Coil Selection...does it matter?

[Murphy]

My 86 SBC has the Thunderbolt Ignition system and trigger-wheel style distributor. Can I use any aftermarket high output coil with this? How important is it to replace the coil with the OEM equivalent? What are your opinions on coils and the benefits of Hi Output?

Thanks,

Murph

[Formula Jr]

I don't think it makes any difference at all. The only difference between a marine coil and an auto coil appears to be the price . Hi-voltage coils are good if you're drag racing, but on a mildly tuned sbc or any marine v8 for that matter, there isn't any benefit I can see in the expensive stuff. A V8 coil is a V8 coil, is a V8 coil........

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The best way to get someone to think out of the box, is to raise them in a sphere--------- O. Saffell

[BUIZILLA]

Actually, there are SEVERAL automotive coils..

with or without ballast resistor?

with or without transisitor ignition?

J

[MOP]

I do think that hot coils help a little, they do keep plugs cleaner and make it run a bit smoother. But to take it a step further MSD, Jacobs and the like do make a real difference. I have used Jacobs it made my 4x4 start like it had injection in real cold weather, before the change it needed either at times also my mileage went up enough to make me smile. My engine idled about 100rpm higher when first started, that proved to me it was doing a good job. I must admit to having the Jacobs on the shelf and still run the stock Ford BID in my Donzi.

[DUCATIF1]

Is trigger wheel distributor a GM HEI style set up? Is coil in cap or separate? There are a lot of fancy looking coils that are just that. Best bang for the buck would be a MSD 6 Series with their blaster coil for external set ups. You will have to open gaps on plugs but you will have noticable difference. For coils in cap it is usually cheaper to buy entire new dist. set up for your specific application with higher output coil and HEI module built in. They will curve to your needs. They run about $250 and you can adapt older style to this with a one wire hook up. By the way I think I saw marine boxes in MSD'S catalog. Brian

[BigGrizzly]

HEI is totally different than Thunder bolt and not interchangable. I run a different setup in each of my boats. The Criterion has a Complete MSD set up drom distributor to coil and box. The Corsican has A Mallory Unilite distributor and Promaster Coil. The 1966 H&M 16 has a mallory dual point distributor and an old Ford coil with a ballest resistor. None have ever given me a problem at any time. Most problems are wires cap, rotor ot plugs. When I was a kid I worked testing coil and other ignition components for Delco We tested 1100 warranteed coils and found only three bad ones So I figure the techs just were parts replacers- you know -If I can't find the problem just replace everthing! Wrong way, but I see it every day.

[MOP]

Griz we call it "Easter Egging" There are a ton of guys that can't get it through their heads to start from one end to the other and completly check all related pieces. It don't take much longer and often you find something that may have been the initial cause or a weak part.

[DUCATIF1]

I am assuming your engine is in a good state of tune and you are looking for better performance?? A 4cyl coil and an 8cyl coil can be identical. There are varying outputs that are affected by dwell times and other factors. The MSD unit works great and is time tested unit. Jacob's is big bucks and their sales practices are questionable. Installing coil itself will probably yield zero results. The MSD box controls spark and length which promotes better combustion. Hey I am no scientist but when you can open the gap from .035 to approx .050 and produce a stronger spark you will have better combustion. You will not be disappointed with their products. By the way if you are not mech inclined buy all in one HEI style set up tuned to your set up. Cheaper,drop in , and you get new distributor out of deal for $250

[Murphy]

Interesting feedback. The reason I asked this question is I was just looking around the other night and came across this website http://www.vintageperformance.com/retrorockets/mercruis.htm

I noticed there are several coils listed and they're listed by distributor. Got me to thinking... why would that be? Does the coil need to be compatible with a specific distributor? If so, I never knew that.

Murph

Murph

[Murphy]

OK, I think I've answered my own question. Looked at the site again and the page is listing kits for upgrading points-style distributors. Was a little confusing. Turns out they only offer 2 coils. Here I thought I was on to something. Never mind, just a little winter stress syndrome

Murph

[knee deep]

Murph I tried to run a 260 hp Merc with a NAPA or something coil about 5 years ago. Didn't run worth a ****, bought the Merc coil which was three times the price but the boat ran so I guess it does make a difference. For that reason I think the old red monster is gonna get an MSD Blaster and........hmm............