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kopeck 11-05-2012 11:11:00 169.244.176.116 Report to Moderator	I want to thank you all for this info, it seems odd to me that there's so many variables here but you don't seem to hear it talked about much. So here's another wrinkle, lets say an A was rebuilt with 3 1/8" stepped head pistons. Would it be better to go with a distributor off a later offset (100-140) with less advance or go for something more stock with more advance? Or is the reason the retarded the timing on the newer models more a function of RPM then cubic inches? I have done this, I'm more curious then anything. As to why not just put an H4 on it? Well it has one, and I've got problems that seem like ignition. I have a BN with a distributor which was installed as an upgrade kit form IH back in the day (still have the manual). I just like the way the BN runs better (this is before the A had problems). I do a lot of mid throttle putting around, pulling carts and what have you, and the BN just plan run smoother. K [Reply]   [No Email]
pete 23 11-05-2012 18:34:59 74.32.238.2 Report to Moderator	Re: IH Battery Ignition (distrubtor) in reply to kopeck, 11-05-2012 11:11:00   Spark advance should always be tailored to the compression ratio of an engine and speed it runs. Normally you can do comparison to different models like you said , newer models, and come up with satisfactory performance. A 35 or 40 degree advance was for a very low comp engine and when you increase bore size that changes comp ratio as you are squeezing more air into same size comb chamber, then you put in dome pistons further increasing it. Not a one size fits all. IH actually made a special impulse coupler for the H4 magneto to accomadate fire crater pistons on the M and H. Put one in for a guy who would not go to battery ignitions, about 45-50 years ago. [Reply]  [No Email]
TractormanNC 11-05-2012 12:47:57 108.72.58.200 Report to Moderator	Re: IH Battery Ignition (distrubtor) in reply to kopeck, 11-05-2012 11:11:00   Hey Kopek, Something else I didn't see in the previous posts (may have overlooked it), but a mag goes to FULL advance as soon as the engine starts. 30, 35, 40 degrees advance on an engine at idle. Kinda makes one wonder how they would even run. You mentioned a rebuilt C113 with step head pistons. Well here is my take on it from my experience. Rebuilt a 47 SA, originally had flattop pistons and a mag 35 or 40 deg impulse coupling. Overhauled it with fire craters. Ran OK at full throttle but at idle and mid speeds always had a slight miss. Finally convinced Dad to spring for the IH dist conversion kit. Put it in with the proper advance plate (22 or 25 deg I think) for the fire craters (came with the IH OH kit) and it purred like a kitten. So if you have step head pistons and a gas head, get a dist with a 20, 22, or 25 deg advance plate and it should solve your problems. [Reply]  [No Email]