Twin Plugging - EFI or Mechanical

alphie · 07-20-2006, 05:47 AM

I am currently rebuilding my 3.0 SC (79) to a 3.2SS using mahle p&c (9.8:1) and dc20/21 cams.

I had my heads rebuilt by Henry including twin-plugging, race springs and TI retainers. Prior to removing the engine I was running TBitz megasquirt.

My question regards ignition. I'm undecided which route to take. To use megasquirt with Ford EDIS or go mechanical.

The pros for megasquirt are: lower cost?, enhanced control.

The cons are: less support (I've only seen a few example on this board of EDIS with megasquirt and only one person doing twin plugging), spark (will it be weaker as I've heard with other EFI twin plugging?)

The pros for mechanical are: tried and tested solution, strong spark, if I replace EFI with carbs I have a system that works.

The cons for mechanical are: less control, more cost, replacement parts are $$$?

Any help would be greatly appreciated?

smdubovsky · 07-20-2006, 10:21 AM

If you still have your case apart, then you can swap the distributor drive gear on the crank to that of the 3.2L and then plug in a stock 3.6L twin plug dizzy for ~$3-400. You'll need an EFI (which you already have) to trigger the CDI boxes but its simple, reliable, cheap(est), and easy to find parts for.

SMD

alphie · 07-20-2006, 10:34 AM

Hmmm. That seems like a great solution! From your signature, is this what you have done?

And yes, my case is still apart, I was about to button it up today but the main bearings I ordered were damaged!!!

alphie · 07-20-2006, 10:37 AM

However, where do you get a 3.6 dizzy for $400? Pelican has rebuilts for $750 that require a core?

smdubovsky · 07-20-2006, 11:10 AM

Yes, this is what I did. Actually, I started w/ one of the $$$ modified 3.6 dizzys modified w/ the SC trigger mechanism so it will run w/ carbs and no EFI (guys like steve weiner can do the conversion). I've since converted everyhting over to EFI and can trigger the CDIs directly from the ecu. I bought a normal 3.6 dizzy to replace the $$$ modified one but haven't gotten around to swapping it out yet. When I twin plug my SC powered carbed 914-6 and probably put that setup in it.

3.6 dizzys come up here and on ebay once in a while for that price. One of the dismantlers has one on ebay now for $500 (#8061941512) but you can do better w/ patience. Do yourself a favor and get one that has a good or recently replaced belt. I got a deal on one w/ a broken belt but its a PITA to change yourself. Someone advertizes on here a rebuild service - In retrospect I should have sent it out to them.

When you order the 3.2 crank gear, also buy one each of the different thickness shims. I forgot and had to reorder just a few $1 shims so the circlip will fit properly (+$$$ overnight shipping). They're cheap but will really hold up the reassembly

SMD

randywebb · 07-20-2006, 02:36 PM

"The pros for mechanical are: tried and tested solution, strong spark, if I replace EFI with carbs I have a system that works," and ability to increase plug gaps to 0.040" or so to get a tad more power. See Steve Weiner's Rennsport web site.

davidppp · 07-20-2006, 02:40 PM

MS'n edis twin..no contest at all.

The twin edis is totally bulletproof and gives an excellent spark.

I cannot imagine any reason to ditch MS apart from racing rules..

Kind regards
david

alphie · 07-20-2006, 03:50 PM

David, are you running that configuration?