twin plug distributor - how unobtanium? / other options
 

OK - I am about to start building a new motor for my race/rally car. A few areas are dictated by historic racing rules but ignition systems are free.

I am having the heads drilled for twin plug whilst they are stripped - so as to leave the option open to do it in the future.

What is the best route - double "six plug" style dist off a C2? can you atually find the 12 plug single dist's anymore (I recall hearing somewhere that they were a Ferrari part)?

I would welcome any suggestions comments

Also, I'm looking at the new style MSD that allows rev-based timing changes - anyone used one??

FYI: The basis of the new donk is:
7R mag case
10.5:1 JE pistons
2.7 barrels
webers
S cams (can't go much wiilder as car also does duty as a tarmac rally car and you really need some low speed punch out of corners)

Aiming for 230-240 flywheel hp...into 960kg (2110 lb) car

Cheers - Ryan

ps. AUSSIES: my present 200hp 8.5:1 2.7 litre engine (early AL case) will shortly be for sale

I don't know that much about twin plug systems, but I do know, that if you are using a SC based motor & using a 964 distributor, you have to change the distributor drive gear.

Look into Electromotive ignition systems. They blow the socks off anything MSD makes.

Re: electromotive

the rules state "ignition systems are free. electronic engine management systems are not permitted"

I think I will have to get a ruling as to what they would class a MSD or Electro HPX - my thinking is they would be ok as the advance control is all they do

Well if ignition is free i suggest you to use custom ignition system (MSD, SDS, HPX etc.) with coilpacks.

It will probably cost less than very expensive dual dizzy and be mapable too.

Actually you could even install custom engine managment and just use ignition part and leave FI-pieces dangling :-) If rules change or you want more power: just add injectors, rails and other stuff.


Any way you go, waste-fire coilpacks are great and very dependable (no moving parts), and waste-fire ain't bad either in this application beacuse you connect each dual-coil to it's own cylinder so all energy will be used and none wasted.

It's cheap, reliable and programmable (for max power)...beats dual-dizzy in every department!

I have one of the old RSR-style 12 plug distributors, complete with cap and rotor. I may be interested in selling. PM me with offers if anyone is interested...

Thanks,
Matt

Ryan - you need to clarify what "ignition systems are free" means - it may be stretching the definition to have programmable ignition. I need to find out the same for my BMW.

If mappable ignition isn't allowed, I would argue the electromotive system is ok 'cause you only set an amount of timing, not really the shape of the curve, and it isn't really different to a mechanical advance in a dristributor.

If it is allowed, something which maps the ignition and has two coil packs would be good (as an aside, I reckon the VN Holden coil pack look just like the electromotive ones, and would be dirt cheap second hand).

Other options are (even more) $$$$ - RSR 12 plug or convert a 964 to work with yours (I guess this can be done on a 2.7).

The number of options is pretty wide - I reckon you need to clarify on whether the mapping is allowed (it has to be superior for driveability).

I think the caps for the RSR type are a coll grand. Someday even a good cap will get old and break.

You can convert the 3.6L twin dist.s by ripping out some of the guts and doing a transplant from an SC or similar (rotation direction issue).
I don't know that anyone has posted how to do this but it's the cheapest way. Steve Wiener may do it -- you want to look at hiw web site re power from bigger plug gaps also.

Steve Weiner did mine--'83 SC twin-plugged and 3.4-litered. It was no huge deal, as I remember, cost-wise.

Stephan

I paid several hundred for the 964 dist. and about $80 for the SC dist. BUT, the 964 item is usually close to $1,000. You have to get teh wire harness also. I don't think the labor is a lot.

I've got a big section that answers all of these questions in my Engine Rebuild book:

http://www.101projects.com

FYI, brand new 964 distributors are about $700 from us, I believe (or in that range).

-Wayne

Blatant book plug by Wayne! But it's one I agree with. Guys, I hope I never have to rebuild the engine on my old beater, and if I do, I'll want to remain a stock as possible. All that said, I think Wayne's book is a great read.

"electronic engine management systems are not permitted"


Under those rules, an arguement could be made against the original Porsche CD unit....I mean, isn't it electronic? Perhaps the rules should be clarified. Something like: Transistors & resistors OK, chips not.

Wayne - I enjoyed your engine rebuild book, maybe I should grab the 101 book as well (I was hoping to wait for the movie...)

HPX for twin plugs is about $1900

going the 964 dist route is expensive as well

dist................. $700
Dual msd's...... $450
dual coils........ $150
wires...............$350
tach adapter?..$85

total $1735

those prices are ballparks.. Im sure there is margin in either direction.


It would be a real stretch to call the HPX "engine management" all you do is set redline, and advance. You can hook up a MAP sensor, but with a NA engine its kind of useless.

The RSR twin plug dists are basically unobtanium, and the cap alone is about $1200...

Best bet is go for the HPX

Other opinions differ of course.

The 964 route however allows you to find desirable used pieces that won't break the bank.

I've seen used MSD units sold from auto parts stores on buy&sell boards for less than $100. I have seen good 964 distributors sell on e-bay for less than $300. What the heck, I've seen dual plug heads sell on there for less than $50 each.

You will probably not find hpx units on sale there however.


Good luck,
David Duffield

I'm going to be going with the HPX system that we sell. Retail is about $1400 or so for the two units, the pulley, sensors, and distributor plug. And, you never need to worry about buying a cap or rotor again. Much better than the 964 solution, in my opinion. MSD has a few options that are similar and cheper (slightly) than the HPX system, however, I don't know anyone who has used them, and you still need to get the crankfire pulley anyways...

-Wayne

I have the twin plug HPV-1 and love it. It hasnt skipped a beat in two years. It will unfoul a plug like you wouldnt believe.

Paul

The southern hemisphere cheapskate version I have been mentally kicking around...

1) convert existing dizzy to optical trigger (this is the bit I am struggling for info on, but I understand it is possible) - cost ~ NZ$300 (at a guess). Alternatively, use a crank angle sensor (more $$$ because of the expensive crank pulley)

2) run trigger signal to a Link IgnitionLink computer (NZ$1000 plus software, which isn't much either)

3) Link triggers 2x coil packs (NZ$150 each for the Holden one second hand - I have no idea if it would work - it is the equivalent to a Bosch BIC801. That engine is a Buick 3.8 by the way)

4) ignitors between Link and coils? $$$$?

5) Throttle Position sensor $$$?

6) Dyno time.

Would be cool, although I suspect the US$1200/NZ$2000 barrier gets seriously breached (the number in my head that I reckon it could be done for).

I want to do this sometime mostly just to see if I can. Kind of like installing EFi but the "lite" version (no fuel).

Paul - who makes the HPV-1? - Ryan

Cam - I like your thinking but can already picture the scrutineer starting to shake his head...