ignition questions
Thread Starter
Instructor
Joined: Jun 2003
Posts: 200
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From: Tempe AZ
ignition questions
Question 1) Whats the advantage of 8.5mm over 8mm plug wires on a relatively stock 1985 vette, if any?
Question 2) How many pins is the ignition module in my 85? I'm gonna get a new one as part of my redo-the-entire-ignition-system-project, but I wanna know what to order before I tear it apart.
Question 3) Does brand of ignition module/coil/wires really matter? And whats best? I ordered the fitted taylor wires from the mall, and I was gonna grab either accel or msd coil & module
Question 2) How many pins is the ignition module in my 85? I'm gonna get a new one as part of my redo-the-entire-ignition-system-project, but I wanna know what to order before I tear it apart.
Question 3) Does brand of ignition module/coil/wires really matter? And whats best? I ordered the fitted taylor wires from the mall, and I was gonna grab either accel or msd coil & module
Melting Slicks
Joined: Jul 2003
Posts: 3,229
Likes: 52
From: Pomfret, CT
Finalist 2020 C4 of the Year - Unmodified
Re: ignition questions (Corvettaholic)
I just put an MSD blaster coil and custom fit Taylor 8mm Spiro Pro wires on my LT1. Performance is up in the air right now. :sad: BUT..as far as fit goes....GREAT!! :) The Taylors were an exact match.
-Rick
-Rick
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: ignition questions (Corvettaholic)
Larger diameter plug wires provide more insulation and protection from the high voltage jumping through pinholes in the plug wire insulation and/or generating corona which reduces the energy of the spark at the plug.
There are 4 lugs on your spark control module. Due to the space and heat sinking capability of where the spark control module is located (inside the distributor), the amount of current the module can switch to the coil is limited and the coil energy is equal to 1/2 L I*2. L, the inductance of the coil primary is also limited due to the coil size and too much L starts to reduce the energy in the spark at higher rpm. The spark coil design is a compromise and GM has done an excellent job in the HEI used in their modern cars. I doubt very much that an aftermarket HEI ignition system can be felt to be any different than stock. If you want higher energy in your ignition, install a multi discharge capacitor discharge ignition!
There are 4 lugs on your spark control module. Due to the space and heat sinking capability of where the spark control module is located (inside the distributor), the amount of current the module can switch to the coil is limited and the coil energy is equal to 1/2 L I*2. L, the inductance of the coil primary is also limited due to the coil size and too much L starts to reduce the energy in the spark at higher rpm. The spark coil design is a compromise and GM has done an excellent job in the HEI used in their modern cars. I doubt very much that an aftermarket HEI ignition system can be felt to be any different than stock. If you want higher energy in your ignition, install a multi discharge capacitor discharge ignition!
Instructor
Joined: Aug 2003
Posts: 163
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From: Glendale Az
Re: ignition questions (Corvettaholic)
1) More insulation against crossfiring. Headers will still eat through them. 2) All computer HEIs use a 7 pin module, 2 for the coil, 2 for the pick up , and 3 for the computer (1 being ground). A hi po module will not increase spark, some claim that it sends a better signal to the coil. 3) I use strictly MSD on everything. Have had only one 6AL go out and I think the customer was screwing with it. (shorted it). Have fun. :chevy
