Greg Bender
http://www.thisoldtractor.com/gtbender
Here is the biggest you can go and still use the stock hold down bracket (and fit the side covers):
I used to be a proponent of the very inexpensive lawn and garden tractor batteries such as the Interstate SP30R Battery with 290 CA and 230 CCA or the EverStart U1P-7 garden tractor sized battery with 350 CA and 275 CCA available from Wal-Mart. However, these batteries have low cranking power and vent corrosive gases. I was never completely satisfied with them. But, if you are on a budget, these will definitely get the job done inexpensively.
A great battery choice recommended by John Ulrich is the Odyssey PC 925 MJT with 380 cold cranking amps and 925 cranking amps for 5 seconds. Since it is completely sealed, it is installed on it's side and fits well in the battery tray. Battery Mart.
George Dockray was kind enough to send me a couple of photos of his PC 925 installation. He glued rubber sheet to a piece of 3/4" plywood for the base to get it out of the way of the bolt heads and base tabs.
Greg Field reports that the Odyssey PC 545 and Odyssey PC 680 batteries fit and function well.
Charlie Mullendore has informed me that the AC Delco 51R-60 battery fits. Here are the details:
The Group 55 battery size is pretty much discontinued by everyone. If you do find one, it may be very old. My recommendation is that you do not waste your time trying to find one of these. However, I've kept the information on them below for reference.
However, based on recommendations from Robert A. Greene and Mark Etheridge of Moto Guzzi Classics, I have now chosen to use an AC Delco Group 55-6 year battery with 535 CCA. I picked one up from my local auto parts distributor. A Napa Group 55 battery may also work, but doesn't fit as well as the AC Delco.
If your local auto parts house just has to have a vehicle to look up a part, try any of the following:
- 1993 - 1995 Kia Sephia
- 1987 - 1990 Jeep Wrangler
- 1978 - 1980 Ford Thunderbird
As for installation, I was able to use the stock battery hold-down bracket and the long L-shaped bolts. I did have to modify the battery a bit, though, in several places. Along the bottom of the battery there is an extra chunk of plastic that is usually used to clamp the battery to the battery tray in cars, etc. This extra chunk got in the way of the four tabs on the battery tray. Some quick work at the bench grinder got rid of those (I just love grinding on a battery with power tools!). Also, on either long side of the top of the battery, I whittled away some extra plastic so that the hold-down bracket would fit snug. I just used a razor blade for this work. Since this is a top post battery, I found some adapters at the local parts store that worked well for mounting my ring connectors.
I am very happy with this battery. The starter cranks much faster and the lights are less susceptible to dimming with engine speed. This upgrade was well worth the extra money and minor modifications.
Follow-up: My AC Delco battery worked very well for nearly 2 years...then died. The battery was already old when I purchased it and no replacements were available. For now, I stuck my old garden tractor battery back in.