IH tool bar planter

Some planters have a shaft driving all the row units - that shaft will have a set of sprockets & chain & be driven off of a bigger planter wheel axle, you need to change that combination of those sprockets to get a different seeding rate.

--->Paul

Change the drive sprokets to change the throw.

Allan

There are several plates that plant "flats", because of the many different sizes of flats.
Can you tell us what the plate number is? If it's a plastic plate, what color is it? Also, do you have your planter set up for 16 cell or 24 cell plates (owners manual would tell you the sprocket settings for each.)? If you have planter set up for 16, for example, and you put in a 24 cell plate you will have a train wreck.....and same for other way around.
Sweet corn can be hard to plant because so much of it is usually "wrinkled like a grape".

Have you looked at the corn hopper floor plate? Does it have grooves around outer edge because of wear thru the years? Check this out thoroughly and get back to me. I'd love to help you with this if I can, but need more info.

As I recall one could also change the drive sprockets to slow that unit down.

Most of those planter plates I've seen are 16, 20 and 24 cell, thus with 16 you've gone as far as you can that route trying to space seeds out. Regardless of which way your seed units are driven there should be a chain sprocket reduction. Do you have any photos, there is someone on here that will recognize what you have. Once you do that then get a proper manual, and it will tell you what was available way back when. I'm not familiar with all plate type planters, however all the ones I've been around had the ability to space seed 12" or more apart.

If you don't have photos, go to the implement photo gallery here at YT, just type in planters, you might just find something identical to your own. I guarentte the resources on here will nail it for you. These guys never fail, sometimes it takes a bit of chewing, but we will prevail..