Hello again all,

So I had a really weird issue today that I can't quite seem to figure out the cause for. So, in my truck was a factory FoMoCo distributor that had at some point been converted to be electronic instead of points. Given its age and the exhaust, cam, and intake modifications as well as future plans for the engine, I decided to replace the distributor, and to put in an MSD box to help with the low end response and help in the highway and winter conditions. After replacing the distributor with a Summit RTR model, I started the engine and it wasn't dramatic. I installed the MSD box a day later, and there was some initial knocking from the engine, but it soon sorted itself out and ran like an absolute dream. Did everything I wanted. Ran it later in the day (a few hours) and still beautiful. Then this afternoon I start the truck as it warmed up, she knocked like crazy, it was absurd and coming from both sides of the engine. Un-did the MSD box connections and ran it just the distributor, still knocking like crazy. Advancing/retarding the timing did nothing, anywhere from 0* BTDC to 20*+ BTDC. Swapped in the old distributor, and like magic the knocking was gone. I don't understand why this would be the case. Plugged the box into the old distributor, stilll no drama, running quiet as can be, except the small exhaust leak where the headers meet under the truck, which is totally normal. Running the same timing initial at about 10* by timing light. Top dead center confirmed via piston stop and a helper finger as well, so the dizzy is indeed at the correct location. I checked all the connections and wires for the Summit dizzy and installed the cap thing that goes over the wires on top of the dizzy the first day I ran the truck with the MSD Box and everything ran really well.

For reference, new MSD wires on the new distributor, presumably replaced or older wires on the old distributor (9.5-10K measured). Don't know if solid core becasue of the electronic conversion. Spark plugs on Summit dizzy combo were new gapped at first .045 then .035, and old gapped at .035. Issue persisted for all. Carb was fattened out in the idle circuit and leaned out, nothing caused a change in Summit dizzy. All wires for plugs checked out at around 135 ohms, didn't check the coil wire. Coil is also a 3 week old MSD Blaster 2.


Any ideas and suggestions anyone? I'm probably going to reach out to Summit and see if they will warranty the dizzy, or if they have any suggestions for what could be wrong with the dizzy. Thoughts? It seems bizarre to me and I am thouroughly baffled at this. Is is probably the new dizzy? Especially considering the old one is fine? Although acting slightly strange when cruising on the tach. Sweeping around a little intermittently, but not affecting performance. What do you guys think is happening? Any experience with the issue?

 

Well, IIRR that distributor is Chinese built and the same can be said for the msd box....personally, waste of $ IMHO as compared to having the oem distributor rebuilt.

 

It almost sounds like you removed/installed the distributors with the wires pre-installed? Did you make sure the firing order was correct? if you installed the new dizzy with what you thought was the correct firing order, and it wasn't, there's a chance you could have put at least one cylinder at a 45 degree advance (with another one being 45 degrees retarded) over the static timing which would knock like heck.

Please go back, and verify the firing order is the same between the two distributors.

If it is, it really sounds like the electronics on the new distributor is firing randomly when it shouldn't. Does it have any sort of externally controlled spark advance/retard?

 

I don't understand the first question about pre-installed wires. Both distributors are electronic units, instead of points. They came assembled and ready to plug in, just connect and fire up.

Both distributors are on the same firing order, I confirmed using the manual and looking at the new cap (All the plug wires are still in place and numbered, reading 1-5-4-2-6-3-7-8). I set up the old one using the previous order as I'd looked it up and put it on the wires, and that dizzy runs totally fine.

There is no external controlled spark advance/retard. Only thing external to the distributor is an MSD box, but that's just the spark amplifier. I'm tending to believe that its faulty electronics on the new distributor.

 

It almost sounds like a problem not related directly to the distributors. Maybe even temperature related. A poor electrical connection, (maybe a bad ground) could lose good conductivity due to a temperature change. Low voltage to your ignition system could be the culprit and maybe that happens when the temp drops... or rises depending on the connection problem.

Even water in the gas, although you said it worked fine once while driving, so not that likely.

 

Any kind of settable air-gap on the electronic pickup in the distributor? Sounds like it's firing incorrectly.

 

IMHO, this is directly related to either the dizzy and/or MSD box..... either the triggering system and/or the voltage breakdown caused by either internal heat buildup or crappy e-components. IMHO, pull it, have the oem distributor reconditioned (yourself or a pro-shop), re-curve it and use blue streak ignition points/condenser..... whatever beand of cap you buy, make sure it fits very snug and use THAT mfg's rotor to ensure a perfect match.
As far as points go....You will have to excuse me a little here, but, what is more reliable than points......certainly not the more popular & common “e-box replacement kits”. Yes you can hear people state "It runs so much smoother/better than when it had points"........in each case that an individual said that in my presence, they had very little knowledge about points and the ones they were running were- old & tired or inexpensive aftermarket replacement units or the individual (including professional mechanic) was unfamiliar with not just setting the gap to OEM specs, but setting the dwell & initial timing to what the engine likes.

But let’s look at the OEM ignition system from the early 60’s….
Original Coil Voltage: 20,000; by the end of the 60’s 40,000 volt high performance coils were common…..by the 70’s 50,000 & 60,000 volt coils were easily available & is what we have today. Did we really gain all sorts of HP/TQ with all this extra voltage…….no, what we were able to gain was stronger support (if you will excuse my terms here) for higher RPM’s- specifically in the 6,000+ range…..enough to power NASCAR engines in the 8,000 rpm range at 200+ mph!

Points were used in NASCAR up through the late 1970's, running speeds of 200mph+.........Cale Yarborough did lose a race one time because the ignition points broke. In a street application, if you look at the data very closely that is provided by these more common e-box companies, in street applications (where max power-band RPM is around 6000), when the standard dyno deviation is removed (5% standard per every dyno mfg) there is less than 1% improvement in performance. Further testing by independent aftermarket DIS (direct ignition system) manufacturers verify this through their own testing- there is little gain over an ignition points system until you reach 4000 rpm…then you begin to see a slight sustainment of ignition delivery above what points can deliver but it doesn’t even begin to compare to what a “modern”, real e-based system can & does deliver in a real world street (and race) environment.
I am not promoting this product but their analysis is very accurate of the misleading <acronym title="Page Ranking">PR</acronym> docs pertronix & others have…... Compu-Tronix. Electronic Ignition Systems link: http://www.compu-tronix.com/MightyMo...risonGraph.pdf
The other item is, in a street vehicle, if you wait to see improvement until 4000+ rpm, the race is over and these e-box “conversion kits” have literally the same design limitations as the “conventional points”- because they are essentially using the same delivery system (rotor, cap, wires, etc.) and they are subject to the same inherent design impactors of which there are numerous….including ozone that is produced within the cap…..none of this has by miracle “disappeared” and in fact when compared in true recorded data-frame analysis, the benefit will be gone by 5800 rpm and the loss, although slightly less, parallels that of points. In racing conditions that could very well make a difference, but in a street application, you could literally change brand of fuel and see that level of improvement or degradation. The e-box/e-distributor aftermarket industry- a lot of <acronym title="Page Ranking">PR</acronym> documents which physics does not play any part!

Very good quality ignition points/condensors are available and when set properly, are very reliable and provide excellent performance. There have been no less than 5 people who I personally knew were going to get e-boxes, then I had them get a good set of points/condenser, a high voltage (40k+) coil, and installed them showing them specifically how to do it......the engines ran smooth and strong. One person did end up buying an e-box, why, because he said he just got tired of not being "cool", after spending $500 for a distributor, etc (he went “Popular” high end), a year later (when he asked me to help him fix something) he admitted, it was a waste of $...it didn't run any better than after we put the points in.

While many state the positives of e-boxes (and there are certainly many positive attributes), there are conditions which reduce an e-boxes/e-distributors effectiveness & reliability....to start with the circuitry and handling (container vessel shipping) of it from China (which is where 90% of the more common/popular e-box company's products originate). Any aspect including temperature control, static safeguards, moisture can & will cause both detectable and undetectable damage which may not show up until after you have subjected the installed component to real world vibrations, heat, cold, moisture & grease/oil. Yes, all of these damage e-components, but the systems (based upon a variety of factors) are suppose to be prepared to endure these exposures but that is based upon many, many assumptions. Including proper handling & q/a.......given all of the 3rd party involvement in the final product, it is unrealistic (IMHO) to believe that e-boxes have an increased reliability as compared to their mechanical-based counterpart. In terms of “Dwell Control” I won’t even go into that in detail but I will say, what the “kits” provide is a joke…..you can actually get more control over the dwell by having an understanding of how to set timing versus dwell setting with points than the most popular e-box conversion kits can provide…..which makes for a very smooth running engine- this is not just IMHO, but well known among the "higher quality" aftermarket engineers whose systems reflect this ability to "tune"!
If you need to say I got rid of my points…ok, that’s fine, but if you are really serious about actually upgrading the ignition system then do so……although it has been scrapped by the OEM’s in favor of more advanced, effective systems, there are aftermarket DIS units (yes the same as Ford used in the 90’s & developed by Porsche in the 80’s) whose cost is within reach of most buyers and will actually perform as stated or DUI units are very good as well.

and yes, points do require a periodic adjustment.... mine, about every 8-10K miles...….. as I laughlingly replied to a gent (self proclaimed expert) who insisted at a car show that "use of points was not only inefficient but required constant maintenance"....I replied very publicly, " if you or your mechanic are so detached from opening the hood of your car that you consider it an inconvenience to periodically check and adjust the points, such as with at each oil change, the likelihood is that your car is not even safe for the road".

Ok, I'm done now...……...

 

Good thought!!!!!.. Didn't they (Mallory) use to have the "Unilite" ignition module..... they either worked or they didn't.... being in the "dark" was more common than not and the gap setting was insanely important!!!!!

 

Good thoughts, Beechkid... however, I tend to disagree slightly on the reliability of points... for one thing, they will take out the upper bushing in the distributor eventually, leading to the dwell walking all over the place especially with the vacuum advance moving the base plate around under it. Been there, done that with my Highboy. Pulled the vacuum advance line just to be able to get it to run well enough to get to work one day. Starting with a reman'd distributor would lead to better results, but only if they actually replaced that upper bushing

A Pertronix unit is often a band-aid when that bushing goes too far... it certainly solves the problem without actually "fixing" the problem

I ran a Duraspark, and later an MSD 6AL and a higher-voltage coil all on a 1976 (small-cap) Duraspark distributor with my last 390 in the highboy.

 

Points mainly get a bad reputation today because 1. peeps try to run them in a completely clapped out distributor they found in a junkbox or something. You can see this very clearly on an ignition scope. They will never set much less hold the correct dwell angle, plus the usual sticky and/or erratic wallered out breaker plate. 2. Crappy foreign el-cheapo points and condensers.

A properly setup and adjusted points distributor is as reliable as anything, and let's face it, collector cars and trucks aren't usually daily drivers. Back in the day a twice a year Tune-Up was the norm, but today 8,000 miles represents years and years for many people.

A Pertronix Ignitor or electronic points replacement module is less affected by a worn out distributor, but the ignition defects are still obvious on a scope. A fresh tight distributor with good bushings &c will idle and run much smoother and more powerful up and down the RPM range regardless of what actually fires the plugs.

 

AGREE!!!vall they way as well.... I'm lucky, my distributor was rebuilt by Borg Warner when it had 210k miles on it (in 1985/6 when I did the ground up on "her"...….. I figure she should out live me now!!!!!!

 

I agree on all points (ha hah..... ). A well-setup points dizzy is equally as good as most electronics, at least for near-stock vehicles.

The one thing I will say, and that's it from me, is... to support a higher voltage coil, points start to have issues with that too, as in the "snap back" (hysteresis) will overcome the condensor and start to arc the points... higher RPMs also lead to "points float" just like valve springs which of course can be worked around as well.

Two sides of the same coin, we all just want our FEs to run perfect all the time.

 

If you dig into the manuals contact points had all kinds of details for a setup in a Tune-Up, it's easy to see why solid state was so quickly adopted.

A spring scale was necessary to measure the tension on the rubbing block arm - about a pound was the spec on Fords. That's why there are two nuts on a set of points, by moving the spring fore or aft the tension is increased or decreased. If the spring tension was too low, the points would tend to bounce at high RPM and cause misfire. If the tension was cranked up high, stuff a piece of rubber vacuum hose behind it, etc., the ignition would fire reliably way up high (drag racing) but they would wear out right away and tend to trash the distributor cam lobes.

 

agree! But this was "common knowledge"...… literally, just like cutting grooves in brake shoe linings to channel the water out of the drum (this used to be taught in the ase schools but has long disappeared from the text books as well.