[Goldenblack440]

I have a couple of new CDI units i want to try on my 360- has anyone used either of them ? Will there be much noticeable HP gains in normal driving? I have heard that the Summit Racing one is a rebadged Mallory (not sure though), and that the Mopar Performance unit is a rebadged MSD 6, which i am sure about. I think they will both do a similar job, both have adjustable rev limiters. But its reliability i am concerned about. MSD have not had a good history with reliablity and reading through the MSD forum i see there are just so many problems with reliability, erratic idle, misfiring etc

To their credit, both units have very comprehensive and clear instructions, MP even has some good general theory on CDI. Both have a lot of clips, plugs and wiring.

If anyone has used CDI on a SB, what plug gap did you find the best? I have heard that the gap can be increased to 55-60 thou ? (from standard 35-40)

thanks

[Eddie]

I would use the lower cost of the 2,,both are reputable. I have a complete MSD 6 plus billet dizzy on my smallblock and have never had a problem in the 6 years it's been on there. The only problem I ever had with MSD was inside the dizzy cap without any ventilation the inside will form green crusty muck,,I sent it back to MSD,,they instructed me to drill 2-- 3/32 holes on the side of the dizzy opposing each other, this allowed the inner cap to ventilate and stopped the 'green shit' from forming inside the cap. You can increase the gap to a much wider gap to allow more current to fire across it. The larger gap increases the resistance at the expense of the electrode and strap. I set my NGK's to .040 and have had them in there for 3 years with NO problems.

[dave-r]

I would set the gap to 45 thou. You can go as high as 60thou (not 60thou + 35) but I wouldn't go over 50thou as you will have problems getting the ground strap to line up with the center electrode correctly. That is perfectly flat and parallel with the top of the tip.

[Goldenblack440]

ok, thanks for info. hadn't thougt much about the gap and the effect on the groundstrap. until now.

[fbernard]

I confirm that the Summit is indeed a Mallory model. I've seen pics of both units in a Summit catalog last Sunday, and there's even a comparison of the most popular units. All electrical specs are identical.

I was looking at the catalog because my old MSD dizzy is so rusted inside I had full advance even when cranking. While this has really got bad lately, it seems I've had this going on for a very long time...

I almost thought about changing the ECU back to something simpler, like a FBO or a 4-pin HEI module, although I like having a rev limiter (I hate to check the advance with the MSD's multispark feature). I know on some Crane units you can deactivate the multispark for just that purpose.
Maybe that exists on other models as well. Sadly not MSD though.

[moparteenchalleneger]

i have the summit one in my truck it a really good ignition it is hookend up to a 360 as well

[Goldenblack440]

Thanks for the feedback Moparteen. What dizzy are you running with the Summit unit? Thanks for confirming the Summit and Mallory for me Bernard. What do you mean by checking timing and the multi spark? Does it make checking the static timing very difficult? At this stage i will be using a standard MP electronic dizzy. I have read that the multi spark cuts out after about 3000rpm (due to insufficient dwell time to create more than one spark) and after about these revs, one powerful spark is used. Can you notice the difference in the timing light reading when you rev the engine past this point?

[moparteenchalleneger]

i am using a stock one from checker i think