What can you do to the ignition on an LT1 as far as MSD or something like that is concerned? Just want to make sure I get a nice, fat spark (or more than one of them!).

 

I dont think MSD has developed their own Opti unit yet, but you could add a Digital 6 box to give start and nitrous retard as well as a great high rpm spark.

 

Digital 6 the only option? I am picking up a Crane HI-6 for the 84 because I like the design and features and wondered if they had something for the LT1. I have used a MSD 6A back in the "old days" on my 87 T/A and never had a problem, just wondered if there was something better. Looks like the Digital 6 has just about all the stuff the Crane has. I will have to think about going that way on the LT1 in the 71.

 

Do not mate a multi spark box with your optispark - at best the opti will reward such a move with a shorter life. Given 10,000+ members on this forum I'm sure that there will be some who believe an add on ignition box benefited them, but probably none of them ever ran back to back dyno testing for any difference in power - I have, and no power could be found. What I did experience was a loss of reliability, and I can assure you that the number of people with problems from an add on ignition box on an LT1 outnumber those who think it was a good move.

Even in the situation of nitrous or boost retard, I have seen many ignition boxes that cannot/will not retard timing like they are supposed to. I have seen a number of retard boxes that would not retard properly, or had a delay in applying the retard, or would only pull back about half the timing they were supposed to - in short, they too were unreliable.

What to do? The '94 - '95 opti is a worthwhile upgrade for earlier LT1 engines. If your LT1 is a '95 or earlier you should install a low impedence coil, such as the one from MSD, (note that '96+ came factory with a low impedence coil). For sure a high quality set of plug wires should be used, I like the Taylor Spiro Pro 10.4 mm pre-made wireset (this will require different wire separator holders, also available from Taylor and others). For boosted or N2O applications I would strongly reccomend a custom flash (on '94+) via LT1Edit - furthermore I would reccomend not using an off the shelf PCM flash, get the LT1Edit software and do it properly with a 1/2 or full day dyno session. Not too many people want to admit that every car's tuning needs ARE different, because there are so few "exact duplicate" combos out there - you know, we say "well, its close".

Please, no flames, or replies from people who haven't ever used a dyno, or data logged a dragstrip pass. My reply is based on my experiences, and what I have seen first hand on other cars.

A good '94+ opti with a low impedence coil offers good spark up to ~ 7,000 rpm.

Thomas

 

I concur on the older style MSD 6 boxes shortening the life of the opti. I think the jury is still out on the digital 6 model but would not be surprised if it has the same results. I also agree on the coil advice. For plug wires the MSD 8.5's are very good also.