Electronic Ign. for a 750 Twin

I have a 77 750 with the points right now. I know that it has been gone over before, but I forgot what was said, and the search didn't turn up anything. Anyways:

If I want electronic ignition for the twin, can I use the pieces from the later "ltd" models? What years?

Did the 400/440 ever come w/ elec. ign? Would it work?

Any other models?


Thanks

pistolpete wrote:

I have a 77 750 with the points right now. I know that it has been gone over before, but I forgot what was said, and the search didn't turn up anything. Anyways:

If I want electronic ignition for the twin, can I use the pieces from the later "ltd" models? What years?

Did the 400/440 ever come w/ elec. ign? Would it work?

Any other models?

Thanks

Sorry I don't know the answer to your questions specifically, but I just want to mention in case you don't already know that Newtronic makes an aftermarket electronic ignition for the 750 twin. I have one.

I went to the archive and did a search "440 750 ignition" and came up with a bunch ! This is just one thread.

kzrider.com/forum/viewthread.php?tid=24226

82 and 83 750 twins had electronic ignition, but I have never seen those parts on eBay (in the last two years anyway), I think 81 or 82 440's and newer had electronic ignition and the parts can be had on eBay for less than $50, and it only takes about a half hour to install.

Or if you are really cheap (like me) all you need is the 440 timing advancer, and Lou (loudhvx) has a design posted on his website for an igniter that can be made for $5 or less.

I don't about $5. I'm cheap, but not that cheap. Maybe $15.


This is for a 4 cylinder,but you only need 1 HEI module for a twin.
www.geocities.com/loudgpz/GPZgmHEImod.html

Someday I'll work out a way to use the points as the trigger.

Post edited by: loudhvx, at: 2006/02/24 01:59

I got the HEI moduel from a junkyard for free, told you I was cheap :laugh: :laugh:

Free!? Alright!

Ok, a few more questions:

Primary resistance must be larger than 2.4 ohms, so do I have to get a coil from summit racing that is made for hei, or can I just get a normal coil meant for cars w/ points? (I do not know their given resistance, I just assume that HEI coils must be different given their 2x price) OR should I just use motorcycle coils. I saw a write up here using gm coils from a quad 4 (they have 2 outputs I believe, and that was supposed to be a large improvement)

Do I have to get resistance wires/plugs?

thanks

P.S. While we are talking about this, I would assume that the HEI route has a huge performance (not to mention parts avaliability) over stock 440 ignitor, or even aftermarket systems. The HEI coil is meant to fire 8 times a revolution up to about 6,500 rpm (stock modules), so a twin at 9,000 would not even make it sweat. Am i correct thinking this?

Post edited by: pistolpete, at: 2006/03/03 17:45

HEI coils (GM brand) are specific to GM, that may be the reason for a higher price. Stock coils should work fine, I don't think any of the KZ coils have less than 2.4 ohms resistance.

I don't think there is any performance difference, but have you priced a stock 440 ignitor? I think you can get aftermarket versions for ~$100 :woohoo:

Stock, Accel, Dyna, take your pick, they will all work fine. The HEI module simply acts as a trigger to fire the coils, and in this case is just a cheap replacement for a 440 ignitor (or is it igniter?), or you could keep an eye on eBay and/or check out local junkyards to get a stock 440 ignitor.

Pete, Steell answered it.

As you said, car coils (for distributor cars) are meant to fire more often than our bike coils. They would theoretically work, but they are much bigger and would get a lot hotter in our application. They are also usually much lower in resistance than our bike coils. This would really stress out the HEI module. You want to use coils in the 2.4 to 4 ohm range. Preferrably, 3-ohm so you can use a Dyna ignition if you want to later.

The Accels and Dynas come in 3-ohm varieties. That's what you want, or stock if you know for sure they are good and are not cracked at all anywhere.

Oh and to answer your question, it's not the RPM that stresses out the HEI. It is the total average current. Less ohms means more current which means more heat in the HEI (and the coil). Duty-cycle affects average current. Thye stock electronic ignition uses about a 30% duty cycle (30% on, 70% off) which is determined by the pickups and the rotor.

Post edited by: loudhvx, at: 2006/03/03 21:39

Post edited by: loudhvx, at: 2006/03/03 21:40

Thanks