek base timing for fuel and altitude variations when towing, by using the msd toys is a consideration outside which distributor/trigger is used. Msd is not the only source of that kind of stuff, crane, and mallory also have similar components. But the msd box is free, the distributor is free, and I have the coil (I actually have several assorted coils that are gonna be used in this little project), the only additional item I need to actually spend cash for is the timing controller.

Future project distributors are gonna consist of:

1) delco/pertronix combo with "adjustable" advance curve (easily accessible and fairly tight in the runout department).

2) Holley/pertronix combo with a seat-of-the-pants advance curve re-calibration (currently installed).

3) Holley governor distributor converted with a magnetic trigger (homebrew).

4) #1 distributor in this list converted to a crane xr-I lobe sensor electronic trigger. There is not an xr-I conversion available for the Holley points distributor.

This is a project...not a git 'er dun deal!

If I was looking for git 'er dun, I'd continue using what I personally feel is the most cost-effective and best performing system, a crane xr3000 optical trigger inductive system which also uses a primary circuit "amplifier" though it's not a cd system. This would be installed inna "tight" Holley distributor with minimal end play.



thanks for the reply to my short, cryptic reply. I guess I should add a little info / background.

The only reason that I know anything (a little) about the mallory dual point distributor is because my corvair mechanic (late 70's - early 90's) had one. But, he did not put it on his personal corvair (also, a test bed"; he liked to "do projects", also) that I was aware of.

He "supported" / "sponsored" a guy who raced a corvair in scca races in the early 70's. Maybe it was used on his car. From what I recall, my mechanic was a "proponent" of building an engine that could complete a race and go from there as opposed to building the "hottest" engine you could and breaking it after a number of laps. He also campaigned a aa fuel dragster in the 60's.

What he (we) did in the interest of a "tighter" distributor was to use the mod of another racer -- put two "bushings" in the distributor housing. Machine the housing to accept a sealed bearing in place of the original "oil-lite" bushing and put an oil-lite" bushing in the base of the housing (we sent distributors to him to be modified.).

But, one issue did occur on my corvair after a number of years and many miles. I pulled the dist for some reason and looked at the brass distributor drive gear on the crank and it was worn. Actually, the "teeth" on the gear were almost "knife sharp" (and almost "gone") when removed. So, I had to replace the dist drive gear. I also went back to the stock (one bushing) dist housing.

I did not even think about the different distributor curves for egr / non egr distributors until you mentioned it.

But, given all the different variations (shafts (plates) / cams / springs . Weights) for corvairs, I can only guess at the number (100's?) of distributor curve variations that IH came up with.

And, I assume it is hard to come up with the right pieces (in good enough condition) to "back build" an egr Holley distributor to a non-egr Holley distributor.

I also recall trying a "dist kit" (cam, springs, weights iirc) for the corvair distributor that converted the dist to "all" mechanical advance (no vacuum advance). I "did not like the curve" and went back to the stock setup.

Does the mallory have enough "total advance" in its mechanical advance system?

Good luck on your projects.

I probably will not adapt any of the changes, but I will enjoy reading about the results -- and knowing that the knowledge will be here if I decide to make any changes.

Greg R

I'ma watch'in this thread with a magnifying glass and tape recorder:gringrin:
any way, as I'm interested in all of them, I'll pay particular attention to item 2.

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Overlooked your response here Robert, sorry!

I fully understand what you are saying about accelerated distributor drive gear wear! There is much info available on that subject for chryfordrolets, most especially from mallory and msd! Different gear materials used for different camshaft materials and designs. And the gears are changed out at maintenance intervals on the race motors as you described!

Doesn't appear to be a problem on IH stuff since the cam material and the oem distributor gear material are "compatible".

This particular mallory unit though showed a strange issue with the shims between the gear and the body (that is where the end-play is set). That tells me that it was run in an engine that did not have the oem guide bushing installed in the block just above the oil pump drive end! The side-thrust on the distributor shaft is exorbitant if that bushing is not present and that is a common occurrence I've seen on many IH motors! On a Holley distributor, the lower shaft bushing is eaten away within an hour or so of operation, allowing the shaft to "cock" in the housing and the mechanical advance unit to eat on the interior of the housing!!!

Originally, I thought that the cast iron Holley governor distributors were anti-friction bearing design, but they are not...simply a much more massive and well-supported oilite bushing set-up, much more rugged than the standard Holley units used in light line stuff.

That distributor "curve" kit you described for the corvair is exactly the same thing as the kits I buy locally! For the delco units, that is a very easy swapout, I have one now that is going to be part of this series. I'm still waiting for the drive gear shims to arrive from msd so that unit can be completed. I can't remember exactly...but it seems the corvair distributor was so "short" it used only a single bushing in the body??? The sv distributor apps for prestolite, delco, and Holley (as well as the mallory) use two bushings, one at the top, one at the bottom.

Once I get to the point of installing and testing the delco, I'll post the pics of how to play with the "curve" on the delco. That can be done without even removing the unit from the engine! Doing the same onna Holley is a bitch since the distributor has to be disassembled initially, but the same assortments of springs May be used on the Holley as is used for the delco.

Also...the mallory is much more robust in the bearing/bushing interface, and the lubrication scheme for the advance mechanism is far more advanced than the oem-type. The oil "feed" hole at the bottom of the body is twice the diameter of an oem distributor hole. One reason the delco distributor is so bulletproof for an sv motor is the fact that it has an external "lubrication" port that has a periodic maintenance schedule.

In the distributor identification thread we've got going in this forum, I allude to the "different" curves that are spec'd for various IH sv engine applications. So far, I've accounted for about eleven different curves that were spec'd, but those are related to the oem distributor part number and are not related by "year model" or platform. So the starting point for determining what would be an non-egr curve would be picking out an non-egr distributor from an IH parts list and comparing that with the specs in the appropriate service manual.

But folks who deal in "curving" distributors know how to set 'em up and all have their own "secrets" developed over time, that's real ez to do if ya have a distributor machine! No doubt your corvair guy had that subject down pat! I used to have the same thing in my head for chrysler "b" motor distributors back when I raced that stuff in the 60's. Wish I had written that down somewhere but I was young and stupid and thought I knew everything at that age! So now I get to start over using technology to remember stuff!

By the way, no doubt the finest car I ever owned was a '61 corvair! Whatta great ride (had a paxton/mcculloch supercharger on it for awhile, the precursor to a turbo-spider!).
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Thanks for the reply -- interesting stuff.

Yes, my corvair guy had a distributor machine (from the 60's?). I watched him "run" a couple distributors on it over time, but I did not really "understand it" -- though he tried to explain it. He was "old school" enough that he had a "hand-powered" arbor press (correct term?) -- to press gears off shafts; press out bearings, etc -- he was a pretty "big" guy. His son probably still has this equipment.

Yes, the shaft on a corvair distributor is probably shorter than a v6 / v8 -- and it goes thru a "boss" in the rear housing to "access" the oil pump. But, the real reaon there was only one bushing is probably the GM "bean-counters"....

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
All the "mts" service reference series show the use of a distributor machine in the shop for performing ignition service. It was much easier to just pluck the unit outta the motor and chuck it in the machine for points changeout and dwell setting (and verification of the advance curve) than fight it leaned over the radiator!

Then the unit was simply stuck back in the hole (after verifying that the lower drive support bushing was in proper position), and the base timing set.

Just a few weeks ago a good friend gifted me a harbor freight bench-mount arbor press which is perfect for servicing these units! In fact, today I started rigging a fixture specifically for removing the IH drive gears from these distributors. I'll post a pic once it's mounted and functional. This one will make 2000psi.

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Here's the capacitive discharge ignition box we're now gonna use...a mallory hyfire 6a.

This unit is virtually identical to the msd "6" series boxes, main difference is the construction of the circuit board and heat sink interface.

This one had been previously set up for a magnetic trigger distributor along with weatherpak connectors installed to make it a "quick change" operation should it ever fail and a backup unit quickly swapped in.

So I changed the wiring back to a "points trigger" and made up a quick connect harness for the truck so it can swapped out easily also.

By using this item, along with a "low resistance", high turn ratio coil, a spark plug gap of 0.045" will be tried initially which will take advantage of the increased "voltage available" on the secondary side of this system...it also has multi-spark capability up to around 4000rpm...at which point these motors become real asthmatic anyway so a rev limiter is pretty much useless, they are self-regulating!


Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Finally completed the first round of the ignition system upgrade last night. The results??? Completely amazing to even a jaded old bastard like me!

Here's the setup right now:

1) Holley distributor in excellent condition loaded with a pertronix 1481 conversion trigger module. Oem advance curve in this one, never tweeked.

2) msd blaster ss "low resistance" e-core ignition coil. These must be used only with a cd ignition box if tied into a pertronix trigger. Otherwise, the pertronix will fry in about 30 seconds.

3) mallory hyfire 6a cd add-on ignition box.

4) all wiring connections are made using weatherpak components to allow "quick change" trade out of distributor, pertronix, coil, other brand cd boxes, breaker point conversion "back-fit", etc.

5) new autolite 85 (verified correct heat range through insulator color observation. Plugs are gapped at 0.045" to take advantage of the increased secondary output made possible by using the cd system and a suitable coil.

6) accel ss 8mm secondary cables installed about 16 months ago.

7) "power-timed" several months ago for optimum performance/economy. A/f ratio verified on exhaust gas analyzer at that time. Got no idea what the base timing is right now and don't really care!

With the previous inductive ignition setup (oem-spec coil with pertronix trigger) the engine started instantly when cold at any ambient temp (including sub-zero). Based on engine analyzer/oscilloscope analysis, the engine and ignition were in perfect tune.

The current level of ignition system upgrade has resulted in 1"hg additional vacuum and after re-setting the idle mixture screws, 2 additional inches total have been realized. Curb idle speed increased by 150rpm so that had to be changed as well. Cold and hot start is even better, it busts off now with nearly no starter rotation. Overall idle quality is greatly improved, even though I thought it was perfect previously!

The carb was set up with ragged edge lean jetting. When towing, the two stage power valve is open nearly all the time, resulting in maximum fuel economy under severe load (6500lbs.) and that corrects the lean jetting. With the much more complete combustion afforded by the cd ignition system and wide-gap plug settings, the lean surge at 30 mph when not towing is now eliminated.

No fuel milage numbers with this setup, we'll run it about 250 miles on Thursday and what improvement if any is noted.

My engine analyzer won't trigger from the cd setup, all the leads are direct connect and it comes from an era vastly removed from the "tech" of this system. It will trigger from an inductive system using the pertronix and I do have the numbers from that setup. Lyle's peerless analyzer is somewhat later model than mine, so we'll run this motor on it and see what we get. I'm mostly interested in the actual output kv potential for this system as compared to advertised claims.

So right now, I'm saying this type system has a much in the way going for it regarding "bang for buck".


Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
And here's a shot of the msd ss coil mounted on the bracket. This bracket will hold the oem coil in an upright position and provides a bit more air circulation around it also allows ez access to the terminal connections.

Inside the split loom, are the complete oem wiring connections to quickly convert back to an oem coil, bypassing the mallory box by simply disconnecting the weatherpaks and letting 'em dangle. In the glove box is a baggie with polarity-specific pigtails with quickconnects to make the swap.

Both the mallory cd system and the msd system use a switched b+ feed to power up. The "resistance" wire" or ballast resistor (if a workaround has been used) feed to the coil is eliminated. The coil is now powered by the cd box, not the b+ feed. The "new" primary voltage is a nominal 430vdc, not b+!


Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
Enjoyed jawwin' with ya yesterday in person!

So that's a big hurdle for ya, the mallory sparker is legal for what ya wanna accomplish. I'd print the info regarding the carb number (and any of the rest of the ignition stuff) and carry a copy with ya when ya are finally able to attempt the smog dance with the smog nazi.

Here's a pic of a recent rebuild I did onna sv unilite (it had 3/16" end play which was disastrous!!). As ya can see, it has no exemption number on the module...that is why I suggested that you check yours!


Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
really enjoyed this write up:thumbsup:
The lonmiester returns to the pardee!!!!

This deal ain't over yet lonnie! Wait 'til we git to that crank trigger dealybob we got going for the stroker 152:


You know me...I don't git inna hurry 'bout nuthin' (except when it involves grub).

And...I've got a couplea very cost-effective modernizations of Holley distributors in process now that will allow the same unit to be used with either a carb or with some efi conversions. One is nearly ready to ship down to Jeff at ihon to try out on his efi whitescout.


Thank you for the welcome.

Interest in your write up was based in part on my having done the same upgrade as you describe. I have installed a msd and hyfire cd units (and dizzy upgrade including recurve) to my 63 and 62 scouts respectively. Performance gains were just as you described and so it should come as no surprise that I plan to follow, with interest, what other upgrades you have in mind.

This weekend I will be upgrading system plug wires from the standard 6mm to msd 8.5mm. I expect there to be little performance gain and will certainly let you know anything to the contrary.