MGB: Battery size

This question is for all who have converted the two 6 volt batteries to a single 12 volt battery. I took the battery out of my 76 B and it won't fit the battery box it is too big. This is for the 70 GT. Even with the plastic battery box removed it is still too big. And I thought the B battery was small. Is there a special battery I need, or do I just take the measurements and try to find one that fits. I have all the main Auto part stores close by so whatever store you got yours at I should be OK with that.
Thanks Ken

Hi Ken,

Go here and download the instructions: http://clarkandclarkinc.com/1001_batbin.htm

You will see your answer for fitting a small 12V.

Cheers,

Robert

You want to find a group 26 sized battery. They have the correct basic dimensions. The variable to get it to fit is that it not have too wide a flange at the bottom for bottom clamped mounting. (Or you can shave/sand the flanges off)
The group 26 I was using (prior to the Westco I have now) came from Napa. (and the one before that came from Walmart but it failed within 6 months...)

A Miata battery fits perfectly and is maintaince free. RAY

Group size is only a general measurement. Different manufacturers will have different thickness cases and this will affect how the thing fits. The hole is tapered somewhat. Measure the bottom. And seek out a unit a taste smaller than that. You can use a plain old saw to cut off any clamp-down ears olong the bottom as long as you make sure you don't cut into the case.

Thanks for all the quick reply's....You guys are the greatest!!!
Thanks Again
Ken

Most of us run Group 26 (but you may have to cut the mounting ears off - I did). But Ray is right - the Miata battery is small and a great fit. The original style Miata battery is a gell cell - no worries about leaks. NAPA has Miata style batteries but they are more expensive than a Group 26. They do have a vent you can attach to a hose and lead any fumes away from your battery box.

This (attempted) Chart is info taken from two different Battery industry sources. As you can see, there is more than just one possible battery. The last listing in Italics is the size of the OE 6V batteries which gives some notion as to what the boxes were designed for.

Possible substitute batteries for the MGB

All are top terminal types


L 8 3/16 - W 6 13/16 - H 7 3/4 - Group 26 - Amps 525

L 9 1/16 - W 7 1/16 - H 7 11/16 - Group 75U - Amps 550

L 9 1/16 - W 6 13/16 - H 8 - Group 86 - Amps 525

{L 9 1/8 - W 7 1/8 - H 9 3/8 - Group 1 (6V) }

Usually there's a group 24 battery specified for a RBB. That's probably why you can't transfer it from your 76 to the 71.

I used a group 26 batt from Interstate Batteries. They make a model called a megatron+ that has a very high reserve cca and are rated at 0 degrees. It fit my 72 B roadster without any mods and spins the motor like an air grinder on steroids.

[quote="RAY 67 TOURER"]
A Miata battery fits perfectly and is maintaince free. RAY[/quote]

LOL......

That would be sacrilegious.