Re: Best Ignition for 4.3?
I currently have had the Jacobs Mileage Master Coil, MM and wire set on my 95 4.3L 4dr auto. Blazer 4 dr. First thing is that when the system does work it works fine. Can't promise you the mileage that they guarantee though. My city driving (Washington D.C. Metro Area) is 15 to 16. My highway is great around 21 but if you look at the sticker for the mileage that is what the vehicle is supposed to get anyway. I have the 3.73 ratio rear axle and run the 235/75 R15 tires but as you probably know those aren't really considered "big" tires anyway. Jacobs people do not know what they are doing. Or I should qualify it and say that if your lucky to get the 1 guy in the place that knows what he is doing then you will get the proper parts. One thins is for sure, the wires go bad about every 2 years. In fact I stopped using their wires and am currently running Excel 8.0mm high heat wires with no problems. I don't have information on the MSD ignition but my readings and gut feelings say that it is better. For example the Jacobs ignition tells you that when you run their complete system you need to gap your plugs to .20 over factory spec. that puts it at .65 for mine. Most mechanics won't do that because 1) the spark plug has to start bending backwards to get that far out 2) there is a fear that a gap that big would start hitting the spark plug with the cylinder head. In any case I have run it with plugs gapped at .45 and .55 ABSOLUTELY NO DIFFERNCE in performance or mileage EXCEPT at .45 the engine idles so smooth that you can't even tell that it is on.
In Jacobs defense it does light up quicker. Can't say that the MSD doesn't do that already. It would seem to me that MSD has their stuff together better than Jacobs.