Very Cool Ignition Upgrade

[Zed Head]

Destroyed distributor cap buttons does seem to be a problem with the GM HEI distributors but conductivity differences between "carbon" and "bronze" materials seems unlikely as the cause.  Arcing and/or bouncing due to a weak spring and poor contact seem plausible since that would produce heat.  But straight-up heating of the button from high current and resistance-heating, without overheating the coil or ignition module doesn't really fit.

 

Just saying, check the other parts too: the spring strength and the contact point, and maybe put a dab of conductive grease on the point.  They're probably more important than the button material used.

 

Edit - forgot about the other half of the contact.  The rotor (also sometimes called a "button") contact.  It needs to be smooth and conductive also.  That tiny little area is usually overlooked.

Edited September 22, 2015 by Zed Head

[zKars]

Mopac usually stocks them as well. Do you still have a Mopac in Calgary?

You betcha. On the way over this afternoon. Thanks

[Chickenman]

Melting of GM distributor caps ( and others ) is well documented in many High Performance Ignition books and I've personally seen lots of melted GM caps ( around the center button ) from high heat when high current coils are used and the stock High Resistance button is not changed.. Not just my own stuff, but many Autocrossers working with the HEI dizzy's.

 

I use Standard Blue Streak "  X " series caps ( Premium line ) which are top of the line. Better than MSD quality wise and even those will melt because of the high resistance stock GM buttons. Nothing to do with poor rotor contact as we are dealing with new High quality race parts..... although poor contact or corrosion certainly doesn't help.

 

And yes you can fry the coil or modules in addition to melting the cap if you get unlucky. Arcing creates a huge amount of EMF that internal dizzy modules don't like. And the coils will get danged hot as well. Internal coils are the worst for heat failure. That's why I always converted all of my HEI systems to external coil and external Ignition box. The large dizzy cap was about the only thing really good about the HEI dizzy's in race applications. 

 

MSD " Cap Adapt " with the large diameter Ford type caps was a good choice as well. The larger diameter really helps to dissipate ionized gases in addition to other benefits.

 

Quality of the center Carbon brush on aftermarket Dizzy caps also varies greatly. Some of the aftermarket parts ( all makes of cars )  are a very soft carbon and just seem to disintegrate when too much current is passed thru them. The stock GM brush and the Standard Blue Streak X series seems to be pretty hard and durable, which is why it melts the cap instead of the brush disintegrating.

Edited September 22, 2015 by Chickenman

[Chickenman]

You betcha. On the way over this afternoon. Thanks

Hey Jim. Might be interesting to measure the resistance on the Bosch carbon button and the MSD one. Off to check my 280ZX dizzy button now.

 

Edit: Beck Arnley 280ZX Turbo center button reads 3 ohms, so that is a low resistance button obviously. Hard to gauge how hard or soft the material is though. The MSD buttons, being made of a bronze material stand up very well.

Edited September 22, 2015 by Chickenman

[Zed Head]

An actual resistance number would be informative.  You can't tell much by color.  The other half of a "melting" problem would be heat dissipation.  Heat is produced in all electrical components.  My point is to look at the complete system.  It's not just the material used, and as you pointed out, materials and their qualities can vary.  All we really know about these "buttons" is that one looks like "carbon" and one is yellowish in color.  long with that is the fact that many aftermarket perfromance parts are sold on old reputation and are, in effect, just brand names now.  Quality has been lowered to maximize profits.  

 

Could be that 123 chose an inexpensive supplier.  The original failure described was with the 3 ohm system.  Definitely not high energy.  Current flow should have been relatively low.  The replacement parts might have damaged the 123 module, but the cap was already damaged.

 

I'm using the stock GM HEI module with the stock GM HEI coil on the stock Nissan 280Z distributor and cap.  20,000 + miles, no problems.  No need for an aftermarket coil, the stock GM system is plenty.

 

I like to dig in to the real numbers behind these issues.  It's just fun to do.

 

 

Edit - overlapping posts.  I see we're all headed the same direction...

Edited September 22, 2015 by Zed Head

[zKars]

Well I got the MSD 8214 center contact. $15 canuck bucks. Nice piece, but about 2x larger diameter than the mini center in the Bosch cap.

Its not clear, but it appears to be not solid, so its not going to be practical to machine it down to size. Pretty tiny, my lathe is not....

So now its a balance of how much $$ and time to design/make verses buying a few stock caps. The one we found in Port Alberni came with a $50 price tag. Ouch. Rockauto are $25ish, but with shipping for me...

[zKars]

Measured the resistance end to end of the MSD button. ~2 ohms. Not that different from the carbon tip in the new Bosch cap, which is ~5 ohm. I think the difference is heat tolerance more than conductivity.

[Zed Head]

It's fun to make things better.  But the 123 ignition system has been around in the 3 ohm primary circuit form for many years and probably many miles.  Seems like a design problem would have shown up in that time.  Maybe you just got a bad cap.

[Chickenman]

(Snip)

So now its a balance of how much $$ and time to design/make verses buying a few stock caps. The one we found in Port Alberni came with a $50 price tag. Ouch. Rockauto are $25ish, but with shipping for me...

Jim, I looked up the Bosch 03014 cap at Rock Auto and it comes up with a 1968 Porsche 911 listing. OEM Bosch cap is only $19.68 CDN. You could ask Rock Auto if they will ship via United States Postal Service. USPS does not charge the outrageous " Brokerage " Fee's that FedEx, UPS, Purolator etc charge for cross border shipping.

 

I live close enough to the Border that I just keep a USA address at Mail Boxes International. Comes in very handy for shipping. Saves a lot of freight and " handling " charges.

[Chickenman]

Measured the resistance end to end of the MSD button. ~2 ohms. Not that different from the carbon tip in the new Bosch cap, which is ~5 ohm. I think the difference is heat tolerance more than conductivity.

I think you could be right...

 

Rod Lovett had the exact same problem on his Supercharged 260Z with an aftermarket dizzy cap. Disintegrated the dizzy center button. Brand new Aftermarket parts. Quality of parts is so hit and miss these days....

 

He's trying a Genuine Nissan cap now ( still available ) to see if that cures his problem. MSD 6AL ignition with MSD Blaster 2 coil.

[jmhtx]

For those of you with a 123ignition Tune model, can you clarify what you did with blue wire?  I understand the red and black and that they yellow is for a switch to change between advance tunes while driving.  The instructions are not clear on what the purpose of the blue wire is and the only reference i found was in the diagram at the end of the manual.  

 

 

[Mike W]

Blue is ground if I am not mistaken.  The blue and red are reversed in a positive ground setup so I do believe that is what it is for.  I can check my actual install later today and confirm for you.

Mike.