CDI Replacement

[Russ]

I recently developed what feels like a miss over 4900RPM. TD Automotive were kind enough to lend me a replacement CDI to test and it basically transformed the car (and gave me lots more power) my CDI had been making noises for a while and I was always a bit suspect of it.

 

So on this basis I'm going to replace my coil/leads/plugs/CDI and refresh the whole ignition side of the engine, as well as upgrade to Pertronix 'pointless' distributor and Magnecor leads

 

I've been looking at options and so far the M&W Pro 10 seems like the go (rather than a new CDI for $3250, or a rebuilt one for $600 - the M&W has current technology and is an Australian based company)

 

anyone got any feedback on these? I'll photograph it as I do the swap and report back when I'm finished

 

otherwise, anyone got any ideas on the miss? it's consistent at 4900RPM which makes me think it's electrical, my fuel filter has just been replaced and the mixtures/idle/timing set, as well as my fuel distributor was rebuilt last year (it only affects the engine at the revs mentioned and above, and it seems like a flat spot in a carburetted car) 

 

If it did it all the time idle as well as under load it'd be easy to diagnose!

[Harvs11]

 A little while back I had what was best described as a flat spot between 2000-2800.  Checked all the usual things like mixture/timing etc.

Tuning would disguise it but never quite fixed it.  The cuplrit was the frequency valve which controls the fuel pressure in the fuel head via a signal from the O2 sensor.  Once that was sorted the rest of the fuel system could be adjusted correctly and the performance improved across the rev. range.  It's worth checking. 

 

My car now runs without the O2 sensor which means slightly more fuel but more consistent perfomance and steady idle.

 

Thats about the extent of my knowledge on the black magic within the CIS system. 

[Uncle]

Do it and never worry about a DME again.

[Russ]

I don't think I have an O2 sensor (I think they're 80 onwards with an improvement to CIS) and I'm pretty sure I don't have a DME relay either (I think these start with the Motronic "Digital Motor Electronics" of Carrera 3.2's)

 

does anyone know a place I can buy all these items from too? At this stage i'll be buying the coil from the states, the leads from Sydney, the CDI box from Sydney all from separate locations (and plugs from Repco)

[Caledonian]

Cheap solution would be to only rev your car to 4899 RPM  

 

Possibly not the answer you were looking for though:( sorry

[Russ]

considering my torque converter bites at 2700, not really

[Russ]

so the plot thickens

 

for the price of the M&W Pro 10 in Australia, I can get a new MSD 6AL (with electronic rev limiter), Coil, Leads, Plugs from Pelican... The only negative I've seen about MSD was some competitor of there's on Pelican Forums

 

the other big plus is there is an install guide on how to do it in 101 projects

[Harvs11]

Mike from Spyder auto sells a different brand CDI replacement unit. I know there are a couple PFAers who have this conversion. Any reports?

[Russ]

I'll send mike a message and see what he has

 

did some further troubleshooting earlier by replacing my rotor button - I noticed a bit of play in the shaft (up and down not side to side) and this changed the affected RPM's so i'm guessing it's ignition somewhere, i'm hoping it's not in the distributor somewhere though

[Caledonian]

I'll send mike a message and see what he has

 

did some further troubleshooting earlier by replacing my rotor button - I noticed a bit of play in the shaft (up and down not side to side) and this changed the affected RPM's so i'm guessing its ignition somewhere, i'm hoping it's not in the distributor somewhere though

I saw a thread recently for distributer rebuilds on PP, appeared fairly straight forward (especially for a man of your talents) and inexpensive… might be worth investigating?

[Russ]

I did some more reading and up and down play in the shaft is okay, it's the side to side that is bad

 

I've still got my dust cover on there, I might just use that Bosch distributor grease and fit the Pertronix and see how it goes (unless there's some way of testing the magnets down the bottom)

 

I think my tacho is driven from the CDI so there's not much else to go wrong with it, aside from maybe a vacuum issue on the advance

 

 

I never like this stuff! would be nice if there was a CDI/Points/Coil/Lead/Plugs kit you could just buy off the shelf that's guaranteed to work together and deliver another 10hp-15hp

[Russ]

god damnit now I've found a perma-tune competitively priced. it will plug straight into the bosch 3 pin, and mount where the existing CDI is (but doesn't have multi spark or anything special)

 

so the options are:

MSD 6AL

Perma-Tune PR6501012

 

I'm not going to rebuild my CDI box and at $3250 new the cost is a bit prohibitive

 

I am going to fit new leads/plugs/coil/cap and a Pertronix Ignitor system though

 

so many choices!

[Russ]

So this morning before work I put together a cart on Pelican Parts with the MSD 6AL, Bosch Plugs, Magnecor Leads, MSD Coil, and Pertronix Ignitor II. I was just about to hit the button but then I remembered I had a loan CDI and should return it.....

 

So on the way to work I took the loan CDI back to T&D and went on with my day. After work I brought mine home and put it in the garage and went upstairs to my unit.

 

I ate dinner and watched Petrolicious and got 'the bug' to do some car work, so I went to the garage and reinstalled my CDI and made sure all the ignition leads were attached properly etc.

 

After finishing it up, took it for a drive and it's just as powerful as it was with the loan CDI god damn! It's running as well as it ever has (no rough idle, the miss it had at 4900 RPM is barely noticeable)

 

So back to the drawing board, I pulled some of my leads and they have corrosion on the end, and one of them has a missing resistor.

 

I think from here on I'm going to change my leads, change my plugs, change my cap and go to Pertronix Ignitor II. If that doesn't resolve my miss I'm going to go the MSD and coil

 

Now to work out what's the best upgrade path (so I don't need to do things twice if I end up with an MSD)

[911oclock]

How old are your ignition leads Russ? Try run the engine in complete darkness and look for any blue arcing, you can even spray a mist of water over the engine to help identify any issues.

[michel]

good news story - worth everyone checking the basics prior to pulling out the wallet - did a similar thing with my 99GT forester recently.

 

BTW a mate of mine, John   can rebuild CDI units.

[Russ]

How old are your ignition leads Russ? Try run the engine in complete darkness and look for any blue arcing, you can even spray a mist of water over the engine to help identify any issues.

 

I think they might be original so I'm going to replace them anyway, Thanks for the tip with the water, I did try in the dark and couldn't see anything (although I was probably gassing myself in the garage at the time lol)

 

good news story - worth everyone checking the basics prior to pulling out the wallet - did a similar thing with my 99GT forester recently.

 

BTW a mate of mine, John   can rebuild CDI units.

 

thanks, I might be in touch with him, any idea on a price for a rebuild? I've been quoted $600 locally

[michel]

Hi Russ

how did you go in the end? Just spent the weekend diagnosing fuel &  ignition issues with my Sporto. Better but no cigar get. 

Took a rebuilt  CDI unit I had on the shelf , it has improved things. Though am thinking about upgrades.

i believe there is a cpl of new options?  One unit called CDI classic plus? 

Anyone have some experience with CDI and or general ignition upgrades on their 74-77 cars. As much as I like points...

BTW John who has rebuilt mine has gone to ground. Though min charge was 350

[Russ]

In the end i changed a few intake seals, did the mixtures, got my fuel distributor rebuilt and then decided to just leave it with CIS. I think the MSD is the go for a reasonable CDI replacement (coupled with the coil) gives you changeable rev limiter with a chip change too.

eventually I'm going to put in a pertronix to rid myself of points.