Nailhead Distributor

[RivNut]

Has anyone heard anything about this unit?  HEI nailhead distributor from Speeday Motors.

 

https://www.speedwaymotors.com/Speedway-Motors-Buick-Nailhead-V8-HEI-Distributor,443608.html?utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gad_source=1&gclid=CjwKCAjwoa2xBhACEiwA1sb1BDPyh5o1TDkYuqRWE3VIc8xVzHRccAbOA_bN_Zl8lZ8LqVb4Ib1VvxoCb-cQAvD_BwE

[NTX5467]

How much different are the electronics than any other replacement HEI unit?  Looks pretty normal to me.

 

NTX5467

[drhach]

This is what Centerville says on their webpage about HEI distributors. 

 

"The HEI units are just plain ugly and not worthy of the a beautiful Buick engine. I call the HEI the "Elephant Mans Head Distributor" They can also cause firewall clearance problems. "

 

[Seafoam65]

There's no reason to put an HEI on a nailhead. They are too large, ugly to look at and are less reliable than a stock distributor with a Pertronix conversion kit installed. This is only my opinion of course........other opinions may vary.

[Pat Curran]

I converted my 1971 Monte Carlo to a Pertronix unit 24 years ago and it has been flawless since.

[Ben Bruce aka First Born]

I believe, RivNut, the answer to your question is no.😁

 

  Ben

[NTX5467]

10 hours ago, RivNut said:

Has anyone heard anything about this unit?  HEI nailhead distributor from Speeday Motors.

 

https://www.speedwaymotors.com/Speedway-Motors-Buick-Nailhead-V8-HEI-Distributor,443608.html?utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gad_source=1&gclid=CjwKCAjwoa2xBhACEiwA1sb1BDPyh5o1TDkYuqRWE3VIc8xVzHRccAbOA_bN_Zl8lZ8LqVb4Ib1VvxoCb-cQAvD_BwE

Personally, we know that the particular vendor had to get the HEI from some place, as they normally don't build such, just re-sell other people's stuff.  Which is why I wondered what was so special about that item.  The HEI, like any other GM distributor, can be re-curved as needed.  Add an adjustable vac adv can and that part is covered, too.  

 

Their dialogue is pretty flowery.  The stock HEI GM coil will fire a .075" gap, with good plug wires, or even a bit wider.  Put a good aftermarket module with that and things are better than factory.  Yet the prior points systems would fire a .040" plug with no issues.  Which makes the only reason for an electronic ignition the reliability and spot-on timing of each plug firing.  Which the various levels of Pertronix can supply under the stock ign cap.  IF you wire it inconspicuously, nobody's the wiser.

 

In theory, if you add a Pertronix unit, use some good OEM-look magnetic-suppression plug wires, and add Iridium spark plugs into the mix, that should make an "Ignition system for life".  As modern OEM Iridiums should last between 100-150K miles.  Even the prior "single-Platinum" OEM plugs were rated at 50K mile change intervals.  Provided the fuel system doesn't have some richness issues.  At 3K miles/year, how many years would that be?

 

Enjoy!

NTX5467

[arnulfo de l.a.]

Daves small HEI. Uses the original distributor and works flawlessly. Price on par or less than the aftermarket Hei’s and most importantly HE STANDS BEHIND HIS WORK .

[EmTee]

I thought maybe it was a DUI distributor https://performancedistributors.com/product/buick-nailhead-dui-distributor/ , but the price implies that the Speedway item is a lower-cost 'knock-off'...

[60FlatTop]

Test your operating secondary voltage on your car as it is now and see how much High Energy you may be lacking. Your voltage is probably running 3,000-4,000 volts now. And if you are up in the 4,000 voltage you might be running a little lean. Fix that first. Ohm's Law should be your guide.

 

On the aesthetics of a Nailhead, I have always run a 401 air cleaner. I bought a stock one but it hid my good looking engine.

 

I cringed a little when I read Speedway Motors but it was just a small vascular event and probably good for my circulation.

[NTX5467]

No matter how much POTENTIAL voltage the coil might produce, it will only produce enough to fire the plug.  Normal coils would usually do 30KV, which worked well for us for decades, with 11.0+ compression ratios.

 

NTX5467

[Seafoam65]

My biggest gripe with HEI ignitions is that the spark is so hot that it burns out plug wires

and ignition rotors. My Dad bought a new 79 Camaro and it had a plug wire with the spark jumping through   the wire to the firewall when the car was 3 days old. Very common for 

the ignition rotor to get a hole burned through it with the spark jumping down the distributor  shaft instead of out to the plug wires.

Edited April 28 by Seafoam65 (see edit history)

[Ben Bruce aka First Born]

1 hour ago, Seafoam65 said:

My biggest gripe with HEI ignitions is that the spark is so hot that it burns out plug wires

and ignition rotors. My Dad bought a new 79 Camaro and it had a plug wire with the spark jumping through   the wire to the firewall when the car was 3 days old. Very common for 

the ignition rotor to get a hole burned through it with the spark jumping down the distributor  shaft instead of out to the plug wires.

 

 For what its worth, I have never seen such an outcome.   Never have I had such happen.   Just my experience from many thousands of miles.

 

  Ben

[EmTee]

8 hours ago, Ben Bruce aka First Born said:

 For what its worth, I have never seen such an outcome.   Never have I had such happen.   Just my experience from many thousands of miles.

 

Ben, are you using the OE spark plug routing (under the cover) on your car, or are the wires out in the open?  7mm or 8mm wire?

[60FlatTop]

I have seen the arc through the rotor to the distributor shaft on a Chevy truck I had. I couldn't diagnose the problem but a friend picked up on it right away from previous experience. It may have been an aftermarket rotor. I lot of things have to come into play to get the problem.

 

I have an inductive KV meter for the secondary side that I have used quite often over the past 30 years and I had an Allen scope prior to that. I can't recall seeing anything more than 4,500 V on anything I worked on.

 

If you pull the coil wire and let it hang to disable the ignition the coil will put out all it has, maybe even blow itself out. I always ground the coil wire to deduce the total resistance if I do something like that just to prevent another problem.

[EmTee]

HEI became standard equipment on GM cars in 1975.  A few months later I can remember several 'new' Pontiacs being dropped by a tow truck at my friend's father's auto electric shop for a no-start condition.  The first couple required the usual diagnosis, which identified a burned-through rotor.  Repair of subsequent victims took all of 5 minutes with the majority of that time spent removing the air cleaner to expose the distributor.  I don't know why Pontiacs seemed to fail more frequently, but I really don't remember having more than possibly 1 or 2 of any other GM brand.  The aftermarket apparently solved the problem, as we never had any 'comebacks' once the OE rotor was replaced.  The next weakest link were the OE 8mm wires...

[johnrex]

I've have a Petronics in my '64 for over 20 years, no problems.The HEIs in the various GMs that I have owned were a lot more problematic; failed modules, pickup coils, rotors, etc. and these were all OEM parts. Also the quality of replacement modules is not good even if they say Delco.

[Ben Bruce aka First Born]

1 hour ago, EmTee said:

Ben, are you using the OE spark plug routing (under the cover) on your car, or are the wires out in the open?  7mm or 8mm wire?

 

 They are in the open as of now.   Just have not installed the cover after installing the 7mm wires from Brillman.

 

  Ben

[NTX5467]

14 hours ago, Ben Bruce aka First Born said:

 

 For what its worth, I have never seen such an outcome.   Never have I had such happen.   Just my experience from many thousands of miles.

 

  Ben

I can say the same with over 700K miles on my ORIGINAL HEI in my '77 Camaro.  I always gapped the plugs at .045".

 

Now, I did see where the spark jumped from the bottom of the coil to the rotor, putting a hole in it when the carbon terminal wore away.  That was common on higher-mileage motors, it seemed, and a "go to" place to check for drivability issues related to the ignition.  That carbon piece was available separately for about $5.00, back then.

 

In an old Petersen Pub. Co. book on ignition systems, circa late 1970s, it was stated that the HEI was designed to fire a plug gap of .100", but that past .080" plug gap, plug wire condition became critical.  Olds used a .080" gap on some plugs in the middle 1980s, but a TSB changed that to .060" about two years later.  Seemed that on new cars, when the dealers would move the on the lot, the engines never got hot enough to keep the plugs cleaned, so they fouled AND warranty bought new plugs.  The change to .060" was the result.

 

This was all in an era were wide plug gaps were perceived to be needed to fire lean fuel mixtures for emissions purposes.  Which also meant "big caps".  As things have evolved, a "fine wire" .040" electrode and a .040" gap plug work pretty well.  A bigger "zap" plus better exposure to the air/fuel mixture result.  Not specifically the "zap", but the higher-quality "zap" from spark plug gap designs.  The original ACDelco RapidFire plugs had all of the tricks in them, but with a normal center electrode.  NGK V-Power plugs had the main upgrades and worked well. 

 

Toyota also used what was a V-Power NGK plug OEM, but with the normal NGK nomenclature/part number on it.  Which is how I discovered them.  Plus them touting the fact it would fire in leaner mixtures.  They worked better in my different cars, too.

 

Just my observations and experiences,

NTX5467

Edited April 28 by NTX5467 (see edit history)

[XframeFX]

On 4/26/2024 at 10:38 AM, RivNut said:

Has anyone heard anything about this unit?  HEI nailhead distributor from Speeday Motors.

Over the years, my project has had my research click on all the discussions above. Depending on what phase I'm at, I've thrown $$$ recklessly at an issue or solved it with a $10 part from Self Serve Auto Wreckers.

 

The Speedway product appears to be from "Top Speed Performance" for a fantastic price! No mention if the advance is curved for the Nailhead.

DUI now appears to be "Perfomancedistributors.com". Several businesses combined into one? I believe T/A Performance sells them as well. The DUI product is curved for the Nailhead and would be my choice for a drop-in Unit.

https://performancedistributors.com/product/buick-nailhead-dui-distributor/?attribute_pa_color-choice=black

 

Centerville Auto has a great Tech page on this. I don't totally agree on HEI comments. Yes, it's ugly but if no clearance problems, why not? It is self contained, is curved for the Nailhead (DUI), has an aluminum body and will be supported for many years. However, the website only emphasizes on advance curves for the Nailhead. Good but, what about that inductive spark? The recommended turn-key distributors products are good. Lets hope there's continued parts support for the them.

https://www.nailheadbuick.com/ignition-and-distributors-1

 

It is always recommended to optimize your ignition before messing with Carburetion. If the only goal is breaker point elimination, why not go the extra step and upgrade to a better .7 ohm coil for larger Sparkplug gaps? Also, the swap will allow continuous 12V operation, not just during cranking (elimination of ballast resistor).

Note, not all conversions can fire the heavier coil and not all "1-Wire" conversions are the same. Also, as recommended by Centerville Auto, stay clear of conversions with flying magnets. Lobe Sensing is better.

 

I spent about $250 on my ignition. A Motorcraft TFI module from the wreckers for $10, a .7 ohm MSD Blaster coil for $80, 8mm Taylor Spiro-Core wires and Bosch Sparkplugs clearance priced from rockauto. The money I saved can be spent for a good 3-in-1 Dial-Back Timing light that I have yet to find a deal on. I borrowed a friend's unit to tweak the advance with a separate tachometer. My new timing light will have an integral tachometer to enter values over the speed range into an XLS to plot out on an X/Y graph.

So, still with the original Delco-Remy look and breaker points inside. But at .010" gap,  they will last forever with periodic dab of grease on the rubbing block. I only wish the body was aluminum to go with my aluminum intake manifold.

 

Does anyone know if the last of the Nailheads (1966) were produced with Aluminum Delco-Remy Distributor Bodies like other GM Divisions?

 

 

 

 

Edited April 29 by XframeFX (see edit history)

[telriv]

John,

 

No "Nalheads" I know or seen EVER had aluminum distributors from the factory.

They were ALL cast iron.

 

Tom T.

[NTX5467]

Back when everybody was thinking that .080" gaps were what was needed for optimum power, it was those orientations which fueled the large-cap HEI and similar Ford distributors.  Which also led to the discovery of such high voltage sparks resulting in ozone formation in the caps and related misfires.  Which then generated the "ventilated" caps with holes drilled in their sides.

 

Later, after some dyno runs, it was discovered that anything past .060" plug gaps did not produce more power, with .060" at the top and .045" being down a few horsepower.  I had no issues getting a stock coil to fire a .040" gap plug.  The plug gap spec on my '77 Camaro 305 was .045".

 

After I read an ole Petersen Publications book on Ignitions, I discovered the Champion "J-Gap" plug.  It was a full racing application plug, in the later 1960s.  I spent hours filing those ground electrodes down on the Champion J-14Y plugs for our '66 Chrysler.  Getting the gaps just right afterward.  On the dealership's ignition screen, it showed about 9kv firing traces for them all.

 

With the later NGK V-Power plugs, they also had the cut-back ground electrode with a V-cut in the center electrode to force the sparks to happen on the edge of the ground electrode, without shrouding.  The will fire a leaner mixture, from my experience.  With the later fine-wire electrode plugs (as their Iridiums are) produce a completely un-shrouded spark kernel, for a berrer POW from their ZAP.  If their use in a lawn mower engine is accurate, better fuel efficiency, too.

 

I later started to use a pair of diag cutters to snip the ground electrode and file it back flat.  MUCH quicker, but all I had in the earlier times was "time" on Sunday afternoon.  Later, I just started to give the ground electrodes an easy twist to uncover half of the center electrode on myu lawn mower spark plugs.  Seemed to work just as well.   LOTS of "adventures with spark plugs" in my prior decades!

 

Enjoy!

NTX5467 

[NTX5467]

In reading the ignition and distributor section of Centerville's website, I read the part on distributor curves and it struck me that the only real difference in a "Nailhead" curve is the lower total timing recommendation.  Apparently due to a more efficient combustion chamber, it seems, which results in a lower total advance amount needed for best power.  Not unlike a Chevrolet W-Motor 348 or 409.

 

So, use the limiter bushing to limit the crank degrees' advance to 20 degrees total.  The MAIN thing.  Then set the base timing to 10 degrees BTDC for a total of 30 degrees BTDC.  Maybe a few degrees more with some camshafts was also mentioned.  Timing all in at 2500rpm?  "Hot Rodders" used to recommendations used to be to have the centrifugal advance all in by 2000rpm for drag racing.  2500rpm seems like a good compromise, to me.  I respect these orientations.  Just need the MSD advance curve kit to make things happen.

 

Enjoy!

NTX5467

[60FlatTop]

12 hours ago, NTX5467 said:

I later started to use a pair of diag cutters to snip the ground electrode and file it back flat. 

Just made me think back to a SBC that I side gapped and indexed a set of plugs in. That would have been 1972. The car was a  black '58 Chevy station wagon, 283 with a WCFB on it, '68ish Camaro close ratio three speed on the floor, twin Cherry Bombs, and a peg leg 4:11 gear set.

 

I don't know how well the plug fitting worked out but one morning I was walking along the ditch on the edge of town when one of the guys came out of the garage on the corner carrying the rear half of my driveshaft and asked "Are you looking for this? We found it by the gate".

 

I was living with my parents at the time and the neighbor's son came out back in our shared driveway. I told him his mother thought the car was a hearse the first time she saw it. He said "The first time you started it I thought it was a cannon."

 

Good memories on that one.