Twin plug advice

[Bronco]

Thanks Henry.

that's really spelling it out for us.
Would you run the MSD (obviously much cheaper) instead of an Andial signal splitter? And is it all just bolt on and go?

Db

[Tom Sch]

hello,

i am going to use a marelli 12-plug distributor on my 3.2 SS.
instead of using two hkz, i am thinking about using two permatune with integrated rev limiter.

any experience with this configuration or any other ideas?

thanks

[Tom Sch]

hello,

if this tip should be for me - thank you! but theoretical i have two hkz witch i can use - but i don't want

i want to use something newer with a rev limiter...

thanks

[Cupcar]

The MSD model 6AL has a rev limiter built in.

I have used MSDs as Yoda recommends starting in 1989 on a Twin Plug engine. The rev limiter works very smoothly giving the engine almost the feel that the throttle blade is going over center and starting to close.

One thing though, stick with the Blaster 2 coils which have only a 140 milliampere current draw, some of the other MSD coils such as the Propower and HVCII draw as much as 2 Amperes!

The highest amp drawing coil that MSD recommends is their "Blaster SS" (in a single coil application) which draws 300 milliamperes; the Blaster 2 units work just fine since 2 X 140 ma = 280 within the 300 ma recommendation.

As an aside, I ran into an issue of misfire running a single plug engine on the dyno, it turned out that the problem was the output of a "Pro Power" series MSD coil fried the resistor in the Bosch rotor. Switching to a god old Blaster 2 coil eliminated the problem and the engine ran just fine.

[cay-ahe]

I'm going to give the JB racing twin plug distributor a try. It looks very similar to Henry's except it uses 2 MSD boxes. Not an expert, just a driver.

[Henry Schmidt]

Just to allay any confusion, the Supertec distributor can function with two MSD or any other pair of CDs. We offer the single CD system as a fail-safe system that shuts the engine down if a CD failure occurs. If you run two separate systems simultaneously and one fails, serious engine damage can occur. What is very common in our systems is to run two CDs one at a time separated by a switch. This allows for reliability of a twin system but less chance of engine damage.

[cgarr]

Don't you normally run less advance on a twin plugged engine?

[Tom Sch]

hello,

has really nobody any experiences with the Perma-Tune CD boxes?
Sometimes i have heard that they should fail often or doesn't produce good power?

thanks

[Steve@Rennsport]

Originally Posted by Tom Sch

hello,

has really nobody any experiences with the Perma-Tune CD boxes?
Sometimes i have heard that they should fail often or doesn't produce good power?

thanks

JMHO, but I won't install a Permatune on anything. I've been burned too many times since 1976 with failures on these things.

With Bosch CD boxes pretty much showing their age, I use MSD's and matching coils.

[lindy 911]

Keith,

Have you checked into a crank fire twin plug set-up? Clewett makes a complete kit that includes Electromotive parts and they say they are bullet proof. The whole set-up is around $1300 complete. I found a used 964 12 wire distributor on the Inet for $1500 but it's hard to say what kind of shape it's in. Then you have to add the MSD and by the time you're all said and done it's a lot more.

The Electromotive set up lets you adjust the timing in three stages, idle, 3,000 and 7,500. At 7,500 you can add or subtract (retard) timing.

Just a thought.

Lindy

[kenikh]

I have a blue one and it has never failed. The silver ones are apparently a disaster. I still keep a spare in the car.

[cay-ahe]

Originally Posted by lindy 911

Keith,

Have you checked into a crank fire twin plug set-up? Clewett makes a complete kit that includes Electromotive parts and they say they are bullet proof. The whole set-up is around $1300 complete. I found a used 964 12 wire distributor on the Inet for $1500 but it's hard to say what kind of shape it's in. Then you have to add the MSD and by the time you're all said and done it's a lot more.

The Electromotive set up lets you adjust the timing in three stages, idle, 3,000 and 7,500. At 7,500 you can add or subtract (retard) timing.

Just a thought.

Lindy

Yes, initially that was my plan.

The products at Henry's or JB racing have been getting good results and seem to have good reliability (roughly similar pricing). My opinion is based on and shaped by people that know a lot more about this than I do. I know reputable engine builders are using all these products. When I read the installation instruction for the JB racing setup it just looked very clean and straight forward. I hope it is ??? My .02

[Henry Schmidt]

I have used Permatunes on and off over the years and have had good results.
One thing we always do is by a coil that matches the unit.
Porsche coils have far too much impedance for the Permatune units.

[nocarrier]

Quick question.

When one of the CD's fail in a twin plug application where both CD's and both coils are running at the same time although separate; Is the risk of engine damage because the timing is set that much closer to the pistons TDC?

I am assuming that if one system fails; The timing is now way too advanced and due to the delay of flame propagation it causes detonation.

Can someone verify this please?

[Peterfrans]

Originally Posted by nocarrier

Quick question.

When one of the CD's fail in a twin plug application where both CD's and both coils are running at the same time although separate; Is the risk of engine damage because the timing is set that much closer to the pistons TDC?

I am assuming that if one system fails; The timing is now way too advanced and due to the delay of flame propagation it causes detonation.

Can someone verify this please?

Yes, just as for the 964 twin distributors where the toothed belt snapped you are effectively running single plug

[psalt]

the risk of engine damage because the timing is set that much closer to the pistons TDC?
I am assuming that if one system fails; The timing is now way too advanced and due to the delay of flame propagation it causes detonation


No, the total timing with twin plugs is less than single plug. The timing would be retarded, not "way too advanced", for single plug ignition.

[MBruns]

Kieth, I would be glad to discuss the 12 pin dist. we build, If you like give myself or Jim Higgs a call, we also are building a 6 pin dist. with the same internal components for 2.4 and up that will trigger MSD, we plan to do one for the 2.0/2.2 as well and also the 3.2 and SC.
Thanks for your interest, Mike Bruns JBRacing.com

[eapcpa]

Keith,

You should call Mike Bruns and discuss your application. I am using his product and it was very easy to setup. I have two coils and two MSD boxes but I run the coils on one box at a time. I have a switch in the engine bay to switch boxes and related pickup coils from the distributor. I plan to move it to the drivers compartment when I figure out where I want it so I can switch on the fly. I also have a kill switch for theft protection that essentially grounds the CD box so the car won't start. You can see the two sets of pickup wires in the pic.

[cay-ahe]

Originally Posted by eapcpa

Keith,

You should call Mike Bruns and discuss your application. I am using his product and it was very easy to setup. I have two coils and two MSD boxes but I run the coils on one box at a time. I have a switch in the engine bay to switch boxes and related pickup coils from the distributor. I plan to move it to the drivers compartment when I figure out where I want it so I can switch on the fly. I also have a kill switch for theft protection that essentially grounds the CD box so the car won't start. You can see the two sets of pickup wires in the pic.

Ed,

That looks great, exactly what I hope to do as well. I'd like to do a cockpit switch as well. Thanks for the input.

[Peterfrans]

These 12 plug distributors do look very nice, but I am still thinking about the potential cost saving with the clewett setup. What would be the drawbacks, if any for using a crankfire ignition on a MFI engine?